Multiple choice general knowledge

Rapping allowance is provided on a pattern to take care of

  1. shrinkage

  2. distortion

  3. machining

  4. easy withdrawl
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In pattern making for casting, rapping (draft) allowance is the slight taper provided on vertical surfaces to enable easy withdrawal of the pattern from the mold without damaging it. Shrinkage allowance compensates for metal contraction during cooling, while machining allowance provides extra material for finishing operations.

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