Mining and Chemicals Products, a rapid prototyping company based in Laverstock, Wiltshire, has developed low-melt exotic alloys to speed up the metalprototyping process.
The low-melt metal prototypes – composed of bismuth alloys – are created using a casting process, and the non-shrinking properties of the alloys enable more accurate castings.
Low-melt alloys, as the name suggests, melt at temperatures much lower than those associated with other alloys, in this case just above the boiling point of water.
The non-shrink properties mean less waste is created during casting, leading to more accurate dimensions and reducing the need for machining. Previously, metal prototypes have been made by selective laser sintering of a polymer-coated metal powder.
The moulds for the bismuth prototypes can be made from resin in a conventional rapid prototyping process. They can also use hand made plaster moulds.
Making the moulds is the most lengthy part of the production process. Pouring the alloy into the mould and breaking out the finished product is simply a matter of waiting for the alloy to solidify. Output per hour depends on the complexity and size ofthe design.
The main drawback to the new prototypes is that they are relatively soft – so can only really be used to test the fit and feel of a component.