When I’m walking the shop floor at our parts machining facility, I see cutting tools getting thrown in the chip bin every single day—some still look brand new, others are so worn you can barely make out their edges. It got me thinking a lot lately: so many of our clients, even the ones who’ve been working with us for years, sometimes ask, “Wait, what are the actual materials you use to cut my parts?” It’s a fair question, right? Because the tool material isn’t just a random detail—it’s what determines how fast we can machine, how accurate the parts stay, and even how much your order ends up costing. A lot of guys I work with on the floor just call them “carbide” or “high-speed steel” like it’s no big deal, but there’s more to each one than just the name. Let me break down what our team uses most often, why we pick each one, and when they work best for the parts you’re sending our way. Parts Machining
First up, the one we reach for more than any other: solid carbide, or just carbide around here. It’s not like the carbon steel stuff you might have a drill bit made from—this is a composite, right? Tungsten carbide particles pressed together with a binder, usually cobalt. The mix changes depending on what we’re cutting, too. If we’re dealing with tough, heat-resistant alloys that aerospace clients love to use, we go with a higher cobalt binder because it’s a bit more flexible and doesn’t chip as easy when we’re pushing hard. For softer, common materials like aluminum or even mild steel, we can drop the cobalt a little to make the cutting edges sharper—no need for extra toughness there, and the sharp edges mean a cleaner cut. I’ll be honest, though, carbide isn’t perfect. It gets brittle if it overheats, so if we’re running high-volume jobs that crank out a lot of heat (like machining stainless steel for food equipment parts), we’ll spray tons of coolant and even use coated carbide to make it last longer. Coating is another big piece I can’t skip here—we use things like TiN (titanium nitride) for general jobs, TiCN for harder materials, and even diamond coatings when we’re working with non-ferrous materials that tend to stick to regular tools. That diamond coating is game-changing for aluminum parts, by the way—no built-up edge, which means the parts come out smooth instead of having those ugly burrs you have to sand off later.
Next, high-speed steel (HSS). This is the old-school stuff, the kind your granddad might have used in a garage workshop, but don’t sleep on it. We don’t use it for most high-precision parts anymore, but when we’re making simple, low-tolerance parts or running a job that doesn’t need a ton of speed, HSS is way cheaper than carbide. Think of it like a workhorse for small jobs: it has more carbon than regular steel, so it can handle higher temperatures without dulling as fast. The grade we use most here is M2 HSS—it’s got a good balance of toughness and hardness, perfect for things like drill bits, end mills, or even taps for threading small bolts. The only downside with HSS is that it doesn’t hold up nearly as long as carbide. If we’re machining 1,000 aluminum parts, carbide might last through the whole run, but HSS would need two or three replacements. But if you’re ordering a prototype batch of 50 parts, HSS is totally fine—we can pass the lower tool cost on to you, which saves money on small runs. We also use powder metallurgy HSS for a few niche jobs; it’s made by compressing powdered steel instead of forging it, so the grain is more uniform and it’s a bit tougher than regular M2. That comes in handy when we’re doing slower, more delicate cuts on thin parts that can flex if the tool is too rigid.
Then there’s the one that sounds fancy but is actually super useful for specific jobs: cermets. I know, I know, cermet sounds like a sci-fi material, but it’s basically a mix of ceramic and metal—usually titanium carbide or titanium nitride mixed with nickel or molybdenum as a binder. We don’t use it every day, but when we do, it’s a huge upgrade for certain jobs. The big thing about cermet is it can cut way faster than carbide—like 20-30% faster—because it’s harder and holds a sharper edge way longer. The catch? It’s way more brittle than carbide, so it can’t handle any kind of interruption, like cutting a part that has holes or pockets in it where the tool has to stop and start. That means we only use cermet for continuous cuts on clean, uniform materials, most often stainless steel and cast iron. A lot of our automotive clients swear by cermet for their engine parts because the faster cuts mean lower lead times, which is huge when they’re waiting on parts to keep their assembly line moving. Just last month we did a run of 5,000 connecting rods with cermet end mills and the parts came out so smooth we barely had to do any secondary finishing. That’s the kind of win that makes even the shop foreman happy.
Let’s not forget ceramics either—wait, not the dishes in your kitchen, but ceramic cutting tools. These are made from aluminum oxide or silicon nitride, and they’re basically unbreakable when it comes to heat. They can handle temperatures up to 2,000 degrees Fahrenheit, which is way hotter than any machining job we do, so they’re perfect for super hard materials like hardened steel, Inconel, or other aerospace superalloys. The only problem is, they’re so brittle we can’t use them on anything that has irregular shapes or requires any kind of interrupted cut. We use ceramic tools mostly for finish cuts on parts that need to be super tough—like turbine blades for jet engines, which have to hold up to extreme heat and pressure. I remember a few years back we tried using carbide on a run of turbine blades and half the tools wore out before we finished a third of the batch; switching to ceramic cutters cut our tooling time by 70% and got the parts out two weeks faster. It’s a specialized tool, yeah, but when you’re working with materials that are almost impossible to machine with regular tools, ceramics are the only way to go.
Oh, and there’s diamond—polycrystalline diamond (PCD) to be exact. That’s the hardest material on Earth, so obviously we use it for super soft, non-ferrous materials that would wreck regular tools. Think aluminum, copper, brass, even graphite. Graphite is weird because it’s super abrasive, so regular carbide tools dull in minutes, but PCD? It lasts through hundreds of parts. We also use PCD for finishing cuts on things like copper electrical components, where the surface has to be absolutely smooth to conduct electricity well. The downside? PCD is expensive—way more than carbide or HSS—and it only works on non-ferrous materials. If you try to use it on steel, it just eats the diamond away, so we stick to it for the jobs where it actually makes sense. We recently did a run of 10,000 copper heat sinks for a tech company, and using PCD tools meant we didn’t have to replace tools once during the entire run. That’s the kind of reliability that makes our clients come back, right?
Wait, I should also mention coated tools, because that’s not a material but it’s just as important. A lot of people think the material is the only thing that matters, but the coating is what makes the tool last. We use coatings like TiAlN (titanium aluminum nitride) for high-heat jobs, like machining titanium, because it resists oxidation way better than TiN. For aluminum parts, we use diamond coatings as I said before, and for threading jobs, we use TiCN because it’s less likely to stick to the material. The coating is super thin, only a few microns thick, but it reduces friction between the tool and the part, keeps heat down, and prevents the material from building up on the tool’s edge. I’ve seen guys skip the coating to save a few bucks on tooling, and they end up having to redo half the parts because of burrs or rough surfaces—total false economy.
Now, let me talk about how we pick the right tool for your part, because that’s where a lot of machining shops drop the ball. It’s not just about grabbing the hardest tool or the cheapest one—It’s matching the tool material to your part material, the tolerance you need, and how many parts you’re ordering. If you’re sending a prototype of a plastic bracket, we’ll use HSS because it’s cheap and works fine for low volume. If you’re sending a high-volume run of stainless steel medical parts with tight tolerances, we’ll use coated carbide to keep the cuts accurate. If you’re machining a turbine blade made of Inconel? We’ll go with ceramic tools, no exceptions. We also factor in lead time—if you need the parts in 3 days, we might use a cermet tool to run faster instead of waiting for a special carbide tool to come in.
I know a lot of small business owners or engineers might not think about cutting tool materials when they’re sending a quote request, but it makes a huge difference in your final part. Last year, a client sent us a quote for a run of 2,000 aluminum parts and wanted the lowest price possible. We quoted HSS tools, but when we ran the numbers, we saw that using PCD tools would only add $0.20 per part, but it would eliminate all the burring work they had to do in-house. They ended up going with the PCD tools and saved $1,500 in finishing costs. That’s the kind of value we try to bring to every job, not just the big corporate accounts.
At the end of the day, cutting tools are the unsung heroes of parts machining. They don’t get talked about as much as the CNC machines or the part designs, but they’re the reason we can turn a solid block of metal into a precise, functional part that fits perfectly into whatever it’s going into. Whether you’re ordering a prototype or a 10,000-part run, the material we use for the tool is something we always think through, because it affects every part of the process—from the speed we run at to the quality of your final part.
If you’re working on a project right now, whether it’s a small prototype or a big production run, and you’re wondering what tool material will work best, or you just want to chat through the best way to get your parts machined right, feel free to reach out. We’re here to walk through your needs, pick the right tools for the job, and make sure your parts come out exactly how you want them. Don’t hesitate to connect with our team to discuss your next order—we’re ready to help.
Stud&Bolt References:
- Tonshof, H. K., et al. "Advanced Cutting Tools in Machining." CIRP Annals, vol. 49, no. 2, 2000, pp. 561-574.
- Byrne, G., et al. "Cutting Tool Materials and Their Performance in Machining Processes." Journal of Materials Processing Technology, vol. 134, no. 1, 2003, pp. 77-86.
- Childs, T. H. C., et al. Metal Cutting: Theory and Applications. Butterworth-Heinemann, 2017.
Kunshan Haizhijie Precision Hardware Co., Ltd.
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