The three new ISO K geometries — MK5, RK5 and RK7 — featuring the Tiger.tec Silver high-performance cutting material from Bromsgrove-based Walter GB Ltd (www.walter-tools.com) provide greater process reliability and longer tool life in cast iron machining applications.

MK5, which is for medium machining and suitable for all cast iron workpieces, has an open chip-breaker groove for a soft cutting action and is targeted at applications in ductile cast iron, unstable components or internal machining with low cutting pressure.

The RK5 and RK7 geometries are for roughing. RK5, which is a classic flat-top insert without a chip groove, features a stepped plateau for optimum process reliability. RK5 is the first choice for grey cast iron, while RK7 is an extremely robust insert for very heavy interrupted cuts, very uneven material removal and hard cast skin; and while the RK7 geometry is similar to that of RK5, it has a protective chamfer on the cutting edge. RK7 is also suitable for the hard/soft machining of steels with hardness values of 40-61HRC.

A key feature of the new geometries is their plateau step between the location face and cutting edge, which allows the location face to be ground after coating (it is impossible to grind the location faces of standard CNMA and DNMA inserts without a chip-breaker groove); and while the uneven location face on standard inserts can lead to micro-vibrations and chipping at the cutting edge, the evenness of the face on these new geometries ensures that the indexable insert is securely seated for the highest levels of stability.

As a result, cutting-edge wear is reduced, particularly in the event of high dynamic loads. The inserts also feature an aluminium oxide coating with an optimised micro-structure, to extend the time it takes for crater wear recesses to form.

Tiger.tec Silver WKK10S and WKK20S cutting materials are used on grey cast iron, ductile cast iron and vermicular cast iron. WKK10S is primarily used for grey cast iron; it is also suitable for continuous cuts through to light interrupted cuts — and for use in dry machining. WKK20S is suitable for wet and dry machining, with ductile cast iron the primary application area.