Mechanical Engineering - Workshop Technology - Discussion

I think 1to 2 mm is correct.

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

1 to 2 mm/m is the correct answer.

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

10 to 15 mn/m is correct.

It should be 10-15.

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

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.