High Speed Steel (HSS)
Cheap price, good toughness, but poor wear resistance. Suitable for low-speed processing and manual operation, or processing very soft materials.
Cobalt High Speed Steel (HSS Co)
Adding cobalt element to HSS results in better red hardness (the ability to maintain hardness at high temperatures) and wear resistance compared to HSS.
Solid Carbide
The mainstream choice for modern CNC machining. Extremely high hardness, very wear-resistant, allowing for high speed and high feed rate.
The disadvantage is high brittleness, fear of impact and vibration, and relatively expensive price.
Coatings
Coating on hard alloy substrate significantly improves performance. Common coatings include:
TiN (titanium nitride): golden yellow, universal coating, wear-resistant.
TiAlN (nitrogen aluminum titanium): purple black, excellent high temperature resistance, suitable for high-speed dry cutting.
TiSiN and other advanced coatings with superior performance.
