A look at ultra-precision grinding for micro tool manufacturing - Engineering.com

Oct 16, 2024

3D Printing

Micro tools play a critical role in the manufacturing of medical devices, microelectronics, semiconductors, and any miniature component where precision is essential. Darren Fox, a product manager at ANCA with over 33 years of experience in the cutting tool industry, discusses ultra-precision grinding and ANCA’s FX7 Ultra in this podcast. Scroll down to read a recap of the conversation.

With precision grinding, we looked at the micron features of a cutting tool. But now, with ultra-precision grinding, we look at the sub-micron features. Achieving the perfect cutting tool requires a lot of detailed attention, not just in the machine but also in the software — things that directly affect tool geometry, tolerances, profile accuracies, surface finishes, cutting-edge qualities, and even transition marks between axis movements. Then, controlling everything with a combination of machine and software, we have LaserUltra, MTC, tool runout compensation, and a few other things we’ll get into later.

Over the years, cutting tools have continued to evolve with customers’ demand for that extra edge over their competitors. They’re chasing higher-quality surface finishes and more high-performance tools to remove material quicker while maintaining the accuracy of their parts and looking for longer tool life. All of this impacts the cycle time, reduces machining costs, and increases productivity.

To produce these types of tools, the grinding machine must also evolve within its own technologies. It’s a constant challenge, which we love here at ANCA, and it requires a high level of R&D, which is made possible using vertical alignment.

What I mean by vertical alignment is that we can control everything we do. We do all our own engineering in-house; we do our own servo drives, controls, and linear motors. And we can control everything we do and develop at speed or pull back development to suit what we need at the time.

So, the new level of precision we’re seeing now in the Ultra machines is driven by market demand and the need for higher-quality cutting tools.

We can do micro tools, and it’s very good at it. With the development of the Ultra program and the FX7 Ultra, customers can expect high-quality tools for all their tools manufactured across the Ultra range, regardless of size. So, with the FX7 Ultra, we can do tools from up to 20 mm in diameter, and you can expect to receive these ultra-quality tools on the large tools as well.

However, during those advancements, we’ve enabled the grinding of small tools and micro tools down to 0.1 mm, or 4,000ths of an inch, which is now redefining standards presently set within that small and micro tool market.

General cutting tools are made from a few different types of materials, depending on the application. High-speed steel, carbide, ceramics, and PCD are all used in the cutting tool world. However, carbide has a big percentage of these tools and is generally used.

With micro tools and tools down to 4,000ths of an inch, we generally use a sub-micro grade of carbide because of improved hardness and edge retention. On a tool that small, where we need high surface speed, we need to hold a high-quality cutting edge, and sub-micron carbide generally does that for us.

One of the main features that separates the ultra-machines from a standard machine is our one-nanometer control. This gives us control of the axes down to a one-nanometer resolution. That’s 1,000,000th of a millimeter resolution or control over our axes, which ensures a silky smooth movement of the axis and a smoother surface finish. This level of resolution of the one-nanometer control is the first of its kind in the tool and grinding machine market. So, it’s a really exciting thing for us.

Another feature we have on the FX7 Ultra is MTC, which is motor temperature control. Many factors can influence the grinding spindle growth. For example, high rpm versus low rpm load on the spindle. So, we might be doing a heavy fluid cycle or a finishing cycle, and the different loads can put different temperatures through the spindle, resulting in spindle growth. MTC actively manages and maintains the temperature of the motor spindles, meaning faster warm-up times, production can start a lot earlier, thermal expansion is reduced, and, in turn, you maintain consistency across your batch of tools.

We also have new servo-controlled algorithms, which give us faster response times to internal and external disturbances.

LaserUltra is another feature on the machine used for in-process compensation. The laser measures the tool after we’ve ground it, checks the detail or dimensions against what we say we should be getting, and compensates accordingly to make your next tool perfect. That gives us consistency from our first to our last tool across a batch.

Also, with the FX7 Ultra, we’ve got a new C-axis design, which gives us greater stiffness and rigidity and many other features that are probably smaller detail but all make up the Ultra machine and make it possible to grind these high-quality tools, especially down to the micro level.

Software plays a critical role. Without the software, it’s impossible to design some of the cutting tools required on the market. When we looked at the sub-micron level features of a cutting tool, we looked at where we needed to improve ourselves and added some new features. We now have a designer edge bullnose software, new chisel edge geometries — be it linear, circular, or line segment chisel edges — new circular segment cutters, variable pitch variable helix type cutters. And this has all been designed by ANCA itself.

Once again, mentioning our vertical alignment, we do everything internally ourselves. We write our own software and make our own controls. And we develop that how we need to depending on the market.

We also introduced tool balancing software, which minimizes any out-of-balance effect on a tool when used at high speeds so we can ensure it is perfectly balanced.

Tool run-out compensation eliminates any errors through inconsistencies in your cut where you might get small runout. With tool runout compensation, we can digitize a tool, find where that runout is, and adjust the grinding path to ensure less than two microns runout for your cutting tool.

All of this is possible first-up when we use our 3D software simulation. This gives you the confidence to play around and make mistakes on the simulator before you grind. So, you know that when you go for your first tool, it will be as close to perfect as possible.

We are looking at different levels of AI at the moment. The new servo-controlled algorithms that I mentioned before, which are a part of the machine or the development of the Ultra, are self-learning. It quickly reacts and learns what it needs to internal and external disturbances.

AI will play a big part in machines moving forward. Where it takes us is still unknown, but it’s moving forward and definitely part of the future.

I wish I had a crystal ball. The development of the Ultra is still relatively new, so there’s still a lot of development within the Ultra range. But given its capabilities today, we see AI playing a fair role within the machines in the future. We’ve also got R&D teams looking at the next thing within grinding machines. Is it grinding? Laser ablation? 3D printing?

Who knows what the future holds? But we have teams and a network of subsidiaries that we work alongside to ensure that we drive our machine forward. So, it’s really exciting times, with what we’ve done and what we can see in the future.

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