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.

Observation Table

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