Tool coating can be divided into the following categories:
(1) Titanium Nitride Coating (TiN)
TiN coating is a universal type PVD coating that can increases tool hardness with high oxidizing temperature. When used on high-speed steel cutting tools or forming tools, TiN coating can help tools get very good machining effect.
(2) Titanium Nitride Coating (TiCN)
The carbon in the TiCN coating can increase tool hardness and achieve better surface lubricity. So the TiCN coating is an ideal coating for high speed steel tools.
(3) Nitrogen Aluminum Titanium or Nitrogen Titanium Aluminum (TiAlN / AlTiN)
The aluminum oxide layer formed in the TiAlN / AlTiN coating can effectively increase the high temperature processing life of tool. The coating is mainly used on hard alloy cutting tools for dry or semi-dry machining. Due to the ratio of aluminum to titanium of the coating, AlTiN coatings provide a higher surface hardness than TiAlN coatings, which makes it another viable coating option for high-speed processing.
(4) Chromium Nitride Coating (CrN)
The good anti-caking property of the CrN coating makes it the first choice coating of machining that easy to form built-up edge. With this almost invisible coating, the processability of high-speed steel tools, carbide tools and forming tools can be greatly improved.
(5) Diamond Coating (Diamond)
CVD diamond coatings provide the best performance for non-ferrous metal processing tools, it is the ideal coatings for the machining graphite, metal-based composites (MMC), high-silicon aluminum alloys and many other highly abrasive materials. (Note: Pure diamond coating tools cannot be used to machine steel, because the amount of cutting heat will be generated when machining the steel with chemical reactions that destroy the adhesion between the coating and the tool). The coating that suitable for hard milling, tapping and drilling is different with each other with specific use situation. In addition, you can also use multi-layer coating which embeds other coatings between the surface layer and the substrate, and the multi-layer coating can further increase tool life.