Investment Castings – Metal Forming Technique

Jan 10, 2017 | General

Investment castings or lost wax castings is a metal forming technique which has been around for thousands of years where hot molten metal is poured into a ceramic cast to form a solid metal part.  Modern day castings are made up of different alloys and specialist metals depending on the specification and use of the part.  Certain parts may need to be able to withstand extreme temperatures or be a certain weight depending on the environment it is being used in.

The manufacturing process has remained relatively true to its roots even with advances in technology.  The difference being companies can now mass produce parts and the main advances have been in the tooling for the wax moulds. Better tooling enables for a smoother more detailed finish to the part.

After the tooling is produced, wax is injected into the mould are and the individual parts are then attached to a sprue with a runner also known as a Tree.  The size of the part will determine how many can be produced at once. The Tree is then dipped into ceramic slurry and sandblasted. This process is repeated until the ceramic is thick enough to withstand the temperatures of the molten metal.

The Tree is now heated to remove to original wax moulding leaving the hollow ceramic shell and the hot molten metal is now poured.  After cooling the ceramic shell is now removed by force using vibration or a hammer.  The individual parts are now ready to be removed and polished and treated as per spec.

The main advantage of using investment castings is that high strength precision parts can be produced in a wide range of complex designs.  There is also the ability to use a wide range of materials in the makeup which is useful in manufacturing industries such as aerospace and automotive.

The only drawback to the process is that it is a labour intensive process which creates long lead times.  Manufacturers prefer investment casting to other processes because it produces more accurate parts with a smoother finish.

Acovet Precision Metals have recently partnered with Richter, a German based company with foundries in China. This partnership has enabled Avocet to source and distribute materials more competitively into the UK market.