Sandcastings

The sandcasting process involves the use of a pattern made from wood, resin or aluminium, around which a moulding box is placed and sand is packed around it. TheĀ  box is then turned over and the pattern is removed from the sand. This box then has a cavity in the sand which represents one half of the casting. The process is repeated for the top half and a running system is cut into the sand to allow metal into the cavity. The two halves of the mould are pinned together ready for metal.

LEW has its own pattern shop so we can supply patterns for all the sandcastings we are asked to produce.

LEW employ two different sandcasting methods, Airset and Greensand. Each has its own advantages. Airset is used for casting grey iron and SG iron as well as larger castings in aluminium and bronze. Greensand is used for smaller castings in aluminium and in bronze and gunmetal.

Airset involves mixing sand, acid and resin together at which point the mix begins to harden as it comes into contact with air. This provides a strong mould which is especially useful for larger moulds. Waste sand is recycled and 90% is recovered.

LEW use greensand moulds for smaller castings in aluminium and bronze including small plaques and signs. Greensand is a mixture of fine sand and clay and gives a finer finish than airset and is 100% recyclable.

The materials cast using the sandcasting process are:

1. Grey Cast Iron:
LEW can cast up to 300kg in cast iron which is available in a variety of grades depending on the application of the casting.The molecular structure of grey iron is flake which is adequate for most applications but where brittleness could be a problem then SG Iron should be used.

2. SG Iron :
SG stands for Spheroidal Graphite and is also available in a variety of grades. The molecular structure of SG Iron is spheroidal rather than flake which makes castings in this material much stronger than grey cast iron and less likely to fracture under stress. Castings up to 200kg can be cast in this material.
Corrosion Resistant Iron (Ni-Resist) and Abrasion Resistant Iron (Ni-Hard) are also produced.

3. Aluminium Alloys :
A number of aluminium alloys are available, each with its own distinct properties.
LEW produce aluminium castings in LM4, LM6, LM25 and LM31 which cover the great majority of applications.

4. Bronzes :
The most common bronzes used at LEW are the gunmetals LG2 and LG4; Phosphor Bronzes PB1 and PB2 and Aluminium Bronzes AB1 and AB2.
Other specialized bronzes are also available.

Sandcastings are available in:

  • Grey Iron BS 1452
  • S. G. Iron BS 2789
  • Corrosion Resistant Iron BS 3468
  • Abrasion Resistant Iron BS 4844
  • Aluminium BS 1490
  • Bronze BS 1400
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