Steel, cast iron and aluminum are the workhorse metals most industries rely on. However, working in the aerospace, defense or medical industries often means working with difficult metals. These shops rely on hardened steel, titanium, heat-resistant nickel alloys and other materials that are notorious for the difficulties they present to machinists.

When working with exotic and difficult to machine metals, following correct practice is key. “Machining hard metals is a delicate process,” said David Moore, an applications engineer with Methods Machine Tools. “There’s a lot of room for error, machining takes more time, and you have to fine-tine every aspect of your process. When you’re dealing with expensive, exotic materials, preparation is critical.” We sat down with Moore, and others at Methods Machine Tools to discuss correct practices for working with difficult materials.

Cutting Tool Management
When cutting difficult materials, one of the most important considerations is the cutting tool itself. “Getting the tools to last is one of the biggest challenges,” says Ben Morone, another applications engineer from Methods. Harder metals can eat through the wrong inserts almost as quickly as you can replace them, and some materials warp and bend in ways that can keep heat trapped in the cutting tool.

Moore and Morone both emphasize how valuable it is to have the right coating. “Coating is very important, especially with harder materials.” says Moore. “If you use a standard coating on a carbide end mill, you’re going to burn through that quick. If you use the proper coating – with the proper speeds and feeds from your vendor – you’re going to be able to fly through the material, you won’t burn up your cutters, and you will hold to tolerance.”

Read more: Best Practices: Machining Difficult Materials