A pattern is basically a model of the component that is used by the foundry to make moulds from. They can be constructed from wood, resin, metal or a combination of these materials. The quality of a pattern usually determines the quality of the component, i.e. the better the pattern - the better the casting.

Once! Moulds are made from sand and after the metal has been cast into them they have to be broken up to extract the casting.

Moulds that can be used many times are called dies. These are made from metal and can be very expensive.

This is the tendency of metal to expand at higher temperatures and shrink or contract at lower temperatures. Consequently as the metal is in its liquid state when cast into a mould, it will shrink pro rata as it freezes and by the time it is cool, the casting will be smaller than the pattern from which it is made.

When a pattern is made, the patternmaker will calculate the contraction of the metal and add this to the dimensions so the casting will present the desired sizes when it has cooled.

Usually yes, a long as the contraction is not critical to the required dimensions. And the original casting is not too complex. It some instances it can be cheaper to have a pattern made.

Should you require castings from an original item - in many cases we can repair the original and prepare it for use as the pattern.