During the complete premachining of the piston, all cracked and burnt areas are
machined away. Lifting holes are drilled out. The piston is preheated to
200C. Then Built up by submerged arc process. Temperature is maintained
until welding is complete. Immediately after, the piston is stress relieved
at a temperature appropriate for the material used.
The piston crown is then premachined according to specifications of engine
makers, then hard chrome plated on ring grooves and ground to engine