Compacted Graphite Iron Castings

Compacted Graphite Iron was first patented at about the same time as ductile iron in the late 1940’s. At the time it was viewed more as a curiosity rather than a production material, but its unique properties has led it to be used in many applications which are unsuitable for grey or ductile iron. CGI has twice the strength of grey iron and costs no more to produce than ductile iron. 

About Compacted Graphite Iron Castings

Compacted Graphite Iron, which is also known as CGI or Vermicular Graphite Iron, is a form of cast iron in which the shape of the graphite particles is between that of conventional grey iron flakes and ductile iron where the graphite is in spheres. The worm-like compacted-graphite shape provides physical properties that mirror the most beneficial properties of grey and ductile irons.

Grey iron is particularly easy to cast and machine and it has good damping and thermal conductivity, but its flaky structure makes it brittle, as reflected by its low tensile strength. At the other end of the spectrum, ductile iron has a high tensile strength but relatively poor thermal conductivity and damping properties. Compared with these two extremes, CGI has thermal conductivity and damping properties roughly the same as grey iron and tensile strengths and stiffness comparable to those of ductile iron.

Compacted Graphite Iron Production

At Durham Foundry we have been producing compacted graphite iron castings for the last 30 years. As well as compacted graphite iron castings, our customer base also covers grey, ductile and alloyed irons for the engineering, decorative, architectural and artistic sectors and we can supply castings from one off up to small to medium batch production using Alkali Phenolic resin bonded sands.

Our workforce of highly skilled moulders can work from complex loose pattern equipment, particularly where low volumes are required, whilst our moulding line is suited for batch production. Our long trading history, coupled with an investment programme that has enabled us to keep up with modern production methods and environmental legislation has meant that we have been involved with many projects requiring compacted graphite iron castings and continue to be so.

All our compacted graphite iron castings are produced to the current ISO material specification, ISO 16112, along with any further certification which a customer may require. Manufacturing takes place within our ISO 9001 and ISO 14001 Management Systems. Call Durham Foundry on 0114 249 4977 to discuss your Compacted Graphite Iron project.