For deeper, large-diameter applications, the Iscar ModuDrill is a combination of replaceable head and indexable insert drills in larger diameters for depths beyond 12×D. The ChamIQ 700 family is offered in a diameter range of 33-40 mm in 0.5 mm increments and “some common fractional-inch increments,” he said. “The HFP carbide blades, which look more like a spade drill, fit into a range of steel adapter heads (MD-DFN), which also mount onto a long steel drill body (MD-BODY). A combination of two drill bodies and seven adapter heads cover the entire diameter range.”

It’s easy to compute Feeds and Speeds to compare these two face milling solutions using our G-Wizard Calculator software (click the link for a free 30-day trial if you’ve never played with G-Wizard).

Louis, thanks for raising that issue. You’re quite correct about the 45’s higher axial forces and the issues they may cause for a workpiece that is not well supported or perhaps that is simply a bit thin.

I keep a 2″ diameter 90 degree facemill in my shop as well as a 3″ Glacern FM45 45 degree face mill. The FM45 sees a lot more use for sure.

Replaceable-tip cutting tool suppliers offer numerous examples of how those tools surpassed solid-carbide versions. For instance:

I selected my machine, workpiece material, and indexable tool type.  I’m modeling a smallish 2″ diameter face mill with 4 inserts, and I have set the Lead Angle to be 90 degrees.  My Cut Depth is 1/8″.

PVD coatings are most common for smaller diameter tools, he added, “because they help maintain sharper edges than thicker CVD coatings. Kyocera’s R&D efforts in PVD coating technology have resulted in our Megacoat coatings. With high oxidation temperatures and high hardness, they are ideal for running at higher speeds, resulting in reduced cycle times.”

“Clearly, a small replaceable insert or tool head made of carbide costs less than an entire solid drill of the same diameter,” noted Andrew Pisorn, solid carbide product manager at Allied Machine & Engineering Corp., Dover, Ohio. And, by extension, using a range of replaceable-tip tools with a smaller number of steel body holders greatly improves operational and cost efficiencies by cutting down on one’s inventory of unique solid-carbide tools. “If your shop can minimize the amount of carbide in your tool cribs and drawers, you’re minimizing inventory costs.”

Yes!  The angle is the angle of that cutting edge–45 degrees for the cutter on the left and 90 degrees for the one on the right.  That angle is also called the lead angle of the cutter.

Also for hard-to-machine materials, Sandvik Coromant’s recently introduced CoroMill 316 exchangeable milling heads are optimized for titanium and nickel-based metals. For titanium, grade 1745 with its 1.5×D cutting edge “is a little bit longer of a replaceable-tip end mill compared to our standard 316s,” explained Scott Lewis, aerospace industry specialist for Sandvik Coromant. To be released in the near future is grade 1710 for nickel alloy, which will also have 1.5XD capabilities. Both grades feature unique substrates and geometries and are currently available in the company’s solid-carbide end mills. These replaceable-tip end mills “can run, cutting data wise, quite close to what a solid is, with a solid being perhaps more rigid because it is shorter—a stouter setup,” Lewis said. “We also have very short, stout adapters for our 316s.”

When drilling difficult-to-machine materials like stainless steel or titanium, steel bodies for replaceables might torque too much, Pulvermacher cautioned. For that reason, fabricators have tended to split their use of solid and replaceable tools for those materials about 50-50, depending on the diameter. For that to change, he said, replaceable-tip tools would have to outperform solid in the 0.5-0.75" (12.7-19.05 mm) range. Replaceable-tip drills might get the nod in larger diameters, where solid drills could cost up to $750; however, replaceables struggle under 7/16" (11.11 mm) because they are somewhat expensive relative to solids—and the small tools, screws and inserts tend to get lost.

YG-1 touts its 7×D drill as the only one of its type on the market, Pulvermacher noted. “People really like it because 8×D gives up so much rigidity.”

Use of Wiper Inserts can greatly improve the surface finish when Face Milling.  High feed rates and low depth of cut (0.8mm or less) will facilitate this.  PVD (diamond) inserts with very sharp edges can also improve your surface finish.

First, what are we talking about when we say 45 or 90 degrees?  The answer is fairly obvious from the photo above comparing two Glacern cutters.  Take a look at the angle of the cutting edge on the inserts.

Let’s start by choosing the best type of Face Milling Cutter for your Face Milling needs.  The biggest differences between Face Milling Cutters are:

The modular part of the system “is that there are indexable insert heads that also mount onto the two drill bodies,” said Ewing. They are offered in eight metric sizes (33-40 mm) and two inch sizes (1.375" and 1.5") and use standard SOMX inserts from the DR Twist line. “They also use guide pads from the BTA Deep Drill line. The drilling depth of this system is in the 16.5-17" [419-432 mm] range.”

Slated for release midyear is YG-1’s I-One drill. “We’re performing extensive testing with it in the energy industry, with very good success,” Pulvermacher noted. It will exist alongside the company’s well-established I-Dream drill, which currently has several geometries: Dream Drill General for general purpose (carbon steel, iron); one for stainless (Inox); Dream Drill Alu (aluminum), High Feed (carbon steel, iron); and High Hard (up to 70 HRC).

I can do that since I will use a toolpath that arcs gently into the cut and I will arc the end of each pass to avoid a sharp corner and also to avoid completely leaving the cut.  Those are CAM toolpath tricks that can really help you out on tool life, surface finish, and in this case, they let you opt for a big increase in feeds and speeds too.  If your CAM won’t do those things the Conversational CNC Face Milling Wizard in G-Wizard Editor will do them very easily.

Another inventory factor to consider: Shops that routinely send solid-carbide tools for regrinding must keep an adequate supply of solid tools in reserve to maintain production, said Patrick Loughney, a product manager at Sandvik Coromant, Fair Lawn, N.J.

But what about performance? Ultimately, using replaceable-tip drilling tools generally does not mean sacrificing much penetration rate or tool life—to a point—experts assert.

Of course if you can afford it, it’s great to have both 45 and 90-degree face milling tools, but what are the pros and cons for each?

The Button Cutter (also called a Copy Mill or Toroidal Cutter) uses a round insert and has many advantages of its own.  Tough to call a winner with a Button Cutter versus these other Face mills, so click through and see about Button Cutters in their own right.

Meanwhile, Kyocera Precision Tools Inc., Hendersonville, N.C. is noting increased demand for smaller, modular indexable end mills, said Technical Center Manager Brian Wilshire.

To more than double the depths of cut previously available in its Multi-Master line of end mills, Iscar Metals Inc., Arlington, Texas, added replaceable-tip mills capable of reaching depths up to 1.5×D, said Tom Raun, chief technical officer.

Technically, that’s face milling, though we typically only refer to it as face milling when we are using special milling cutters called “Face Mills” or “Shell Mills”.  Note that there is literally no difference between face mills and shell mills.

Now we see why the 45 degree models are so popular–that’s more than 40% more material removed.  That’s definitely going to pay for the new face mill pretty quickly if you’re using it for very many parts.

“The biggest thing we’ve done is introduced new grades optimized for steel, stainless steel and cast iron,” he continued. “Our Zertivo technology uses a PVD process, and we are able to achieve better bonding between the substrate and coating to where we have significant improvements in edge line security—resulting in longer, predictable tool life.” Grades include –PM 4334 for low alloyed and carbon steels, –MM2334 for stainless and –KM3334 for cast iron. While there is no grade specifically for heat-resistant materials, Loughney added, “we can cross over our geometries into those areas” for multiple industries.

You can get a face miling cutter in a wide range of cutter diameter.  What you want to do is balance 2 factors.  First, the bigger the better.  It will take fewer passes, and ideally maybe even a single pass, which is best for surface finish.  Number two is the counter point to number one.  You must respect the horsepower and rpm limits of your machine.  The bigger the cutter diameter, the more power it takes.  I will also add that spindle speed can be a limiting factor.  In general, larger cutter diameter cutters have to spin at lower rpms, while smaller cutter diameters can spin at higher rpms.

Jim White, national sales manager for Carmex Precision Tools LLC, Richfield, Wis., concurred. “The reason most customers go with indexable is versatility—using one holder for multiple pitches—or cost,” he said, adding that “indexable thread mills are more cost effective in large-thread diameter applications or low-volume jobs where cycle time is not a consideration.”

These drills are being used heavily in structural steel applications like beams and bracketing in areas such as bridge towers, Pisorn said. Planetary gears with flanges might feature 20 to 50 shallow holes; bearing rings for wind energy can feature 50-100 holes. Tube sheets for heat exchangers is another sound application. And, a filtration system plate for the paper industry might feature thousands of shallow holes.

On the larger side, Iscar’s LogIQ-3-Cham is a three-flute, interchangeable-head drill in 14-23.9 mm diameters, in 0.1-mm increments and bodies in 1.5×D, 3×D and 5×D. “Eventually, the line will include all head sizes from 12-25.9 mm. The three-flute design will provide extended tool life and/or increased feed rates,” mostly for ISO-P and ISO-K materials, Ewing said.

Replaceable-tip tools can also provide users with a significant reduction in setup times, Loughney added, for instance on transfer lines for automotive manufacturing. And, with the ever-pressing shortage of experienced manufacturing labor, quick and easy tool switchouts instead of more intensive setups help ease that burden.

As a result, the DIAEDGE STAW demonstrates “excellent chip disposability and achieves high-efficiency machining,” Griggs noted. “STAW replaceable carbide tips/inserts are designed for extreme sharpness, precision, positioning and rigidity in our unique clamping system. The wavy edge design delivers a sharp peripheral edge to enhance cutting performance, complemented by a strong center point geometry for initial cutting at entry. A high helix offers a low-resistance drill pocket design that improves chip breaking for superior chip disposal.” The STAW’s clamping system has more material behind the tip for added strength and durability.

Another drill that’s been on the market a while is the CoroDrill 870 series by Sandvik Coromant. But since its introduction in 2012, numerous refinements have been made. “We found that the body material was wearing, so we made it more wear-resistant, making the drill more rigid,” explained Loughney.

Bob is responsible for the development and implementation of the popular G-Wizard CNC Software.  Bob is also the founder of CNCCookbook, the largest CNC-related blog on the Internet.

The current crop of replaceable-tip milling and drilling tools features a host of new substrates, geometries, PVD coatings and coolant solutions geared for a range of applications across numerous industries and materials. As always, the decision to use a particular tool is application specific.

Allied’s new GEN3SYS XT Pro drills feature dual gundrills with four outlets for increased coolant flow and material-specific inserts with coatings developed in-house. “A unique connection design offers superior torsional loads while still allowing the convenience of insert swaps while the tool remains in the spindle,” Pisorn said.

Of course you can use end mills for surfacing, but it is seldom optimal to use an end mill.  There are two major problems using end mills.

One last thought about face mills–they’re horsepower hogs. Don’t try to use too large a face mill on your machine. I’ve stalled the 3 horsepower spindle of my mill running my 3″ pretty easily.  Granted, it’s a smaller mill, but you need to keep in mind even if you have plenty of spindle power that the face mill is going to transfer a whole lot of it into your workpiece.  Make sure it’s clamped down tight!

If you’re primarily after a great finish, then you probably want a fly cutter.  The lowly fly cutter gives the best finish in most cases.  BTW, you can easily convert any face milling tool to a fine fly cutter by simply removing all but one cutting edge.

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For large-diameter applications, true helical flutes are the key to the success of the SRH series of replaceable mills by Carmex, said White. Helical flutes cut freer than straight-flute tools, he explained, although “solid thread mills are still the most efficient choice for anything under 1" (25.4 mm) thread diameter because you get more flutes in the cut and the geometry allows for higher cutting speeds and faster feed rates.” The SRH has been most successful in the oil and gas market, threading buttress and Acme threads in large diameters, he added.

First, end mills are generally smaller in diameter.  This means it will take many more passes to do the job and all those passes will leave that many more marks on the work.  The end result is end mills will take longer and they will have a much less fine surface finish.

However, any time an operator makes changes in the machine, something can always go wrong. For instance, they must take care not to drop wrenches and screws into the machine while replacing tools.

By the way, round insert cutters are also called “Button Cutters”.  We have an entire article about Button Cutters if you’re interested.

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What is Face Milling?  Think of milling with the side of an end mill.  The general term for that is “peripheral milling”.  Now, what if we cut strictly with the bottom?

SumoCham is available from 4-32.9 mm diameter in 0.1 mm increments, Ewing explained. Heads are offered in 10 geometries for various material groups and applications, and bodies are offered in 1.5×D, 3×D, 5×D, 8×D and 12×D through most of the diameter range. Each body accepts a range of head diameters: from 4-14.9 mm, bodies come in 0.5 mm increments, and from 15-32.9 mm, bodies come in 1-mm increments.

Try to roll into the cut with an arc.  It will improve your finish as well as your insert life.  More toolpath ideas here.

The Mini-Mill series of tools—including Nanmill, Nan3feed, Heli4mill, Heli3mill and Micro3feed—complement Iscar’s solid-carbide tools with diameters starting at 0.312-0.75" (7.92-19.05 mm) with multi-edged inserts for 90o milling and fast-feed milling, he explained.

In terms of drilling, the number and type of holes to be made is generally the key determinant for opting to use replaceable-tip tools, according to Allied’s Pisorn. The more holes (from 1,000 to 50,000 or more) and the shallower (up to 13×D) the better.

If you’re on a CNC Router, a very common operation is “Spoilboard Surfacing“, and while the router crowd likes to call the milling cutters used for Spoilboard Surfacing “Spoilboard Cutters”, they’re just another form of Face Mill.

Toolholding is vital to precision holemaking with replaceable-tip drills, he continued. “You have to remember that you have collective tolerances—of the body itself and then a tip on top of it.”

Lately, you can get some face mills that use a 45 degree insert that’s double sided, so we have the best of both worlds since these inserts now have 8 edges like the octagonal inserts.

Be careful where you use 45 and 90 degree cutters. A workpiece that is not well supported, will deflect under a 45 degree cutter due to the high axial forces. A 90 degree cutter will produce a more consistent cut and the corresponding decrease in chatter will extend the life of the cutter.

“Various grade options allow better flexibility and optimization vs. solid carbide tools” and feature proprietary Sumo Tec PVD post-coating technology that provides “improved toughness, improved flaking, and chipping resistance, which in turn provides very reliable and repeatable results.” Those grades are:

Louis, thanks for raising that issue. You’re quite correct about the 45’s higher axial forces and the issues they may cause for a workpiece that is not well supported or perhaps that is simply a bit thin.

If there’s a slot or other recessed feature in the surface you’re Face Milling, you’re going to be doing some interrupted cuts.  This is hard on the inserts, so if you’re dealing with a tough material, you may want to reduce the feedrate up to 50%.

Other alternatives include 75 Degree Face Mills and Button Cutters (Round Insert Indexable Mills).  The 75 Degree Face Mill’s primary purpose seems to be providing just a bit more clearance than the 45 degree can.  It might be your 3rd or 4th choice if you already have a 45 and 90 and want more options for difficult cases.

The initial release of the I-One will feature a single grade for the energy industry, with general-purpose grades and geometries to follow. I-One’s multilayer coating is geared to high or low speeds and is designed to tolerate heat and abrasion and prevent sticking. It is fully coolant-through.

At one time, octagonal face mills were at war with the 45 degree face mills for supremacy. The octagonal inserts have more edges, so you can rotate the insert if one gets chipped. But, tooling costs are usually only about 3 percent of the manufacturing cost, so the greater efficiency of the 45’s eventually won out.

“For example, if I would expect to get a thousand inches of tool life with a solid, then I would expect the same from a modular tool—but of course exceptions apply,” said Bill Pulvermacher, director of marketing for YG-1 Tool Co., Vernon Hills, Illinois. “I would expect the overall penetration rate of the solid to be just a little bit higher.” Furthermore, some users say replaceable-tip drills over 0.5" (12.7 mm) tend to perform better in lathe applications “because they are much more tolerant of the misalignment that lathes tend to have.”

Fabricators seeking smaller diameters can look to Iscar’s SumoCham line, now available down to 4 mm in up to 5×D applications, said Craig Ewing, national product specialist for Iscar Metals.

“Some smaller sizes come in smaller shank diameters and shorter OAL (overall length) without a flange for Swiss lathe and live tool applications,” he added. “There are also drill bodies with integrated chamfering inserts.”

XT Pro carbide inserts have a combination of substrate coating and geometry engineered to survive the wear of high-penetration drilling, which “inherently produces significant heat,” Pisorn noted. “Combating that heat well is critical to extending tool life and increasing drilling rates. We have worked closely with our coating team and partners to develop several new material-specific, proprietary, multilayer coatings designed to withstand increased heat thresholds.”

Now, we can check out the 45 degree face mill / shell mill just by changing the lead angle to 45.  Let’s assume every thing else stays the same, here are the results:

When weighing the choice of replaceable-tip mills and drills or solid-carbide tools, consider this succinct statement from one industry expert: carbide equals cost.

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And lest we forget button cutters, they combine some of the advantages of each plus they are also the strongest.  So if you have to deal with nasty materials, a button cutter might be your best choice.

Inserts are available in sizes from 10-18.1 mm, and the VP15TF and DP5010 PVD coated grades feature tough carbide substrates and proprietary crystal coating technology. For machining a wide range of materials, from alloy steels to various types of stainless steel and cast iron, the VP15TF grade ranges from 100-400 sfm, Griggs added. “The drill body is made resistant to corrosion and abrasion by using a superior high-heat resistance alloy and a special surface treatment suitable to counter new hard-to-machine work materials.”

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At Mitsubishi Materials U.S.A. Corp., Schaumburg, Illinois, the company’s DIAEDGE STAW indexable drills “are unique in that they have cutting edge geometry that is the same as the edge geometry on our DIAEDGE WSTAR solid-carbide drill,” said Barry Griggs, assistant business development manager of cutting tools. “The wave designed cutting edge and center point gash is aimed at improving machined hole accuracy.”

Both Sandvik and Kennametal will suggest the 45 degree cutter is a better bet for general purpose face-milling. The arguments given by these two for choosing the 45 are:

Be careful where you use 45 and 90 degree cutters. A workpiece that is not well supported, will deflect under a 45 degree cutter due to the high axial forces. A 90 degree cutter will produce a more consistent cut and the corresponding decrease in chatter will extend the life of the cutter.

The option of smaller diameter, high-feed end mills is “a popular option for harder tool and die steels, especially in the aerospace and mold industries,” Wilshire continued. “Customers tend to run the replaceable-tip drills and indexable end mills faster than their solid-carbide counterparts to shorten cycle times because the replacement costs are less and the time to index is shorter.”

I did do a couple of jazzy things.  First, I’m doing a 60 percent width pass.  This will give a better finish and go easier on the inserts in tough materials than a full width pass.  Second, I have specified this as an HSM cut.  That’s HSM for “High Speed Machining.”

“These screw-in heads are available from 8 mm up to 32 mm in diameter and can be mounted on extensions of various lengths,” he explained. “The smaller diameters have replaced solid-carbide tools in many instances. The advantages of both the replaceable-tip drills and modular, indexable end mills are similar: lower replacement costs, because instead of the entire tool being composed of carbide, only the portion actually doing the cutting contains carbide; less variability in position after indexing; the ability to easily change grades or geometries when cutting different workpiece materials; and less downtime when replacing worn tools.” However, he added, solid-carbide tools still provide better rigidity, deep-hole drilling and greater depth of cut capabilities when milling.

Carmex recently introduced new coatings for its Slim MT line. “This nano coating can handle temperatures 30 percent higher than TiAlN and is 25 percent harder than other coatings typically used for indexable cutters,” said White. “These coatings outperform others in high-temperature alloys like inconel and titanium.”