Mechanical Engineering - Workshop Technology - Discussion

The correct answer is all materials to be cast.

A pattern maker's shrinkage rule is a tool used to ensure that the pattern is made to the correct size, taking into account the shrinkage of the material during the casting process. The rule considers the shrinkage characteristics of all materials to be cast, including:

- Metals (e.g., steel, aluminium, bronze)
- Alloys (e.g., cast iron, ductile iron)
- Other materials (e.g., sand, investment)

The shrinkage rule helps the pattern maker to:

- Determine the correct size of the pattern
- Account for shrinkage during casting
- Ensure accurate dimensions of the final casting

Here's why the other options are incorrect:

- Only shrinkage allowance: The shrinkage rule considers more than just shrinkage allowance; it takes into account the specific material's behaviour during casting.
- All pattern allowances: The shrinkage rule is specifically concerned with shrinkage, not other pattern allowances like machining or draft.
- All materials of the pattern: The shrinkage rule is focused on the materials being cast, not the materials used to make the pattern itself (e.g., wood, plastic).

By using a shrinkage rule, pattern makers can create accurate patterns that result in castings with precise dimensions.

Different shrink rules are used for different material.

This oversized scale compensates shrinkage allowance, so one can measure the dimension as an ordinary ruler without worrying the contraction of the metal.

What is shrinkage rule?