Question $3$

a$)$ Define pattern allowance in moulding. Explain the purpose of providing the pattern allowance. $[4]$

b$)$ State and explain two properties of good moulding sand. $[4]$

c$)$ State and explain five purposes of core binders in sand casting. $[10]$

d$)$ Explain the term fettling as used in casting. $[3]$

e$)$ State and explain four reasons for having the casting defect hot air. $[4]$