NTK Explains How Ceramic Tooling Cuts Aerospace Materials Up to 15X Faster

NTK Explains How Ceramic Tooling CutS Aerospace Materials Up to 15X Faster In a recent interview with MTDCNC, Peter Ward from NTK Cutting Tools tells us how ceramic cutting tools from the Japanese cutting tool manufacturer can drastically improve performance and productivity in the aerospace industry – machining at speeds and feeds up to 15 times faster than conventional carbide.

When asked by Giovanni Albanese why the industry should be turning to ceramic cutting tools, Peter explained: “The main reason to use ceramic tooling stems from its physical properties when compared to carbide. One of the key properties of ceramics is that they retain their hardness at high temperatures, which means we can use much higher and elevated cutting speeds than with carbide. If you talk about how much faster, you can be looking at 10 to 15 times faster. Where you may be turning Inconel at 50 to 100m/min with carbide, we have jobs running up to 500m/min with ceramic, making ceramic tooling use a transformational choice.”

With ceramic tooling set to save manufacturers hours rather than minutes on cycle times, MTD magazine asks why isn’t every manufacturer adopting this technology? “There are a few reasons, maybe education is the first reason. Secondly, some people may have had a bad experience in the past and thirdly, the application must be correct for ceramic tools. We can’t machine everything, and the machine tool and application also must be correct to successfully adopt ceramic tooling. This demonstrates that there are a number of factors that have to come together for manufacturers to really hit the productivity levels that we are talking about.”

Gio continued to ask Peter that if an aerospace manufacturer wanted to adopt ceramic tooling to improve processes, would it be a completely new process? Peter said: “Normally, yes. The way to successfully use ceramics means that you must change the programming styles, as they are completely different to carbide strategies. There are three or four rules that must be followed, but this is not complicated by any means. Ceramic tooling programming is by definition very simple as it is largely based around the second rule of ceramics and that is that they have a low breaking strength. So, all of your programming and all of your thinking has to be around avoiding shock loading.”

So, what are the rules for using ceramics? Peter informatively continues:” The rules to using ceramic tooling are all based around protecting the ceramic against shock loading. So, in the instance of turning a turbine ring, we would always want to prepare the part with pre-chamfering or ramping into the part to protect the insert. As a guide, only the first insert you use should be going into rough material; or the subsequent inserts should be working from the initial insert cuts. So, preparing the part is the first rule to consider.”

“The second factor to consider is the breaking strength. When roughing, we only use very strongly shaped inserts such as round inserts or secondly in the hierarchy would be square inserts with a large radius. The third rule is that we only really use rhomboid inserts such as CNMG and DNMG for small finishing cuts and clearing out corners.

When asked more about the educational process, changing the machining strategy and considering the inserts, Peter says: “This is not about replacing carbide with ceramics. You really do have to start from scratch, and as a supplier we must educate the customer as well. This is because there are things in addition to the programming strategies that need to be looked at, such as ensuring that part is suitable because we run so fast. Secondly, the part needs to be running in balance as out of balance parts are not so conducive to machining with ceramic. Additionally, we need to ask if the machine has enough power, gauge the coolant pressure and other factors.”

“When looking at the objectives of carbide tooling, manufacturers look to achieve high quality surface finishes, extended tool life and chip control. With ceramic tooling these factors are not the objective. The objective is all about metal removal.” Investigating the Suitable Grades “There are three material groups with around 10 different grades available. So, three material groups are Whisker ceramic, which is the oldest one that people will be familiar with as it has been around for a long time, especially in the aerospace industry. That consists of aluminium oxide with silicon carbide whiskers that make the insert stronger. These are very good for grooving, flank wear and some other operations. Then you have SiLon insert grades, these are tougher than other ceramic grades and can be used for milling, and then you have our brand-new composite material that is not even a ceramic, it is a completely new generation of materials – and this is the Bidemics range.”

“The Bidemics series is the one where you can apply very high cutting speeds, such as turning Inconel at up to 500m/min. This is a huge change in not only machining strategies but the resulting productivity gains. The Bidemics series can be transformational, taking hours from cycle times rather than moving from one carbide supplier to another in an exercise that may save minutes,” concludes Peter Ward.