shell mould BrE technical
shell mold AmE technical

Pressure, chill, investment and shell mould castings are produced.

Strengthening and sealing vulnerable areas in shell moulds.

The slurry and grit combination is called ceramic shell mould material, although it is not literally made of ceramic.

A shell mould consists of a sand shell, varying in thickness between 4-10 mm. The sand particles are bonded together with phenolic resins giving a permeable mould.

According to Rodney Dale, the upper shell mould was "one of the largest - if not the largest - injection mouldings of its type in the UK: possibly even in the world."

Ceramic shell casting techniques using silica, zirconia and other refractory materials are currently used by the metal parts industry for 'net casting', forming precision shell moulds for molten metal casting.

EXPERTISE Since 1959, Trucast has been utilising two electric Induction Furnaces and a Jobbing and Shell Mould process to produce castings from a few grams up to 300kgs.

The shell mold casting process consists of the following steps:

The shell mold is then placed into a flask and supported by a backing material.

The pattern, a metal piece in the shape of the desired part, is reused to form multiple shell molds.

Other methods of casting, such as those using shell molds, boast higher quality of surface finish, but higher cost.

Setup and production of shell mold patterns takes weeks, after which an output of 5-50 pieces/hr-mold is attainable.

For casting the shell mold is placed inside a flask and surrounded with shot, sand, or gravel to reinforce the shell.

Shell mold casting requires the use of a metal pattern, oven, sand-resin mixture, dump box, and molten metal.

A shell mold is formed by heating the metal pattern and then bringing a sand and resin mixture into contact with the pattern.

Mold assembly - The two shell halves are joined together and securely clamped to form the complete shell mold.

However, in shell mold casting, the mold is a thin-walled shell created from applying a sand-resin mixture around a pattern.

Shell mold casting is a metal casting process similar to sand casting, in that molten metal is poured into an expendable mold.

Shell mold casting allows the use of both ferrous and non-ferrous metals, most commonly using cast iron, carbon steel, alloy steel, stainless steel, aluminum alloys, and copper alloys.