Workshop Technology
The process used to improve fatigue resistance of the metal by setting up compressive stresses in its surface, is known as

Extrusion
Cold heading
Hot piercing
Cold peening

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Workshop Technology
Riddle is used for

Cleaning the moulding sand
Reinforcement of sand in the top part of moulding box
Smoothing and cleaning out depressions in the mould
Moistening the sand around the edge before removing pattern

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