Mastering the challenges of hard turning

The Kennametal KBH10 is a new uncoated PcBN turning insert that is claimed to offer high wear resistance and very low cutting forces.

As a result, Kennametal says that many customers are now enjoying double the tool life together with improved part quality.
KBH10 PcBN hard-turning inserts are designed to turn hardened metals up to 65 HRc, especially where very high surface finishes are required. Typical parts set to benefit include bearing journals, rings and pistons, and gear hubs, where dimensional tolerances of <4 μm or less are increasingly common, along with surface requirements better than Ra <0.4 μm. In one example, a well-known automotive manufacturer was able to more than double tool life, from 150 to 350 pieces per edge during an internal facing operation on a 140 mm diameter 5115 alloy steel bearing hub that was previously heat-treated to 62 HRc. A drive-shaft producer achieved similar results, increasing tool life from 250 to 450 pieces per edge when turning 58 HRc UC1 (similar to S53) steel on its vertical turret lathes, consistently maintaining a surface finish of 6 Rz while doing so. In each instance, a cutting speed of 180 m/min was used, with depths of cut averaging 0.15 mm and feed rates ranging from 0.22 to 0.32 mm per rev. Also, in each case the customer saved thousands of dollars annually in insert costs compared with its existing solution, while substantially reducing downtime due to tool changeovers, says Kennametal. For further information