The figure to the right shows the relationship between various tool materials, in relation with hardness on a vertical axis and toughness a horizontal axis.
There are 6 main cutting tool materials used:
high-speed steels, cemented carbides, cermets, ceramics, sintered CBN (cubic boron nitride) and sintered diamond.
Some of these tool materials can be coated using either a CVD (chemical vapour deposition) or PVD (physical vapour deposition) coating process.
Today, cemented carbide, coated carbide and TiC-TiN-based cermet are key tool materials in the market. This is because they have the best balance of hardness and toughness.