List of Tool Materials
The following are some of the important tool materials in use :
(a) High Carbon Steels
(b) High Speed Steels
(c) Cast Cobalt (Stellite) Tools
(d) Carbides
(e) Coated Carbides
(f) Ceramics
(g) Diamonds
(h) Cubic Boron Nitride (CBN)
(i) Polycrystalline Diamond
These are the earliest tool materials used. These are necessarily plain carbon steels with carbon percentages between 0.6 and 1.5% and some very small alloy additions such as manganese, silicon, tungsten, molybdenum, chromium and vanadium. The main disadvantage of these cutting tool materials is their inability to withstand high temperatures. Beyond 200oC they lose their hardness and cease to cut. So they are helpful only for very low cutting speeds (about 0.15 m/s) and to be used with low temperature generating operations such as machining wood, magnesium, brass and aluminium. They are easy to prepare and grind, and as a result they are used for form tool making for low quantity production, and hand tools, e.g. chiesels, saw, taps, dies, etc.