It really depends on what is being cut. If you’re cutting a lightweight composite material, such as a CFRP (which stands for “carbon-fiber reinforced polymer”), you may need a diamond-coated carbide tool that can handle this oft-used in aerospace material.
Super hardened materials, categorized as H1 through H4 by Kennametal, for example, may need ceramic-based cutting tools that can mitigate the extreme wear resistance and abrasiveness of hardened H1 (up to 48 HRC) to H4 (greater than 60 HRC) materials.
At the end of the day, choosing the right tool typically comes down to what cutting tool material, geometry and coating is most effective at breaking the workpiece material’s metallurgical bonds while withstanding the heat and abrasiveness generated during machining.
If you’re new to figuring out metals, take a look at our article “A Cutting Tool Selection Guide: Ferrous Vs. Nonferrous.”
Are you burning through tools super quickly? Is part quality suffering? If you have a lot of experience machining lots of different materials, help each other out. Share your know-how.
One of the first things to consider when drilling stainless is the drill bit material. While it is possible to use high speed steel drill bits, cobalt is the recommended material to use for drilling stainless steel. Carbide is also a great choice but must be cost effective based on application before it can be justified. For example, carbide is generally recommended for production based application on CNC machines. Carbide would not necessarily be recommended for a 2 piece job done on a Bridgeport type mill. The most important thing to remember about working with stainless steel is that it can work harden relatively easy. Speed and feed parameters should result in a slightly faster feed and slower spindle speed than you might feel is normal. There are many charts available that give starting parameters. Pecking in stainless steel should be kept to a minimum to avoid work hardening. Generating as little heat as possible during the machining process is key to success in this material. Using plenty of lubrication, such as a dark cutting oil, will also help keep the heat down.