Mechanical Engineering - Workshop Technology - Discussion

The amount of draft recommended on external surfaces varies from 10 to 20 mm/m.

Please explain this answer to get it.

The correct answer is 1 to 3° (approximately 2 to 5 mm/m).

The draft or taper allowance on casting is the slight taper or angle provided on the vertical surfaces of the pattern to facilitate easy removal from the mould. This allowance is typically:

- 1 to 3° (approximately 2 to 5 mm/m) for small castings
- 2 to 5° (approximately 5 to 10 mm/m) for medium-sized castings
- 3 to 5° (approximately 10 to 15 mm/m) for large castings

The draft allowance depends on the:
- Size and complexity of the casting
- Type of moulding material (sand, investment, etc.)
- Casting material (aluminium, steel, etc.)

The draft allowance ensures that the casting can be removed from the mould without damage or excessive force, which could lead to mould breakage or casting defects.

=> The exact draft allowance may vary depending on the specific casting process and application.

As per my knowledge, 10-20mm external and 30-40 internal taper allowance.

It should be 10-15.

10 to 15 mn/m is correct.

1 to 2 mm/m is the correct answer.

Answer is C.

Outer taper is 10 to 25.
Inner taper is 40 to 65.

I think 1to 2 mm is correct.

10-15 mm/m is an allowance for shrinkage.

Which means tapper section is provided only perpendicular face with parting line?