Process Encyclopaedia

Overview

• 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.

Process details

Materials and shapes

• 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.

Economics

• 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 £1,000, 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.

Typical products

• Jewellery
• dental implants
• hip replacements
• valves
• wind instrument keys

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