Machining nickel-based high-temp alloys

Perhaps the most basic assumption in machining is that cutting highstrength materials takes higherstrength tools. Proprietary nickel-based alloys used in gas and steam turbines, for example, are among the world’s strongest materials, continually being developed to allow power plants to run at much higher temperatures. This not only provides more power to those that need it, it increases plant efficiency and reduces or eliminates harmful emissions. Superalloys such as Inconel, Waspaloy, Rene, and others come into play in turbine blades and other parts that require high strength, excellent high temperature creep resistance, phase stability, and resistance to oxidation and corrosion.

But machining such materials can be a slow, laborious, and cost-intensive experience. In general, solid carbide tooling commonly runs at speeds between 65 and 200 SFM (20 to 60m/min) in such materials with limited tool life. New Beyond KYS40?-grade solid ceramic endmills from Kennametal, however, are presenting orders-of-magnitude improvements in machining high-strength nickel-based alloys, roughing at cutting speeds up to 3,300 SFM (1000m/min) with tool life two to three times longer than comparable solid-carbide tools.

Industry first
Cutting tools made of ceramics, mainly aluminium oxide (Al2 O3) have existed since the early 20th Century. Patents on ceramic cutting tools were issued in Germany in 1913 and were commercially available in the U.S. in the 1950s. Ceramic indexable inserts have their place today because they can operate at higher speeds in selected applications, but solid ceramic end mills were rarely seen because such tools were more brittle than carbide and did not perform well. In fact, many turbine manufacturers have taken to producing their own solid carbide end mills in house due to the high consumption of these tools.

Kennametal’s new SiAlON KYS40 ceramic grade and the overall design of the solid ceramic endmill now offers the most effective way to rough nickel-based hightemperature alloys. “Cutting speeds on nickel-based superalloys can be up to 20 times higher compared to solid carbide end mills, and due to ceramic’s outstanding heat resistance and stronger cutting edges (negative rake), tool life can last five times longer or more,” says Thilo Mueller, global product manager at Kennametal.

Two types of KYS40 solid ceramic end mills are available, a six-fluted version for face milling and profiling; and a four-fluted, necked version for slot milling and pocketing. Both product lines allow ramping, helical interpolation, and trochoidal machining strategies as well.

The wear mechanisms and wear indication on the solid ceramic end mills is completely different from carbide, allowing running ceramic end mills far beyond the point where carbide tooling would need to be replaced. That’s also the reason that this new KYS40 grade end mill is a throw-away type of tooling to allow usage beyond regular type of wear.

Turbine blade machining
Whether powered by fossil fuels, hydro, or nuclear power, almost all electrical power on earth is generated by a turbine of some type. Producing, managing, and maintaining these critical components are vital to keeping the power flowing.

This puts a lot of pressure on manufacturers to continually update their machining strategies. Many factors affect this: are large numbers of similar blaAir Max 90 NS GPX Mid