TROUBLESHOOTING HOLEMAKING IN STAINLESS STEEL

Machining stainless steel comes with its own set of challenges. Here is an in-depth look at the entire process and the best methodologies

- Kruti Bharadva

Unlike machining other materials, machining stainless steel requires review of a myriad of aspects prior to beginning work in the machine shop. Not only should cutting tool specialists and coolant specialists be consulted, but machine capabilities should be addressed as well. Furthermore, one must verify that the correct tooling components are being used: cutting tool geometries, substrates, and coatings, type of coolant and coolant pressure among others. Still though, machining stainless comes with many unique challenges because of its low machinability—a machinability rating that needs to be overcome to utilize the many benefits of stainless steel.

STAINLESS STEEL FAMILIES

Stainless steel is offered in varying grades based on specific properties. These grades are also split into groupings based upon metallurgical qualities. Outlined below are the different families of stainless steel.

Austenitic – A rather common material, austenitic steel is identified as the Type 300 series; grades 304 and 316 are the most accessible. While austenitic stainless steel cannot be effectively heat treated, it can be hardened through cold working—the process of changing the shape without the use of heat. Corrosion resistance, low magnetism and good formability are also characteristics associated with this family of stainless.

Ferritic – As part of the Type 400 series, ferritic stainless steels are characterized by their corrosion resistance, strong ductility and magnetism and are typically iron-chromium alloys. This family can be altered through cold working rather than thermal hardening methods.