ISO P – Steel is the largest material group, ranging from unalloyed to high-alloyed material and including steel castings and ferritic and martensitic stainless steels. Machinability is usually good, but differs a lot depending on material hardness, carbon content, etc.
ISO M – Stainless steels are materials alloyed with a minimum of 12% chromium. Other alloys may include nickel and molybdenum. Different conditions, such as ferritic, martensitic, austenitic and austenitic-ferritic (duplex), create a large range of materials. A commonality among all these materials is that the cutting edges are exposed to a great deal of heat, notch wear and built-up edge.
ISO N – Non-ferrous metals are softer metals, such as aluminium, copper, brass etc. Aluminium with a Si-content of 13% is very abrasive. Generally, high cutting speeds and long tool life can be expected for inserts with sharp edges.
ISO K – Cast iron is, contrary to steel, a short-chipping type of material. Grey cast irons (GCI) and malleable cast irons (MCI) are quite easy to machine, while nodular cast irons (NCI), compact cast irons (CGI) and austempered cast irons (ADI) are more difficult. All cast irons contain SiC, which is very abrasive to the cutting edge.