Machining the wide range of steels

The ISO P material group is the largest within metal cutting. It covers steels ranging from unalloyed to high-alloyed material, including steel castings and ferritic and martensitic stainless steels. Although all steels are alloys in which iron is the major component, there are many kinds. For that reason, the specific machinability of steel for your application differs depending on material hardness, carbon content, alloying elements, heat treatment and manufacturing process (forged, rolled, cast, etc.).

In general, chip control of steel is relatively easy and smooth. Low-carbon steels produce longer chips that are sticky and require sharper cutting edges. The necessary cutting forces, and thus the power required to machine them, remain within a limited range.

The ISO P group is divided in two main categories:

• Unalloyed steels, which have a carbon content lower than 0.8% and are composed solely of iron (Fe), with no other alloying elements.
• Alloyed steels, which have a carbon content lower than 1.7% and contain alloying elements such as Ni, Cr, Mo, V and W. A distinction is made between low-alloyed steels (with <5% alloying elements) and high-alloyed steels (with >5% alloying elements).

Steels can be non-hardened or hardened, and tempered with a common hardness up to 400 HB. Steels with a higher hardness than this (from 48 HRC and up to 62–65 HRC) belong to the ISO H group.

Because of the generally good machinability and chip control of steel, and the wide range of different steel alloys, a variety of cutting tool coatings exist to help optimize the machining process and extend the tool's lifetime. Ionbond's engineers would be happy to discuss which coating offers the right balance of wear resistance, anti-sticking, sharp cutting edges and other desirable properties.