ISO - S :

Heat-Resistant Super Alloys include a great number of high-alloyed iron, nickel, cobalt and titanium based materials. They are sticky, create built-up edge, harden during working (work hardening), and generate heat. They are very similar to the ISO M area but are much more difficult to cut, and reduce the tool life of the insert edges. Heat-resistant “super alloys” based on iron, nickel or cobalt as well as titanium alloys are included in group S. It is divided into the application groups 01-30, dependent on the cutting load.

ISO - H :

This group includes steels with a hardness between 45-65 HRc, and also chilled cast iron around 400-600 HB. The hardness makes them all difficult to machine. The materials generate heat during cutting and are very abrasive for the cutting edge. This group includes hard machining of hardened steels. The application groups are from 01-30, depending on the cutting load.