Machininggraphitewith coolant

I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

3. Dust evacuation. The dust created when milling EDM graphite electrodes also is very abrasive. This abrasion quickly degrades the milling cutter, but it also presents a hazard to the machine and manufacturing environment.

One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

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Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Milling graphitefor sale

Graphite is strong, but brittle, and its abrasiveness makes machining without undue tool wear a challenge. Photo courtesy of Makino.

“In reality, graphite is much easier to machine in terms of spindle load when compared to machining steels,” explained Brian Pfluger, EDM product line manager for machine tool builder Makino. “EDM-grade graphite is much softer than steel, allowing for higher machining feed rates, but the material turns into a powder or dust when machined.”

Machininggraphitefeeds and speeds

“Most graphite is now machined with either carbide- or diamond-coated tools,” said Bond. “Both of these types of materials hold up well to the abrasiveness of the carbide.”

Because these design features are common across most machines regardless of builder, the decision on what machine to buy often comes down to the tolerances that need to be held.

Forum Responses (Solid Wood Machining Forum) From contributor M: In a nutshell, carbide is a lot harder and as a result, more brittle. That final hone crumbles the edge, whereas HSS burrs rather than crumbles, ultimately leaving a sharper edge. However, as you noted, the life of carbide is far superior to HSS steel, so your slightly duller tool is going to be slightly duller for a long time. The comparison of carbide to HSS is more common in moulder and planer work than CNC applications. Stick with your carbide inserts on the CNC. From contributor R: Well, there are some materials that you just don't want to use steel on, like MDF or plywood. They will dull steel fairly quickly. Carbide tips and inserts are composed of very fine particles that are compressed or sintered into a whole, so the finest edge or corner that can be achieved is relative to the particle size. Steel particles or grains are more homogenous, and can be shaped or polished to a finer edge. All this is on a microscopic level, so it really doesn't apply much to the person doing standard wood machining and molding, except that the carbide tooling will last much longer before getting dull. If you are doing carving or fine joinery, the polished, clean cut of steel tools is more obvious and you are not as concerned about tool edge life, because you are continually touching up the edge. I use carbide tools and inserts almost exclusively on CNC equipment, and steel tools for handwork. From contributor A: The technical answers to your questions above are right on the money. For a real demonstration, you need to use a HSS bit in a hand router. I used to make my own custom bits. The blanks are just big steel paddles. The first time I went to use one, I was a bit terrified. No anti-kickback body, just a big wing. That first cut was an eye opener! The router swept into the cut just as smooth and easy as you please. A carbide bit of similar proportion cannot compare. Carbide will certainly last longer under most conditions, but I believe we have lost much by abandoning HSS. HSS is also vastly preferable to carbide in high heat situations. For deep mortising cuts, a HSS bit will outlast a carbide every time. Excessive heat breaks down the bonding agent that holds the carbide particles together, causing the particles at the cutting edge (thinnest part) to fly off, blunting the edge. From contributor J: Carbide starts out dull compared to HSS, but just stays that way for a long time. And I'm learning (again) with the moulder that it's best for the harder woods. We profile sand everything anyway, but with ash, walnut, mahogany, etc. it does not do as good of a milling job. But you get into the hard maple and you can run for weeks without resharpening. Carbide is a godsend if you have an application that can benefit from it. From contributor B: The non-scientific explanation... Steel can be made very, very sharp because it is steel (metal/iron). It has a long-grain molecular structure that lends itself to the production of a long, sharp edge. Carbide (carbon) on the other hand, is not a metal at all, but only very hard little rocks. These individual rocks (atoms) are crystalline in structure and do not lend themselves to any kind of a long sharp edge. They're just very, very hard. Diamond, for example, is the hardest of all and is pure carbon. When alchemists and wizards eventually learned to mix the two together, they came up with an iron that is as hard as rock, but unfortunately not as sharp as steel. Why is that? The little carbon atoms are suspended within the greater iron matrix, making it very hard, but it's still the edge of steel that does the cutting. It's a compromise. They traded some of the inherent sharpen-ability of iron for the hardness of rock. HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

In the North American market, graphite typically is the standard electrode material for most electrical discharge machine (EDM) applications. These electrodes enable faster roughing cycle times and cost less than copper electrodes.

Jan 21, 2021 — Use a compression bit for both cuts. 1/4" works, but 3/8" is my favourite. When cutting the 3/4" holes, use an inside profile cut with a spiral and an offset ...

As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

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1/2″ Turn & Boring Tool Right Hand. Price$37.00 · 1/2″ Turn & Boring Tool Left Hand. Price$35.00 · 5/8″ Turning & Boring Tool RH. Price$40.00 · 5/8″ Turning & ...

A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

- Dust containment and collection components. It is critical to manage and collect the graphite dust produced during milling. All graphite mills are fully enclosed, and many machines offer large-capacity dust collection and filtration systems to evacuate and collect the graphite dust.

HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Graphite millingmachine

When alchemists and wizards eventually learned to mix the two together, they came up with an iron that is as hard as rock, but unfortunately not as sharp as steel. Why is that? The little carbon atoms are suspended within the greater iron matrix, making it very hard, but it's still the edge of steel that does the cutting. It's a compromise. They traded some of the inherent sharpen-ability of iron for the hardness of rock. HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

“The typical minimum RPM for a graphite mill should be 20,000, but 30,000- and 40,000-RPM spindles are growing in popularity,” said Pfluger.

Pfluger agreed that management of work flow is a factor for any shop, even with automation, and that the EDM should ideally perform its tasks relatively unattended.

Milling graphitecnc machine

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“The mix of small and deep electrode geometry requirements need smaller cutting tools, which pose a challenge to milling spindle RPM,” said Pfluger.

Graphite has specific properties that make machining a challenge. It’s strong, but also brittle, and is susceptible to chipping if not handled properly.

Some graphite milling machines can even perform both graphite and steel machining for added flexibility and can be changed over relatively quickly. However, graphite machining is performed dry, whereas steel machining typically is performed using coolant.

- Special covers and seals. Most graphite milling machines are designed with additional seals and special covers to prevent the graphite dust from escaping from the work zone.

Depending on job requirements, it is best to have all electrodes machined prior to starting the EDM operation. This will allow an EDM operator to set up, locate, and program all of the electrodes in the machine’s automatic tool changer (ATC) for all the needed part features at one time, and will help to maximize unattended machine operation.

It can be used to mix ceramic powders, disperse particles in solvents, homogenize ceramic slurries, etc. Ball mills operate by rotating plastic jars around a ...

“From a health and safety standards perspective, companies should refer to the information provided by graphite manufacturers for the proper way to handle and dispose of graphite waste,” added Bond.

“It is even possible to automate a sinker EDM and graphite mill together, allowing for the simultaneous processing of parts and electrodes without the need for operator intervention,” said Pfluger.

Milling graphitemachine for sale

“Albeit slower than milling or turning, newer EDM power supplies can machine graphite with very complicated details, tight inside corners, and with extremely fine finishes and straightness,” said Bond.

Before being loaded into the ATC, each electrode needs to be inspected to identify any flaws, chips, or incorrect features. This typically still is a manual operation performed on a CMM or digital optical comparator that measures the profile form and, in some cases, checks for even the smallest chips or cracks.

Question Can anyone explain how high speed steel is sharper than carbide? How is one material sharper than another? Sharpness, I've always believed, was directly related to the grit used to grind the edge. The sharpest chisels and knives I've ever seen had a final buff with jeweler's rouge. I use polished carbide blanks for inserts in CNC tooling, which give the best finish and hold an edge much longer than standard ones. Can anyone really convince me to switch to steel? Forum Responses (Solid Wood Machining Forum) From contributor M: In a nutshell, carbide is a lot harder and as a result, more brittle. That final hone crumbles the edge, whereas HSS burrs rather than crumbles, ultimately leaving a sharper edge. However, as you noted, the life of carbide is far superior to HSS steel, so your slightly duller tool is going to be slightly duller for a long time. The comparison of carbide to HSS is more common in moulder and planer work than CNC applications. Stick with your carbide inserts on the CNC. From contributor R: Well, there are some materials that you just don't want to use steel on, like MDF or plywood. They will dull steel fairly quickly. Carbide tips and inserts are composed of very fine particles that are compressed or sintered into a whole, so the finest edge or corner that can be achieved is relative to the particle size. Steel particles or grains are more homogenous, and can be shaped or polished to a finer edge. All this is on a microscopic level, so it really doesn't apply much to the person doing standard wood machining and molding, except that the carbide tooling will last much longer before getting dull. If you are doing carving or fine joinery, the polished, clean cut of steel tools is more obvious and you are not as concerned about tool edge life, because you are continually touching up the edge. I use carbide tools and inserts almost exclusively on CNC equipment, and steel tools for handwork. From contributor A: The technical answers to your questions above are right on the money. For a real demonstration, you need to use a HSS bit in a hand router. I used to make my own custom bits. The blanks are just big steel paddles. The first time I went to use one, I was a bit terrified. No anti-kickback body, just a big wing. That first cut was an eye opener! The router swept into the cut just as smooth and easy as you please. A carbide bit of similar proportion cannot compare. Carbide will certainly last longer under most conditions, but I believe we have lost much by abandoning HSS. HSS is also vastly preferable to carbide in high heat situations. For deep mortising cuts, a HSS bit will outlast a carbide every time. Excessive heat breaks down the bonding agent that holds the carbide particles together, causing the particles at the cutting edge (thinnest part) to fly off, blunting the edge. From contributor J: Carbide starts out dull compared to HSS, but just stays that way for a long time. And I'm learning (again) with the moulder that it's best for the harder woods. We profile sand everything anyway, but with ash, walnut, mahogany, etc. it does not do as good of a milling job. But you get into the hard maple and you can run for weeks without resharpening. Carbide is a godsend if you have an application that can benefit from it. From contributor B: The non-scientific explanation... Steel can be made very, very sharp because it is steel (metal/iron). It has a long-grain molecular structure that lends itself to the production of a long, sharp edge. Carbide (carbon) on the other hand, is not a metal at all, but only very hard little rocks. These individual rocks (atoms) are crystalline in structure and do not lend themselves to any kind of a long sharp edge. They're just very, very hard. Diamond, for example, is the hardest of all and is pure carbon. When alchemists and wizards eventually learned to mix the two together, they came up with an iron that is as hard as rock, but unfortunately not as sharp as steel. Why is that? The little carbon atoms are suspended within the greater iron matrix, making it very hard, but it's still the edge of steel that does the cutting. It's a compromise. They traded some of the inherent sharpen-ability of iron for the hardness of rock. HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

“No matter how hard you try, it is difficult, or I should say impossible, to collect all of the carbon dust, so copper is more suitable in these cases,” said Bond.

Milling machines specifically designed for graphite electrode manufacturing are designed with several key differences from typical machining centres, including higher spindle speeds, dust containment and collections systems, and a more powerful CNC. Photo courtesy of Methods Machine Tools.

Graphite does have limitations in its ability to achieve ultrafine surface finishes, however. These electrodes typically can produce a surface finish down to 30 μinRa/0.7 μmRa, which is sufficient for most general applications.

I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Machininggraphitehazards

When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

“There also is a combination copper-graphite material known as POCO C3 that offers a hybrid advantage of both graphite and copper,” explained Bond. “Although not as popular as in years prior, this material hybrid offers, in some cases, better wear and finish in a single electrode material.”

According to Bond, however, each manufacturer should address this issue as it relates to their own safety standards. He also advised seeking advice from the dust collector system manufacturer.

Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

“The number of electrodes needed for one job is not going to be the same for another job. Each mould has its own electrode requirements based on the complexity, accuracy, and finish of the cavities,” said Bond. “It is not uncommon to have excess spindle time on a vertical mill when it is solely providing electrodes to the EDM. Automation of the electrode manufacturing process can assist in making electrodes as demanded, and electrode manufacturing can be made ‘lights-out’ in those cases.”

It should also be noted that the use of a wire EDM to create electrodes is a slow process, when compared to conventional machining.

“It is critical to achieve both high accuracy and consistent surface finish when milling graphite electrodes, because any tooling marks, chatter, or blemishes will be reproduced on the final component,” said Pfluger.

If milling tools cannot create either the desired surface finish or geometric requirements necessary to create the electrode, a wire EDM can be used.

2. Part geometry. Most EDM electrodes are complicated parts with features that are not easily created with common tools and standard milling machines. In fact, a large proportion of these electrodes contain small, deep, and fragile features that are very difficult to create.

Carbide (carbon) on the other hand, is not a metal at all, but only very hard little rocks. These individual rocks (atoms) are crystalline in structure and do not lend themselves to any kind of a long sharp edge. They're just very, very hard. Diamond, for example, is the hardest of all and is pure carbon. When alchemists and wizards eventually learned to mix the two together, they came up with an iron that is as hard as rock, but unfortunately not as sharp as steel. Why is that? The little carbon atoms are suspended within the greater iron matrix, making it very hard, but it's still the edge of steel that does the cutting. It's a compromise. They traded some of the inherent sharpen-ability of iron for the hardness of rock. HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Milling machines specifically designed for graphite electrode manufacturing are designed with several key differences from typical machining centres. These include:

That first cut was an eye opener! The router swept into the cut just as smooth and easy as you please. A carbide bit of similar proportion cannot compare. Carbide will certainly last longer under most conditions, but I believe we have lost much by abandoning HSS. HSS is also vastly preferable to carbide in high heat situations. For deep mortising cuts, a HSS bit will outlast a carbide every time. Excessive heat breaks down the bonding agent that holds the carbide particles together, causing the particles at the cutting edge (thinnest part) to fly off, blunting the edge. From contributor J: Carbide starts out dull compared to HSS, but just stays that way for a long time. And I'm learning (again) with the moulder that it's best for the harder woods. We profile sand everything anyway, but with ash, walnut, mahogany, etc. it does not do as good of a milling job. But you get into the hard maple and you can run for weeks without resharpening. Carbide is a godsend if you have an application that can benefit from it. From contributor B: The non-scientific explanation... Steel can be made very, very sharp because it is steel (metal/iron). It has a long-grain molecular structure that lends itself to the production of a long, sharp edge. Carbide (carbon) on the other hand, is not a metal at all, but only very hard little rocks. These individual rocks (atoms) are crystalline in structure and do not lend themselves to any kind of a long sharp edge. They're just very, very hard. Diamond, for example, is the hardest of all and is pure carbon. When alchemists and wizards eventually learned to mix the two together, they came up with an iron that is as hard as rock, but unfortunately not as sharp as steel. Why is that? The little carbon atoms are suspended within the greater iron matrix, making it very hard, but it's still the edge of steel that does the cutting. It's a compromise. They traded some of the inherent sharpen-ability of iron for the hardness of rock. HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Carbide will certainly last longer under most conditions, but I believe we have lost much by abandoning HSS. HSS is also vastly preferable to carbide in high heat situations. For deep mortising cuts, a HSS bit will outlast a carbide every time. Excessive heat breaks down the bonding agent that holds the carbide particles together, causing the particles at the cutting edge (thinnest part) to fly off, blunting the edge. From contributor J: Carbide starts out dull compared to HSS, but just stays that way for a long time. And I'm learning (again) with the moulder that it's best for the harder woods. We profile sand everything anyway, but with ash, walnut, mahogany, etc. it does not do as good of a milling job. But you get into the hard maple and you can run for weeks without resharpening. Carbide is a godsend if you have an application that can benefit from it. From contributor B: The non-scientific explanation... Steel can be made very, very sharp because it is steel (metal/iron). It has a long-grain molecular structure that lends itself to the production of a long, sharp edge. Carbide (carbon) on the other hand, is not a metal at all, but only very hard little rocks. These individual rocks (atoms) are crystalline in structure and do not lend themselves to any kind of a long sharp edge. They're just very, very hard. Diamond, for example, is the hardest of all and is pure carbon. When alchemists and wizards eventually learned to mix the two together, they came up with an iron that is as hard as rock, but unfortunately not as sharp as steel. Why is that? The little carbon atoms are suspended within the greater iron matrix, making it very hard, but it's still the edge of steel that does the cutting. It's a compromise. They traded some of the inherent sharpen-ability of iron for the hardness of rock. HSS is simply a special recipe for steel that is very heat resistant. It works best in almost all rotating machinery, but it ain't as hard as rock. Sometimes you need those little rocks to support the edge of the steel because the steel often comes in contact with stuff (silicates/dust) which is harder than itself. Carbide steel, though, is dull compared to pure (say, surgical) steel. Steel still requires a little more sharpening to maintain its razor edge. Fortunately it sharpens easily with regular stones (and not diamonds). Unfortunately the high speed of machinery also translates into high heat. Heat vs steel is like Kryptonite to Superman. Heat erodes and destroys the sharp edge of steel but leaves the carbon sticking up. Now the razor blade knife edge is blunted, but not dead. This is the compromised edge of carbide steel that seems to work and last longer (but not necessarily better). Experience dictates which is truly better, but don't fall into the mindset that everything now needs to be carbide. Diamond is the newest hyperbole that we all definitely must have. I am not buying it. From Dr. David Rankin, forum technical advisor: This is a very good question, and many good answers. HSS will sharpen sharper than carbide. I explain it this way. Carbide is a powderized metal made up of a bunch of ball bearings. The size of the bearing determines the sharpness of the carbide. As soon as you run the carbide, the first row or two of the balls break away, but then holds up well for a long time (in comparison to normal HSS). As stated in an earlier post, heat is the enemy. Heat can be reduced on a cutting tool by several things. You can add a lubricant to the tool and this can help. This is done on saw blades for many applications. The lubricant acts as a coolant. I have seen this increase the tool life several times the normal expected. Lubricants work well on HSS and carbide. It is important that the lubricant used on carbide is designed for carbide so that you do not break down the cobalt binder in the carbide. I use special coatings for tools that reflect heat. Many years ago I patented a coating that has proven to extend tool life 6-10 times for HSS and 3-4 times for carbide. This coating does not eliminate the balls breaking off of the carbide but does help carbide hold that running edge for an extra time. In the case of HSS, the coating reflects heat of 2200ºF and is harder than carbide. We have run moulder runs of 6 - 8,000 lineal feet in many MDFs. This does not replace carbide but is a good middle range tool between normal HSS and carbide. Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

“Investing in a machine to do 0.002- to 0.003-in. electrode tolerances requires a much greater investment cost than [if] a few tenths’ looser tolerance [is all that’s required]. It all comes down to tolerance,” said Bond.

1. Tool wear. Because the graphite materials used for EDM work are very abrasive in nature, uncommonly fast tool wear is the reality. While even standard high-speed steel (HSS) cutters can machine this graphite, they will exhibit high wear characteristics, making high-accuracy dimensional control and good surface finish quality difficult to maintain.

The combination of high feed rate, small-diameter cutting tools, and difficult-to-cut graphite requires milling machine spindle speeds of 20,000 to 40,000 RPM for optimal performance.

Milling graphitepdf

“The idea of using flood coolant is attractive for the milling of graphite electrodes, because it would cut down substantially on the amount of graphite dust that is produced, but the reality is that this is not practical,” said Pfluger. “If a graphite mill is to be dedicated solely to producing graphite electrodes, then an EDM dielectric fluid can be used for flood coolant. The use of EDM dielectric fluid as a coolant within the milling machine will require other modifications to the coolant filtration system, because graphite dust will clump and cake up, which could clog a standard coolant system.”

Dec 3, 2003 — Single point tools are cheaper, much cheaper. That's important in my shop. You can use one single point for a number of different thread types.

Copper-tungsten electrodes also are available, but typically have a higher cost and must be used at slower machining speeds. These are typically reserved for cutting graphite.

For simplicity and reliability, it is recommended to mill graphite electrodes dry using a high-performance dust collection system, added Pfluger.

“Graphite provides an economical way to manufacture electrodes and creates a very stable EDM process with, in most cases, less wear than other electrode materials,” said Steve Bond, national sales manager of FANUC Robodrill, Robocut, and EDM products for machine tool distributor Methods Machine Tools.

PVD is a thin film deposition process in which atoms or molecules of a material are vaporized from a solid source in high vacuum and condense on a substrate.

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A compact Erowa robot tends a Makino EDNC6 sinker EDM and a V33i-5XB Graphite 5-axis vertical machining centre to produce electrodes with complex geometries, which are then automatically fed to the EDM. Photo courtesy of Makino.

“This means of graphite electrode manufacturing will not be the quickest, but there are specific circumstances in which using a wire EDM to cut the graphite makes sense,” said Pfluger. “If a graphite electrode’s geometry requirements, such as very small inside corner radii, are beyond the milling machine’s spindle RPM, then using wire EDM as an alternative manufacturing method makes sense. The use of wire EDM to machine graphite electrodes also is beneficial for small or thin features that might be unstable or too fragile to mill.”

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“The key is to identify the slowest process in a manufacturing cell, because the capacity of the slowest bottleneck will dictate the overall productivity and output,” said Pfluger.

- CNC power. Graphite machining centres need controls that are powerful enough to handle the processing of the large amount of data that is typical in highly complex part programs.

“If the moisture is not removed before EDM work begins, it will superheat during the erosion process and expand, causing the electrode to chip or fracture,” said Bond. “Removing the moisture can be achieved by simply putting the graphite in an oven for a few hours to dry it out.”

Joe Thompson has been covering the Canadian manufacturing sector for more than two decades. He is responsible for the day-to-day editorial direction of the magazine, providing a uniquely Canadian look at the world of metal manufacturing.

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- Higher spindle speed. Higher spindle RPMs are needed for the fast program feed rates and small-diameter cutters that are commonly used.

One of the biggest challenges facing shops that perform EDM work, especially those manufacturing moulds, is ensuring that the EDM is not waiting for the milling machine to complete its task, or vice versa. Because the manufacturing of electrodes typically is much faster than the EDM work, this can be difficult to manage.

I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Another thing to consider is the type of grinding wheel you are using to sharpen your HSS and carbide. Carbide being a man-made material requires the correct diamond wheel. Many grindermen use a wheel that is not fine enough to produce the quality of finish desired. Also the coolant used is a major concern. Carbide requires a coolant that does not leach the carbide. (This is where the binder is damaged.) Clean coolant is critical in both HSS and carbide. From contributor B: Dr. Rankin, I've always considered spray coatings to be kind of a gimmick, especially for router bits that are rotating at 20,000 rpm! I do understand how some coatings can reduce the buildup of pitch and resins on cutting tools, but I am skeptical of any coating's ability to actually adhere to the cutting edge (while it's cutting). I am also skeptical of your claim of a coating which is harder than the carbide itself (diamond mist?). I do understand how cutting coolants and lubricants are essential in machine tool applications, but liquid lubricants are not practical in woodworking applications. So I am a doubting Thomas here, but I hope you can convince me that there really is such a thing as a magical mist that I can believe in. From Dr. David Rankin, forum technical advisor: The coating that I use is not a spray, it is a vacuum process. We take the knife steel or router bit to 275ºF in a vacuum. We then explode a series of targets onto the steel. These targets are made of several materials (I am not at liberty to release this info). The coating I use is made up of several layers. Without giving out trade secrets, I will try to provide you some info. One layer increases the lubricity of the substrate, in this case reducing the buildup of pitch or other similar byproducts. One layer reflects heat, much as a heat sink in electronics. One layer is called a diamond like coating and in comparison to carbide is about 20% harder. The total coating is only 4 microns thick, so flacking of the coating has not been a problem. I can totally understand the concern about coatings and tool treatments. When I started the research in the late 1990's, most of the coating processes produced a thick coating that would flack. As for treatments or sprays, the results depended on the material being cut, the amount of spray and several other factors. In the last 10 years, I have used a couple of good sprays and systems that got the spray to the correct placement. However, sprays are not useable in all applications. When I first patented the DGK coating, we found that in solid woods we could increase the life of the tool by over 6 times. I did the original tests in Mississippi at a long time customer. During the test we ran at 150 feet per minute jointed on hardwoods. I stopped the feed and let the knives (6 wings) run onto maple. After 5 minutes the wood was very close to burning, while the tool's temperature was under 110ºF. When the feed was restarted, we had not lost joint and the tool ran the remainder of the day. This customer has run DGK since 2000 and has had consistent results. A couple of secrets: Grind with a ceramic or CBN wheel Do not hone the face of the tool In the case of router bits, recoat after sharpening. When moulder, planer and shaper knives, you do not need to recoat as the coating in on the face of the tool. From contributor V: One point that has not been noted is that the wedge angle must be larger for carbides than steels. Thus we can grind to a keener edge in steels - if we did this in carbide the edges would break off, as it is too brittle. When machining solid woods, steels will always have an advantage in the edge produced. We go to carbides where tool lifetimes are more important than finish qualities - especially in man-made materials. They both have uses - good suppliers can steer you to the right knife materials based on the intended uses. From contributor A: It is well worth noting that quality and grade of carbide varies. The micrograin carbide from CMT is sharpened to close to HSS sharpness, and if used on MDF, there is no comparison after even a little use, as HSS is very poor cutting anything slightly abrasive. Good quality micrograin carbide, kept clean (which helps the blade to eject waste better and consequently keep cool) holds its edge far longer than standard carbide.

Generally speaking, any dust can be an explosion hazard. However, the dust generated during the electrode manufacturing process typically is dense enough that it does not require explosion-proof collection systems.

“These added features prevent the graphite dust from contaminating and damaging the machine’s spindle and ball screws, and they also prolong the functional life of the machine way covers,” said Pfluger.

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“Depending on part requirements, the use of graphite during roughing provides faster machining speed with less electrode wear. Then copper electrodes are used during finishing to create finer surface finishes and less electrode wear, providing the best mix of speed and performance for sinker EDM applications,” said Pfluger.

4. Dry material. Graphite is a porous material that absorbs moisture, which will cause problems downstream during the EDM process.

“If the graphite dust is not controlled and collected properly, it can pose a health risk to the operator, and can lead to damage within critical mechanical components of the milling machine, such as the spindle, way covers, and ball screws,” said Pfluger.