Mechanical Chisel Tool
Chisel is one of the most important tools of the sheet metal, fitting and forging shop. It is widely used for cutting and chipping the work piece. It is made of high carbon steel or tool steel. It is in the form of a rod having cutting edge at one end, hexagonal or octagonal body and striking head at the other end. The size of a chisel is described by its length and width of edge. When the cutting edge becomes blunt, it is again sharpened by grinding. For cutting the job or work piece with the chisel, it is placed vertically on the job or work piece and hammering is carried out upon its head. But for chipping, the chisel is inclined at 40°-70° with the job orwork piece. The angle of the cutting edge of the chisel is 35°-70°according to the metals to be cut. Source A Textbook of Basic Manufacturing Processes and Workshop Technology by Rajender Singh.
Chisels and punches are useful tools for machinists. The tool at the top of the illustration is a pin punch, used to drive out straight, taper, and roll pins. The drift punch below it is used as a starting punch for driving out pins. In the middle is a center punch that makes a starting point for drilling. The two bottom tools are cold chisels. Cold chisels are made in many shapes and are useful for cutting off rivet heads and welds.