Process improvements in sand casting over the past 60 years (part 2) - Haworth Castings

Process improvements in sand casting over the past 60 years (part 2)

Published - 25th Jul 2018

The history of sand casting stretches back many thousands of years, as we’ve explored in previous blogs. The basic principles involved in sand casting remain unchanged, but new technologies have helped to bring about many improvements over the past few decades.

In the second of three blogs, we look at how process improvements have enabled us to develop our capabilities and offerings with regards to new additives and core making to customers since Haworth Castings was formed in the 1950s.

New additives

When ‘dry’ sand was first introduced, it was purged with carbon dioxide to make the moulds firmer. But, carbon dioxide presented some health and safety risks due to its combustibility.

These days we use Poliset cold-set binders to bind the sand particles together and these materials do not present the same health and safety risks.

The cold-set binders offer many benefits such as:

  • excellent sand flowability
  • high strength
  • rapid curing
  • good surface finish
  • low odour

The residual chemicals can also be removed very easily from the sand during the reclamation process – which is another key benefit.

Improved core making

The process of core making has also evolved significantly over the past few decades. Cores are added to the sand moulds to create cavities and intricate features. Traditionally, the cold box and ‘hand ramming’ methods have been used to make cores.

However, the advent of shell core making has brought many benefits – including improved core consistency and accuracy. Using this process, resin-coated sand is blown into a pre-heated core box. This bonds the sand particles together. Shell core making is ideal for castings when high precision is needed. So, for example, it is used to make aircraft impellor parts.

At Haworth Castings, we advise our customers on the best and most cost-effective core making technique for their project.

In the next blog, we will be looking at the introduction of recycling at the foundry and other machinery developments.

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