High Temp Tough

WIDIA´s new indexable milling grade is the first choice for titanium and other superalloys WS40PM´s cobalt-rich substrate provides robust fatigue resistance and edge integrity, while the multiphase AlTiN-TiN PVD coating reduces tool wear, making it the first choice for a wide range of high-temp steel alloys, austenitic and PH stainless steels, nickel-based super alloys such as Hastelloy and Nitronic, and titanium.

Josef Fellner, WIDIA Products Group´s Manager Portfolio Management for Turning and Indexable Milling, says the company recently took its newest advanced milling grade, WS40PM, on a world-wide testing tour. The results have been quite impressive:

 - An aircraft manufacturer enjoyed a 90% reduction in machining time per piece and increased tool life by 50% during Ti-6Al-4V face milling operations.

 - Insert flank wear decreased by more than 90% at a UK shop cutting Inconel 625, resulting in a 70% reduction in tooling costs.

 - At a turbocharger producer in China, tool life increased 80% while machining an austenitic stainless steel component using WS40PM, with improved part surface quality, reduced cutting forces and better chip flow.

 - In another titanium component, the WS40PM/VSM490-15 platform doubled metal removal rates and delivered 80% longer tool life through increased depth of cut and feed per tooth in face and shoulder milling operations.

 - The testing laboratory for a well-known brand of machine tools reports metal removal rates 49% greater when shoulder milling Ti-6Al-4V.

In each instance, WS40PM competed with the test subject´s legacy carbide grade. Speeds and feeds were kept the same or in some cases increased to take advantage of WS40PM´s exceptional toughness, wear-resistance, and ability to resist thermal cracking.

WS40PM was designed to meet the needs of the aerospace, defense, and medical industries, where titanium is used for everything from landing gear and seat tracks to lifesaving implants and surgical instruments. As the testing results show, however, WS40PM is suitable for far more than titanium. High-temp steel alloys, austenitic and PH stainless steels, nickel-based super alloys such as Hastelloy and Nitronic-these materials cause tool failure due to built-up edge (BUE), notching at the depth of cut line, cratering, chipping, and extreme heat generation, which in the case of wet-cutting operations leads to cracking.

“WS40PM´s advanced cobalt-rich substrate provides robust fatigue resistance and edge integrity, while the multiphase AlTiN-TiN PVD coating reduces wear,” says Mike Sperhake, EMEA-region Product Specialist for WIDIA. “Using an initial cutting speed of 175 ft/min (53 m/min) we´re seeing 25-35% productivity gains and consistent improvement in tool life, even when milling very tough materials like Ti-5553 and Super Duplex steels.”

Sperhake recommends a balanced approach to cutting parameter selection. “As radial engagement increases, cutting speeds should be reduced proportionately,” he says. “That´s because the amount of heat entering the insert goes up substantially on heavy cuts. At around 90% engagement, for instance, you´ll probably want to reduce the RPM by 25% or so, depending on the material. Feedrates may also have to be lessened somewhat, depending on setup and machine rigidity. And smaller cut widths, of course, spindle speed and feedrates should be kicked up substantially.”

“Going too easy” is a common mistake when machining titanium and other difficult materials, Sperhake says, leading to poor productivity levels and shortened tool life. For example, problems such as BUE and edge wear can often be eliminated by pushing the tool harder. “Tool life, especially in superalloys, is a three-legged stool of feed, speed, and cutter engagement. Each has a direct impact on the others.”

Success with superalloys takes more than a good carbide grade, however. Sperhake also recommends increasing the cutting fluid concentration, and using a high-pressure coolant pump wherever possible. Selecting the right cutter body for the application is likewise important. WIDIA´s VSM490 shoulder mill offers a state of the art insert and cutter design, one that supports WS40PM and other high-performance grades.

Finally, consider the machine tool, toolholder, and spindle interface. Rigidity across the board is needed for productive titanium machining. WIDIA offers the KM4X platform, which according to Global Product Manager Bill Redman is “the strongest connection available, period,” and is available on a wide variety of toolholders and machine tools alike.

Says Sperhake, “From Tier 1 aerospace suppliers to the job shop on the corner, everyone wants the same things from a tooling solution: higher accuracy, better surface finish, reliability and productivity. All are critical factors to their success, and that´s what we intend to deliver. WS40PM is a big part of that.”

WIDIA offers a variety of coolant-fed cutter bodies such as shell mills, shoulder cutters, end mills, and more, all able to accept WS40PM and other indexable milling insert grades.

WIDIA-brand products and services have defined innovation in the metalcutting industry for 90 years - from the world´s first patent for carbide indexable inserts to the development of the world´s first coated grades. The WIDIA brand offers a complete portfolio of precision-engineered products and custom solution services. With products for thousands of milling, turning, holemaking, and tooling systems, WIDIA is available through a worldwide network of authorized distributor partners who carry full-line solutions from a single source.

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For the latest WIDIA information, visit www.widia.com

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