Working with hardened steel can be brutal on your tools. CNC End Mills for High TemperatureIt is important to choose the right cutting and forming tools that will hold up, provide clean cuts and continue to perform over and over again.

Using the right indexable end mills not only gives you increased precision, but it can also lead to longer lasting tools. An appropriate coating is crucial to performance. Certain materials are better for metals versus non-metals, ferrous versus non-ferrous or hardened versus soft metals.

Crystalline Diamond Coating

An end mill with a crystalline diamond coating is formed using a carbide substrate. The crystalline diamond structure greatly improves hardness, leading to increased resistance to abrasion. It is a thick, multi-layer coating that can withstand temperatures up to 1100°F. End Mills for Hardened Steel Use AITinIt is most suitable for non-ferrous metals and ceramics. The lower temperature threshold makes it ill-suited to hardened steel.

Titanium Nitride

TiN is the basic coating used on cutting tools designed for soft ferrous metals. It is a general-purpose ceramic material that strengthens the base metal of CNC end mills. Titanium Nitride is applied in a thin, single-layer coating and can withstand temperatures up to 1000°F. The material is hard and conforms to the substrate, but it is not sufficient for hardened steel cutting.

Aluminum Titanium Nitride

AlTiN takes the strength of TiN a step further. This coating is a high-performance material that improves end mill performance when used on ferrous metals, such as titanium, nickel, alloy steels and stainless steels. The substance is a crystalline structure constructed from bonds between AlN and TiN molecules.

AITin Can Handle the Heat

AlTin is a harder substance than TiN, carbide and chrome. It can withstand temperatures up to 1450°F and performs best in high-temperature settings. The high heat is what creates the aluminum oxide layer. This reduces thermal conductivity in the end mill and, instead, transfers the heat to the cutting. The coating maintains its hardness even at elevated temperatures.


Rather than a single layer, aluminum titanium nitride is applied as a multi-layered coating. The material is non-porous and adheres well to the tooling substrate. It produces a clean, sharp and long-lasting edge. Additionally, AlTiN is durable, creating a strong bond with the end mill material that won’t easily flake off or chip, leading to tools that last up to three times longer than those that are not coated.

End Mills for Hardened Steel Made by Garr Tools

Endmills for Hard Metals

Garr Tools has a vast catalog of tooling options. Above are some of the end mills that we have found perform well when working with titanium and many of the super alloys like Iconel and Hastalloy. If you have a project that requires an end mill or cutting tool that performs well with hardened metals, give Judy a shout and she can share her insights and get you the right tool for the job.

Call Judy here: (888) 235-9950 or complete the form on our contact us page.

Colburn Supply is an industrial supply company in PA with a focus on metalworking tools, milling machine fluids and abrasive products.