KYOCERA SGS Precision Tools Group
KYOCERA SGS Precision Tools Group
Before talking grades and cutting data, it helps to put the decision in practical terms.
| What the Cut Needs | Cermet | Carbide |
|---|---|---|
High-quality steel finish | Strong fit | Strong fit |
Resistance to adhesion and built-up edge | Strong advantage in suitable steels | Depends heavily on grade, coating, and geometry |
High cutting speed | Strong in the right application | Broad capability |
Controlled interruption | Possible with the right grade and geometry | Generally more forgiving |
Milling | Available for selected applications | Broad application range |
Heavy impact or unstable cutting | More application-dependent | Usually the stronger starting point |
Scale removal | Avoid | Better choice |
Maximum application flexibility | More specialized | Broader capability |
If the only reason to consider cermet were purchase price, there would not be much of a technical story here. An insert that costs less but adds cost through longer cycle times, inconsistent tool life, poor finish, or scrapped parts is not saving the shop anything. The real reason cermet deserves consideration is that it behaves differently from cemented carbide.
That difference starts with what the material is made from. The name itself combines ceramic and metal. While conventional cemented carbide relies primarily on tungsten carbide, cermet primarily uses titanium-based carbides and nitrides. That different material base makes cermet less affected by the tungsten pricing pressure impacting carbide tooling, but the more important difference shows up at the cutting edge.
One of those differences is hot hardness. Cermet maintains greater hardness than cemented carbide as temperature rises, contributing to resistance against flank and crater wear and supporting higher cutting speeds in the right application. Another is its low chemical affinity with iron. Workpiece material is less likely to adhere to the cutting edge, reducing built-up edge and helping maintain a cleaner surface finish.
Put those characteristics together and cermet starts looking less like a lower-cost version of carbide and more like a cutting tool material with its own reasons for being in the holder.
This is where the “carbide by default” mindset can get in the way. A light finishing pass does not ask the cutting edge to do the same job as a heavy roughing cut, and a face mill taking a controlled finishing pass does not place the same demands on an insert as a cutter buried in an unstable roughing operation.
Cermet tends to be strongest when cutting loads are controlled and wear resistance, surface quality, adhesion resistance, or high-speed capability matter more than maximum edge toughness. That is why finishing has traditionally been cermet’s home turf. Smaller depths of cut, lower cutting loads, and higher cutting speeds line up particularly well with its material properties. But “good for finishing” should not quietly turn into “only for finishing.” Kyocera’s current cermet range spans high-speed finishing, general-purpose turning, unstable and interrupted turning, turning and milling, and grooving applications.
So instead of asking whether cermet is “as good as carbide,” the better machining question is which material actually matches the cut. If the application genuinely needs carbide’s toughness, use carbide. If it does not, paying carbide prices simply because carbide was already in the holder deserves another look.
A continuous steel finishing operation is still one of the most straightforward places to evaluate cermet because the cutting conditions play directly to its strengths. The chart shown here comes from an internal wear-resistance evaluation on 4137 steel, comparing PV720 with two competitor grades at 820 sfm, a 0.039-inch depth of cut, and 0.008 ipr, with coolant and CNMG432-type inserts.
PV720 showed less wear than both competitor grades at comparable cutting times and continued cutting beyond the time shown for either competitor. These results demonstrate strong wear resistance under the tested conditions, giving shops another reason to evaluate cermet in a properly matched application.
That is important because a lower-priced cutting tool material only creates value if the process remains productive. If switching inserts requires slowing the machine down or sacrificing tool life, finish, or dimensional control, the savings can disappear quickly.
Wear resistance is only one part of a successful tooling trial. Production machinists should also track part diameter growth and surface finish. As the edge wears, dimensional drift can force an offset adjustment long before the insert catastrophically fails. The chart measures wear over cutting time; a shop-floor trial should also confirm how long the edge maintains the required dimensions and finish.
That matters because tool life is not always just a question of “how long until the edge breaks?” Sometimes the better question is:
How long does that edge keep making a part you are willing to ship?
Cermet has long carried a reputation for being a poor fit for interrupted cuts, and for good reason: every time the edge enters and exits the material, fracture resistance becomes more important. But tougher modern grades have expanded what is possible. In a light-interrupted evaluation on 1045 steel with a single groove, PV730 with the PQ chipbreaker produced stable machining at 820 sfm and a 0.020-inch depth of cut, with wear resistance approaching the carbide comparison. Reducing feed from 0.006 to 0.004 ipr improved stability, while the PP chipbreaker remained an option at the lower feed when greater sharpness was needed.
The evaluation was then pushed further using 1045 steel with four grooves and more than 100,000 impacts. PV730 was still able to approach carbide-level fracture and wear resistance, but how the edge was loaded became increasingly important. Reducing feed toward 0.004 ipr improved stability, while increasing the corner radius to 3/64 inch provided another option that maintained stable machining without the same feed reduction.
The takeaway is not that interruption no longer matters. “Interrupted” by itself is simply not enough information to rule cermet out. Interruption severity, feed rate, edge geometry, setup stability, and required edge strength all matter. If changing the edge configuration can improve stability without sacrificing cycle time, cermet may remain a viable option even in interrupted work.
That means not every milling cut places the same demands on the edge. A face mill taking a controlled pass across steel is very different from a cutter buried in a heavy, unstable roughing cut. When cutting loads are controlled and the priorities are surface quality, resistance to adhesion, predictable wear, and productive cutting speed, cermet may be a viable option.
That makes selecting the right cermet grade especially important.
Cermet isn’t one cutting material with one set of characteristics. Each grade shifts the balance between speed, surface finish, wear resistance, and toughness. PV710 is built for high-speed finishing. PV720 balances wear resistance, toughness, and finish for general-purpose turning. PV730 moves toward fracture resistance for unstable and interrupted turning. TN610 extends the range into sharp, high-speed turning and milling, while tougher TN620(M) expands into turning, milling, and grooving. CCX uses CVD coating technology for maximum productivity in turning. As a rule, uncoated cermet favors sharp, clean cutting, while coated cermet is used to improve wear resistance and maintain surface finish over a longer tool life.
The grade is only half the decision. In turning, the PP chipbreaker emphasizes sharpness and low cutting forces for finishing, while PQ adds edge strength for finishing through medium cuts. A larger corner radius can support the edge in interrupted cuts, while feed changes the forces acting on it and can affect stability. In small-part work, feed can even determine whether the chipbreaker gets enough material to properly form and control the chip. In milling, the same logic applies to cutter engagement, insert geometry, lead angle, entry and exit conditions, and setup stability.
Choosing cermet isn’t as simple as swapping one word on a purchase order. The grade, geometry, coating, and application still have to match what the cut demands. It doesn’t eliminate process engineering. It rewards it.
Cermet options range from high-speed finishing grades to tougher choices for unstable cuts, milling, and grooving.
Download the Cermet Quick Guide for an at-a-glance comparison of PV710, PV720, PV730, TN610, TN620(M), and CCX by cutting speed, surface finish, toughness, coating technology, best use, and application.
None of this is an argument to empty the carbide drawer. There are plenty of operations where carbide’s toughness is exactly what the process needs. One particularly clear boundary is scale removal. Cermet is not recommended for removing scale, making carbide the better choice for that type of work.
Cermet is also more susceptible to thermal cracking than carbide because of its higher coefficient of thermal expansion and lower thermal conductivity. In interrupted cuts, running dry is generally the first choice. If coolant is necessary, it should be ample and consistent, since intermittent coolant can increase thermal cycling and make cracking worse.
The same logic applies to heavily loaded, severely unstable, or high-impact operations. Those cuts can demand a level of edge toughness that cermet is simply not intended to replace.
Small-part and Swiss-type machining provide another natural place to consider cermet because these applications often use smaller depths of cut and place a high value on part-to-part consistency. For these operations, SK is positioned as a general-purpose chipbreaker, while SKS places more emphasis on chip control at smaller depths of cut.
That becomes especially important when the cut is light enough that chip formation starts to break down. In that situation, the fix may run against a common instinct: If chip control becomes unstable at a very small depth of cut, increase the feed rate. Backing off can make the chip thinner, weaker, and harder to control, while a slightly heavier feed can give the chipbreaker enough material to properly form and break the chip.
That is a useful reminder well beyond cermet: Slower and lighter are not automatically safer.
Controlled evaluations tell us what a cutting material can do, but production applications tell us whether those advantages actually hold up on the shop floor.
Four documented user evaluations compared cermet with carbide in steel turning, and each showed a measurable improvement in tool life. In a 1045 hub ID application, PV720 increased tool life from 20 to 80 pieces per edge. An alloy-steel facing application improved from 200 to 420 pieces per edge, while a 1045 shaft OD application increased from 300 to 400. In another 1045 application, PV730 increased ring ID tool life from 120 to 165 pieces per edge.
The 4X improvement in the hub application is the number that immediately gets your attention, but the smaller gains may make the more important point. A shop does not need to quadruple tool life on every operation for an insert-material change to pay off. Even a more modest improvement can mean fewer insert changes, fewer index stops, less operator intervention, and lower carbide consumption when that gain is repeated across thousands of parts.
The important word is can. These are application-specific user evaluations, not a guarantee that cermet will deliver the same result in every machine, material, or setup. That is exactly why the better approach is to evaluate cermet one operation at a time and judge the result against the existing carbide process.
The lesson here is not to walk through the shop and start replacing every carbide insert that looks like a possible candidate. Start by asking why carbide is being used in the operation in the first place. Does the edge genuinely need carbide’s toughness and impact resistance, or is carbide there because it was the familiar, reliable choice when the job was originally developed?
A continuous steel finishing operation may be an obvious place to start. A controlled milling application where surface quality, adhesion resistance, and predictable wear are the real priorities may be another. Even a light-interrupted turning operation may be worth evaluating with a tougher cermet grade.
Before changing anything, establish what the current carbide process is actually delivering. Track parts per edge, tool life, cycle time, dimensional drift, surface finish, operator intervention, and most importantly, why the insert is ultimately being removed from the holder. Then evaluate the cermet application against that same baseline.
Do not judge the trial simply because the cermet edge looks different from the carbide insert you are used to seeing. Judge the process. If cermet delivers the required part quality and productivity while reducing tooling cost or carbide consumption, you’ve found an opportunity. If carbide still delivers the better process, keep carbide in the holder.
That is exactly what a good tooling trial is supposed to tell you.
Use the Cermet Quick Guide to compare grades, applications, and performance characteristics, or connect with a Kyocera distributor for application support.
A: Neither material is universally better. Carbide provides a broader application range and generally greater toughness. Cermet can provide advantages in suitable steel applications where surface finish, wear resistance, low adhesion, dimensional consistency, or higher cutting speeds are priorities.
The right choice depends on what the cutting edge actually needs to do.
A: Yes, in selected applications.
Tougher grades such as PV730 can handle controlled interruptions, but feed rate, chipbreaker, corner radius, interruption severity, and setup stability become increasingly important. In internal testing, reducing feed and increasing corner radius both improved stability under interrupted conditions.
A: Yes.
Kyocera’s TN610 and TN620(M) cermet grades are both positioned for milling as well as turning. TN620(M) also extends into grooving applications.
As with turning, the correct choice depends on cutting load, cutter engagement, workpiece material, geometry, and machine and setup stability.
A: Carbide is better suited for heavily loaded, unstable, or high-impact cuts where greater edge toughness is required. It is also recommended for scale removal, where cermet should be avoided.
A: No.
Insert price is only one part of tooling cost. Tool life, cycle time, parts per edge, dimensional stability, surface finish, insert changes, operator intervention, and scrap all affect the real economics of the process.
That is why the best place to start is not with a department-wide conversion.
Prove one cut.
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