Sumitomo Turning Grade Provides Long Tool Life in Cast Iron Applications

Sumitomo has developed its AC4125K turning grade to lower overall tool usage and tool-change frequency while providing stable, long tool life in cast iron applications in the automotive industry, among others. Gray cast iron is used for parts like engine blocks and brake discs where sliding is required, while ductile cast iron is used for parts such as differential cases and carrier cases where strength is required. Gray cast iron is an alloy primarily composed of carbon and silicon. Gray cast iron appears gray on the fracture surface because carbon is more present in the form of graphite than in the form of cementite. Ductile cast iron contains somewhat more carbon and silicon than gray iron, with the graphite becoming spherical due to the addition of magnesium and/or cerium.

AC4125K is said to be Sumitomo’s first recommended grade for interrupted machining of cast iron. Through the use of Absotech Coating, a chemical vapor deposition (CVD) coating technology, the turning grade provides optimal chipping resistance by maximizing compressive stress to achieve stable and longer tool life for roughing of components such as differential cases and carrier cases. The gold color of the inserts makes it easy to identify used corners, assisting in the improvement of tool management.