Q. Explain Machining allowance?
Machining allowance or finish allowance indicates how much larger the rough casting should be over the finished casting to allow sufficient material to ensure that machining will "clean up" the surfaces. The amount of finishing allowance depends upon the material of the casting, its size, volume of production, method of moulding, configuration of the casting.
|
Material Cast
|
Overall length of external surfaces, cm
|
|
0 to 30
|
30 to 60
|
60 to 105
|
105 to 150
|
|
Al alloys
|
1.6
|
3.2
|
3.0
|
4.8
|
|
Brass, Bronze
|
1.6
|
3.2
|
3.0
|
4.8
|
|
C.I
|
2.4
|
3.2
|
4.8
|
6.4
|
|
C.S
|
3.2
|
4.8
|
6.0
|
9.6
|
Table: Typical Machining Allowance for Sand Casting