What is PCD?

Face Mill:
DM90.R063.14.05.2A PD45

Exchangeable Head Endmill:
Head:
DG10.C10.01.2.05.2A PD70
Shank:
MG10.HA12.100.1

Endmill:
DM25.C06.01.3.08.0F PD45

Helical Mill:
DM33.V16.30.130.1A PD42

Daniel
Today we're going to learn about one of the most powerful advancements in modern machining: polycrystalline diamond. We're going to cover the basics of PCD, when, and what to use it, and give you some practical tips on how to achieve maximum performance with every tool, every time. Let's go talk to Eddie, our Horn Academy Training Manager, to learn more.

Daniel
What are PCD tools?

Eddie
So PCD stands for Polycrystalline Diamond. So it's a synthetic diamond material. PCD tools are north of 6000 Vickers hardness. So it's a much harder tool. It's also very highly engineered, So there's polished rake faces and surfaces, laser geometry. So the edge prep is precision ground. It's a very engineered product. And much more so than carbide.

Daniel
And for my understanding, MCD, monocrystalline diamond is a single diamond grain. Where as polycrystalline diamond is multiple fuzed together with cobalt. Is that correct?

Eddie
Yeah. That's correct. Cobalt and other elements. Sometimes you have nickel. Or other composite ingredients that, that give it some heat. Resistance or create a harder bind to the material.

Daniel
And I think from varying the grain size, whether it's a larger grain for more durability or a smaller grain for more surface finish, you can achieve, different properties, even though it is all within PCD. Is that correct?

Eddie
That's correct. Larger grain size means higher toughness. So if you have, interruptions in your cut or an unstable process of some kind. Then the larger grain products can give you a little bit better resistance to chipping. If you have the smaller grain, it's going to resist the edge chip out. And we're talking about a microscopic level edge chip out and longer tool life and surface finish, because the surface finish comes from the edge eroding away. So as your edge erodes, so does your surface.

Daniel
Tell me a little more about the benefits of PCD.

Eddie
You have edge sharpness much longer than you would with a carbide tool. Because the substrate hardness is so much harder, you can maintain that edge acuity that you need for non-ferrous machining. You're typically using this in a high production environment. This really, is not directed at a job shop where you're running 1 or 2 parts. This is where you're running thousands of parts and you need it to perform in a consistent way. So you have predictable tool life and predictable stoppage of the process. So aerospace, automotive are heavy users of PCD tooling. When you're running large scale aerospace parts or automotive. You need consistent tool life. You can't have machine stoppages at unpredicted times, and you need to minimize those stoppages because typically it's a transfer line where they're running millions of parts, so you need something with long tool life.

Daniel
PCD has really high thermal conductivity, but at the same time very low friction. So how does that contribute to better cutting?

Eddie
Well, the worst thing that can happen in aluminum is when you have material adhere to your cutting edge. Aluminum, or really, non-ferrous materials, they require a very sharp cutting edge to work correctly. And when you dull the edge with material adhesion, you create a lot of unnecessary heat and force pressure on the cutting edge, which can lead to shorter tool life.

Daniel
And I've heard that with these tools, since it is a synthetic diamond. If you use this in a ferrous application, when the tool heats up, the carbon in the diamond, chemically reacts with the iron and degrades the edge. So is that why you would never want to use this in a ferrous alloy or something like titanium even?

Eddie
Yes. That's correct. The iron can leach the carbon out of the material, and shorten the tool life dramatically. So typically, you would not use it on, iron based materials. Second, the cost of the tool compared to carbide, you need to get the cutting speed out of it. When you're machining non-ferrous, you're running really high cutting speeds, so it makes sense. But if you're using an on an iron material, you can't run at the kind of elevated speeds that you would see, with a non-ferrous alloy. So you kind of lose the economy of using PCD. So it makes way more sense for non-ferrous than it does for iron materials.

Daniel
I've heard that PCD tools are also great in, very abrasive materials. Can you tell me more about that?

Eddie
Yes, if you have an abrasive plastic, or carbon fiber, or even aluminum that has high silica content, normal carbide tools will not resist that abrasion. They wear down very, very fast. Because this material is on a scale three times harder, can maintain the edge, consistency. You're much better off. If I'm machining a carbon fiber, for instance. I can't afford for the edge acuity to be, diminished really quickly because I'm going to start pulling out fibers and have bad components. So having a sharp edge for a longer period of time, even in, with the abrasive material, is critical for aerospace and automotive customers.

Daniel
And then in terms of cutting forces, because the edges can remain sharp for so long, does that mean that thin wall features are a lot more feasible with PCD tools?

Eddie
Yeah, absolutely. As your tool edge wears on a carbide tool. It's going to start pushing around thin walls in a, in a bad way. So maintaining that edge acuity throughout the process is, is highly important. Which is why aerospace companies turn to PCD for solutions.

Daniel
And looking at the parameters that you're going to be running PCD at, what are some of the considerations that users need to take into account?

Eddie
As I always say, look at the MRR rate. The cost per cubic inch for your tool, compared to a carbide solution, and see if that makes sense. You will need to do calculations to figure out the max RPM for your machine. Typically with smaller tools, you're going to be at that max RPM. With the larger diameter tools, they're a little bit more forgiving. You can see in the background the DM90 running. We're able to do that because the diameter is so big. We're able to achieve a very high cutting speed. So you need to consider that your tool needs to run high speed to be economical.

Daniel
And even though PCD has a lot of very strong benefits, what are some of the cases where carbide would be a better alternative.

Eddie
If your, your machine is not very rigid. The system fixturing no good. You're not going to make use of the higher speeds, because you're going to have a lot of vibration in the process and vibration at, at high rate is just going to cause chipping in and problems with the tool. And then if your RPM is very limited, you're also going to limit your productivity with this tool. The feed ranges for these tools and the depths of cut are going to be very typical for a carbide tool. You cannot exceed the volume of material in the chip flute with the speed. So you want to make use of the cutting speed, the high cutting speed to get your productivity.

Daniel
All right. So since we've covered some more of the characteristics and the use cases for PCD, let's look at a couple of the tools that we've used for a demo here, starting with the DM25. This tool seems best for profiling, but has other applications too.

Eddie
Well, if you look at the sample part we've made here,

Eddie
this tool is, is producing the internal pocket here, and you can look and see the finish is very high finish. Your depth of cut is in the range of the PCD chip. So you can go into a part from solid, and also profile inside a component.

Daniel
And then next the DM30 is more like a traditional end mill style, with multiple flutes. And it seems like it's pretty good for, single pass finishing.

Eddie
Yeah. This is, a very highly engineered tool. So all of the cutting edges are held in micron tolerance of one another. So you can take very large depths and take, different steps. And those, those steps will be very fine. Very clean wall even though multiple depths might be taken.

Daniel
And then next the DM33, its main application is pocketing and, it can remove quite a bit of material.

Eddie
Yeah, you can see this tool was used. We're profiling out the inside of the part. We're removing most of the volume in a helical boring operation, with that tool. So also, very high ramp angles for the DM33.

Daniel
And I guess another additional benefit is that you can run this with a long stick out to be able to, pocket very deep features.

Eddie
Yes.

Daniel
And then next we have the DG series. We ran both a, a 90 degree cutter and a ball nose and Eddie I think the benefit for this series is its versatility. Is that correct?

Eddie
Yeah. With the DG, what you're not paying for is the additional carbide in the back. Even though this is a carbide shank, it's much more economical to produce in this form. So with the head instead of, using a re-grinding service or re-lapping service. You can change these heads out and put a new one on. Because it's very highly engineered, you're going to get very high repeatability with that tool. So the functional end of the tool that you're using is down here, so you're not paying for a lot of tool that you're not using. So the DG system is a very good system for that. Long reach into the part. Without the expense of a lot of grinding on the, on the tool. So you're paying for what you're. Using on the end rather than an entire tool.

Daniel
That makes a lot of sense. And in addition to these standard products, we also offer, special or custom tools. Is that correct?

Eddie
Yes that's correct. So any kind of, special form tool. Drilling counter, sinking tools, really the sky's the limit. As you know, Horn produces a lot of custom solutions across all manner of types of machining, and PCD is no different.

Daniel
And what's the best way to get started with PCD tools? If you've never used a system like this before?

Eddie
I'd say the first step in PCD is educate yourself on the parameters. Talk to your cutting tool supplier. Figure out your application. If it's the right choice, a cutting tool supplier should not try to sell you PCD if it's not the right solution, but just educate yourself on that. There's all kinds of resources. On the Horn website. You can look and ask one of our technical specialists, and they'll help you make the right decision.

Daniel
I hope you enjoyed the short overview of PCD. If you'd like to take advantage of this exciting technology in your shop, Horn USA is here to assist American manufacturers tackle unique machining challenges with confidence. If you'd like to learn more, please reach out to your local Horn sales rep for us to assist you. And remember if you enjoyed this video or got anything out of it, please like and subscribe and we'll see you in the next one.