It has taken a while — more than 30 years by one account — but high-feed-rate end mills are being developed that meet the performance capabilities of evolving machining systems and their controls.
So says Juan Seculi, global product manager of indexable milling products at Kennametal, based in Latrobe, Penn., in discussing the benefits of two recently developed families of insert end mills for high-feed operations.
The products are from Widia, a German company owned by Kennametal, whose tools are marketed as a separate brand. The newest family of end mills is the M370 Series for roughing and finishing large (15.75- by 12- by 15.75-in workpiece) and medium-sized cast iron and soft-steel components on 3- to 5-axis machining centers. The other end-mill family is the M270HF (High-Feed) Series for roughing and semi-finishing small and medium components with complex geometries.
The new tools complement ongoing advances in machining speed, as well as the capability of CNC systems to operate with more cutting data, according to Seculi in telephone and e-mail interviews from Kennametal Shared Services in Germany. “These developments let us put tools in machines that operate much faster than conventional tools,” he says. The idea behind high-feed-rate machining tools goes back to at least the 1970s, “but it’s only since the end of the 1990s,” Seculi says, “that high-feed tools have been developed and applied thanks to new [performance] technology used by machining centers and CAD/CAM systems.”
Widia’s high-feed-rate designs entail a relatively small depth of cut at a high fz (starting feed) value. The company says this results in high material removal rates (MRR) and greater productivity at low radial force.
M270HF end mills are based on Widia-Hanita X-Feed geometry, which Seculi describes as “a specific solution/platform launched by our [end mill] brand Hanita a couple of years back. We have brought that geometry/concept into the M270 platform to allow it to be applied in high-feed applications.”
The tools have a precision ball nose that accepts toroidal inserts and the company’s new high-feed inserts, as well as V-shaped contact faces for rigidity and cutting accuracy. They have carbide shanks.
The M270HF series comes in three grades: TN2505 for wear resistance in working with materials with up to 60 HRc hardness, TN6540 for greater toughness and TN6525, which combines toughness and wear resistance when used to dry-machine steel.
M370 end mills are double-sided components with up to six cutting edges per insert. Widia says this configuration combines high MRR and an efficient operational cost per cutting edge. The mills feature two insert geometries: MH (Milling Heavy), which is made of P6 steel and is for high-feed roughing of steel and cast iron, and MM (Milling Medium), which is made of P5 high-alloy steel and exerts a lower cutting force when finishing soft steels and stainless steel.
Widia says that the six cutting edges per insert of the M370 end mill can provide 25 percent longer tool life than conventional tools with three cutting edges.
The M270HF end mills come in sizes ranging from 0.375 to 0.75 in, while the M370 tools are available in 1- to 3-in sizes. Through-tool cooling is optional on the M270HF and standard on the M370.