Types of Pattern Allowances

Different Types of Pattern Allowances

  1. Shrinkage Allowance or Contraction Allowance
  2. Machining Allowance or Finishing Allowance
  3. Draft Allowance or Taper Allowance
  4. Rapping Allowance or Shake Allowance
  5. Distortion Allowance or Camber Allowance
  1. Shrinkage Allowance or Contraction Allowance : Generally during the time of solidification of the molten metal in the mold, molten metal shrinks in the cavity so the casting produced becomes smaller than the cavity and pattern. To compensate the shrinkage of the molten metal, the pattern is made larger than the casting produced. The allowance provided to compensate the shrinkage is called shrinkage allowance or Contraction allowance.

 

Question and Answer

  1. A Taper provided on the pattern for it’s easy and clean withdrawal from the mould is known as
    Answer: Draft Allowance or Taper Allowance
  2. Shrinkage allowance is added to pattern dimensions to care of
    Answer: Solid shrinkage