The GATE Grind

GATE 2024 ME – Question 31

Casting, Forming and Joining Processes · Casting: patterns, moulds, cores, solidification, riser and gating design, defects · 1 mark · Multiple choice

The allowance provided to a pattern for easy withdrawal from a sand mold is

  1. finishing allowance
  2. shrinkage allowance
  3. distortion allowance
  4. shake allowance

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Correct answer: (D) shake allowance

Explanation

To withdraw a pattern the moulder first taps (raps) it to loosen it from the sand, which makes the cavity slightly larger. The pattern is made a little smaller to compensate, and this is the shake or rapping allowance. Finishing allowance is for machining, shrinkage allowance is for contraction on cooling, and distortion allowance is for warping.