Question 4
(a) What is hardening?
(b) Explain the following forging processes:
(i) twisting;
(ii) drawing down.
(c) With the aid of a sketch, describe how to form a bend over an anvil.
Observation
Most of the candidates who attempted this question had difficulty in explaining twisting and drawing down. The correct responses are:
Twisting: It is a process of turning a work piece either hot or cold. It involves
heating the section to be twisted evenly along the length and turning using both hands with a tap wrench or a bar with square or rectangular hole at the centre.
Drawing down: It is a process in which the cross section of a work piece is
reduced and its length increased. This is done by hammering the heated work piece.