Drill Specifications
According to Indian standards the drills are specified by their diameters, series they belong to, the material they are made of and the I.S. number. These data are mainly based on the material for which the drill is to be normally used. They are made in three types :
(a) Type N - for normal low carbon steel,
(b) Type H - for hard materials, and
(c) Type S - for soft and tough materials.