Question 3
(a) (i) What is casting?
(ii) State three sequential processes involved in casting.
(iii) What is porosity?
(b) With the aid of a labelled sketch, explain upsetting in forging.
Observation
Candidates’ overall performance in this question was good. Some candidates, however, could not satisfactorily answer questions 3(a)(ii) and 3(a)(iii). The solution of those poorly answered questions are as follows.
(a) (ii) Sequential Processes Involved in Casting
- Making a pattern
- Preparing a mould (cavity)
- Pouring the molten metal into the mould (cavity)
(iii) Porosity
Porosity is any void or hole in a casting caused by gas
formation usually when air is trapped in the metal during
pouring.