Process Encyclopaedia

Other names / variants: Investment casting

Some form of lost wax casting has been used since 4000BC.
It is now mainly used for medium size batches where good quality is required.
The fine dust and harmful fumes require careful control of the workplace to avoid health problems for operators.

Suitable for most metals, leaving a good surface finish which usually does not require further finishing steps.
Best for small complex-shape parts, but can be used for parts from 5g to 100kg.
Not much metal scrap, and it can be easily recycled. Wax can be re-used but ceramic coating must be disposed of carefully.

The production cycle is slow: usually only 1-5 castings can be made an hour, depending on the size. Assembling lots of patterns on one tree can help in achieving a reasonable production rate.
The basic cost of the equipment can be as little as Ł1,000, although automated kit can be a lot more. The cost of the patterns is usually only a few hundred pounds, but they can take several weeks to make.
Although the setup costs are low, the low manual production rate means that only batch sizes of up to 50 are economic; this can rise to a few thousand if automated.