I think you left out force vectors during cutting. This can influence tool defection and taper on the side wall on the part. The force vectors are different magnitudes between climb and convectional cutting, so this impacts work holding and this parts or this walls.

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There can only be one way to interpret the cut because machines only turn in one direction. In the examples the view has to be from under the workpiece looking up at the tool

However, it would be best to exercise caution when using carbide-tipped drills since they can be brittle despite being the hardest. Because of their great strength, they are extensively employed in industrial applications. They can cut through concrete, masonry, tile, and hardened steel.

However, though Climb Milling is often the current preferred way to machine parts, there are times when Conventional Milling is the necessary milling style. One such example is if your machine does not counteract backlash. In this case, Conventional Milling should be implemented. Without accounting for backlash, breakage can occur due to the forces within the machine during tool engagement.

The drill speed is critical for drilling hardened steel. Drilling at high speeds causes high temperatures, which will damage your drill bit. Therefore, drilling hardened steel should be done at a low RPM and feed rate. Feed rates are typically at least 50% lower than for lesser hardness steel. Speeds generally are 30% of that of a non-hardened material.

When drilling through hardened steel, you must ensure that your drill bit is made from tougher materials. Carbide bits are the strongest drill bits material and can cut through hardened steel. But if they are not available, titanium and cobalt drill bits can also be used. However, drilling with either of these bits will take longer than drilling with a carbide drill bit.

Titanium drill bits are high-speed steel bits with a titanium nitride (TiN) coating, whereas cobalt drill bits do not have a coating; the entire bit is constructed of alloy steel that contains 5 to 8% cobalt.

That is not to say there aren’t benefits to climb milling. For example, this strategy offers a machinist more control and less vibration than its climb milling counterpart. Similarly, for materials that traditionally chatter or tear, conventional milling would be the proper strategy to choose. On the other hand, here are some reasons why it might be most beneficial to adopt a climb milling strategy:

Plainmilling

Therefore, cobalt drill bits have a longer life and are more heat resistant than titanium drill bits. Which means cobalt drill bits are typically better since they are much more durable than titanium-coated bits and can drill holes through the hardest metals.

A 60 year old worn out manual Bridgeport is all I have to work with. (It is in better shape than my 65 year old worn out body.) I rarely climb mill anything, specially not steel. But if the cut is really light, and I want a good finish, I climb mill. , I apply some drag with the table lock screw, and that seems to eliminate the chatter.

Facemilling

There are two distinct ways to cut materials when CNC milling: Conventional Milling (Up) and Climb Milling (Down). The difference between these two techniques is the relationship of the rotation of the cutter to the direction of feed. In Conventional Milling, the cutter rotates against the direction of the feed. During Climb Milling, the cutter rotates with the feed.

This is great info. I have always conventional milled with face mill to remove the scale off of titanium. Tool life is increased and getting under that scale to machine it off instead of slamming the insert into the scale each time. Once scale has been removed, go back to climb cutting.

Carbide drill bits are the toughest drill bits available and best for drilling hardened steel. Carbide is a  compound made from tungsten and carbon. Carbide drill bits are typically composed of steel that has a carbide tip.

As previously stated, traditionally conventional milling has been the common choice for most machinists. This is where the cutting edge of the tool is actually rotating away from the direction of the feed. An example of this is seen in Figure 2 below. Until recently, this has been the common choice due to backlash however, the rise of climb milling has caused machinists or machines to adapt and compensate for this issue.

Advantagesanddisadvantages ofup milling and down milling

Thanks for this very clear and informative explanation. It has been decades since I worked in a factory. Back then the Bridgeport milling machines had terrible backlash. They would chatter or jump when using climb milling. Plus, if one was approaching the end of a cut, one wouldn’t know if the tool would grab at that point and pull the work past the past the desired end point. I almost exclusively used conventional milling and couldn’t understand why many people on YT now talk about using climb milling.

Up and down millingpdf

Cobalt drill bits are not made of pure cobalt. Instead, they are made of steel combined with a small proportion of cobalt, often between 5 and 7 percent, and the remaining part steel.

Measure and mark the hole, then use a center punch and hammer to make a slight indentation. Drill bits tend to wander when they first start drilling. Therefore the dimple helps the drill bit become more steady. The dimple also serves as a reference for where to drill your hole.

It depends on your perspective. Are they showing a view looking down at the work piece or looking up from the workpiece.

Have seen this article several times. One consideration is roughing, my observation is that the load against the cutter when cutting in the conventional direction is lower and reduces the risk of tool breakage. Another is where the tool-paths leave “posts” in corners and so-fourth when hogging out parts, conventional milling will not grab into a post and break the cutter. Another application is when making long thin flats in rod shaped parts either on a indexing head or on a swiss type automatic lathe through a guide bushing, the conventional path will produce less taper and more parallel surfaces. Just a few thoughts.

Cobalt has a high melting point of 1495°C, making it ideal for high heat drilling applications like hardened steel. The most common are M35, a 5% alloy, and M42, a 7% alloy.

If you are short on time, the best drill bits for hardened steel are carbide-tipped bits. They are the most suitable drill bits for hardened steel due to their robust and heat-resistant properties. However, there are other options such as titanium and cobalt.

Hardened steel is used in energy,  transportation, general mechanical engineering components, and many other applications. Axles, arbors, driving pinions, camshafts, and Cardan joints are examples of hardened steel components.

Carbide drill bits are typically harder than cobalt drill bits, although both are suitable for drilling stainless steel and other hard metals. However, Carbide drill bits retain their sharpness for a longer period than cobalt drill bits. They can also be utilized at a faster cutting rate and withstand higher temperatures than cobalt drill bits.

As machinists are always trying to find ways to increase efficiency and tool life, climb milling has gotten a lot of recent traction in the space. Less heat is generated within the tool, and friction is more easily mitigated. These two alone lead to longer tool life, allowing for more parts completed per tool, lowering a shops bottom line. Also, climb milling can lead to a better surface finish due to how the chips are formed at the cutting edge.

Conventionalmilling

Up milling and down millingwhich is better

With more modern machines now compensating for backlash or utilize backlash eliminators, it has become a much easier strategy to adopt within shops. While we went over some reasons why climb milling is not an effective strategy above, here are some reasons why a machinist may want to explore climb milling:

There are many other things to consider when choosing the right drill bit for hardened steel. This post will cover what you need to know about drilling hardened steel and provide you with some suggestions on the best drill bits that will work well for your needs.

I have a Warco 16B milling machine. This is a medium size manual hobby mill. I am confused as people recommend Conventional and Climb milling in about even numbers, this goes for YouTube too. What would you recommend on this type of machine? Your help would be appreciated as I last worked in industry in 1979 so I am extremely out of date. I generally mill Conventionally.

Titanium nitride (TiN) is a very strong ceramic substance that protects the steel bit and allows it to last longer, especially when drilling hardened steel.

Conventional Milling is the traditional approach when cutting because the backlash, or the play between the lead screw and the nut in the machine table, is eliminated as seen in Figure 1 below. Recently, however, Climb Milling has been recognized as the preferred way to approach a workpiece since most machines today compensate for backlash or have a backlash eliminator.

Drill through-hardened steel metal at the recommended speed using a drill bit, preferably carbide bits. Larger drill bits require even slower speeds.

Great explanation of the differences between climb milling and conventional milling! I appreciate how you highlighted the advantages of climb milling, especially in reducing tool wear. It’s very informative for someone looking to refine their machining techniques. Thanks for sharing!

When comparing the carbide, both cobalt and titanium drill bits are better than regular steel drill bits due to their added components, as well as their resistance to heat and wear. However, in terms of hardness and longevity, the carbide drill bit is better than both of them.

Added uses for conventional cutting: Never climb cut across the end of an upstanding thin rib in aluminum or plastic (You will rip it off). Use reduced feed and conventional cut it or use multiple small depth cuts. Commonly made cutting to length T or L extrusions. You’ll only make this mistake once. It helps to conventional cut torched or burnt out steel plate rough profiles first, then switch to climb cut after you mill through the slag. Same principal as case hardened material. Corn-Cob or serrated cutters work nice here too.

Hardened steel types include ATS34, CPM440V, Z60CDV14,  Sandvic, and 12C27. Carbon steel must go through a succession of heat treatments, quenching, and reheating to become hardened steel.

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Hey there, first of all thank you so much for this post and honestly I was searching for the same information from last few days. Keep posting and keep sharing..

If you are in the process of drilling hardened steel, maybe for one of the reasons mentioned above, or potentially something completely different, why not take a look at the drill bits we have available for metal. Our range is designed for high end performance and is suitable for those drilling hardened and normal stainless steel.

This is one of those left hand cutters! How about turning the tool, and cutter the correct direction. G41 climb cutting on the right side. G42 or conventional cutting on the left. Sorry I couldn’t help myself.

Rockwell hardness testing is a standard method for determining the  hardness of metals and polymers. Rockwell hardness is measured with a device known as a Rockwell hardness tester. The tougher the steel is, the higher the number on the RC scale. The higher the RC number, the slower the drill speed should be.

Climb Milling is generally the best way to machine parts today since it reduces the load from the cutting edge, leaves a better surface finish, and improves tool life. During Conventional Milling, the cutter tends to dig into the workpiece and may cause the part to be cut out of tolerance.

Great article. I’ve had to use conventional milling when for example, I’d have my thin unsupported part sticking out of work holding with the tool path contouring around the part (think milling end while cutting a part in a lathe) with the material flexing would cause snapping while climbing because it wants to take a large bite as opposed to ramping the cut in. But yeah, 95% or more is climbing.

Climbmilling

Thank you for the question Dustin! We would suggest conventional milling when your material has a rough surface, such as cast iron, or is anodized because when conventional milling your cut is scooping underneath the surface to remove your material making it easier on your tool. Also, you want to conventional mill when using a dovetail cutter that has a weak neck diameter because this will help relieve the pressure on the neck of your tool.

In addition, conventional milling should also be utilized on casting, forgings or when the part is case hardened. This is due to the cut beginning under the surface of the material, where it will gradually build a chip. Climb milling into these materials will see maximum chip thickness on engagement, which could lead to premature failure of the cutting edge due to the forces generated. print

Titanium drill bits are high-speed steel bits with a titanium nitride covering. Titanium-coated drill bits provide many advantages over ordinary steel bits, including the ability to endure greater temperatures, increased wear resistance, and higher durability.

Great question Graham! There are many factors that go into choosing which method is best for you. Please send an email to [email protected] with all your information and they will be able to help you out as soon as possible.

“Conventional Milling should be… utilized on casting, forgings” In my head, I logically organize castings as least processed, forgings as most processed, and everything else (hot rolled, cold rolled, extruded) somewhere in between. So to me, that part seems to say ‘use conventional milling for everything’, which is obviously not right. Could you show me where I went wrong,? More specific examples, like case hardening, why a particular direction of cut is preferred for a chunk of metal with unknown provenance.

I like what you said about chip width working. I need a milling machine for some steel. I’ll have to get a dye-cutter that is discounted.

Carbide drill bits are used for drilling broken bolts, safes, studs, bearing races, taps, and knives made from hardened steel. They are designed to allow the quick dissipation of heat and prevent chipping.

For better protection, use safety glasses that wrap around the sides of your face. Eye protection is required to ensure that a tiny metal fragment does not cause significant eye injury.

Up and down millingprocess

Lubricant should be applied to both the drill bit and the drilling surface. To reduce the temperature, repeat this step between drillings.

Make sure the piece of metal is in a flat and secure area. Holding the metal with one hand while running the drill with the other is not a good idea. It is better to secure the metal with a clamp.

If you've worked with hardened steel before, you'll know that a regular drill bit won't cut through. Your best bet is to use the carbide bits because they are the hardest drill bits available.

In computing for the RPM, for example 1"-diameter tool must run at 30 sfm. Based on the equation above, at 30  sfm: (30 × 3.82) ÷ 1 = 114.6, this means you have to use 115 RPM to drill a 1 inch Rockwell C 40 to 45 steel.