Observation

This question posed much difficulty to the candidates as they could not provide correct answer to any part of the question. The required responses to the question are as follows:

(a)        (i)         filler metal for brazing
- Melting temperature of the metal to be joined.
- Choosing alloy that possesses a melting temperature well below that of   the    
metals to be brazed.

(ii)        welding electrode
-     type of metal to be welded

• type of welding machine to be used

(iii)       oxyacetylene cutting nozzle

-    The thickness of the metal plate to be cut.
-    The type of cut to be made.

• The diameter of the orifice.

(b)        (i)         Casting defects are undesirable features which occur in casting.
(ii)        Causes of casting defects:

• Faulty moulds;
• Faulty pattern designs;
• Incorrect pouring;
• Hasty removal of castings;
• Poor venting;
• Poor gating;
• Unsuitable moulding sand;
• Incorrect melting temperature.