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Home Engineering Mechanics Production Technology Laboratory To design and prepare a pattern for the casting made by malleable cast iron with consideration of suitable allowances
Production Technology Laboratory Lab Experiments

To design and prepare a pattern for the casting made by malleable cast iron with consideration of suitable allowances



Objective

To design and prepare a pattern for the casting made by malleable cast iron with consideration of suitable allowances.

Materials Required

  • Teak wood

Equipment

  • Steel rule
  • Try square
  • Marking gauge
  • Rip saw
  • Tenon saw
  • Mortise chisel
  • Mallet
  • Jack plane
  • Wood rasp file

Procedure

1. Pattern Design (Shrinkage and Machining allowances are taken into consideration)

  • Calculate the amount of shrinkage allowance for each dimension of given casting drawing based on the cast material.
  • Calculate the amount of shrinkage allowance for given casting material.
  • Calculate the total amount of allowance provided on the pattern.
  • Sum the allowance and actual dimension.
  • Redraw the casting drawing with the dimensions including allowances.

2. Pattern Making

  • heck the dimensions of wooden piece using for pattern making and mark it according to the dimensions.
  • Sides of pieces are planned with jack plane for straightness.
  • Wooden piece is cut by using sawing tools according to the dimensions given in redrawn casting drawing..
  • Finish the same using wood rasp file.
  • Fix a the wooden piece in the drilling machine rigidly and Perform drilling operation according to the dimensions shown in fig.
casting-drawing

Observation Table

Dimension No. Actual Dimension Machining Allowance Total Dimension with M.A Shrinkage Allowance Total Dimension with S.A
1 0 0 0 0 0
2 0 0 0 0 0
3 0 0 0 0 0
4 0 0 0 0 1
5 0 0 0 0 0
6 0 0 0 0 0
7 0 0 0 0 0

Calculations

Final Sketch

Precautions

  • Reaper should be free from moisture
  • Marking is done without parallax error
  • Care should be taken while cutting and drilling.

Result