Compacted Graphite Iron is also known as CGI and Vermicular Graphite Iron. This
material was developed around the same time as SG Iron – Ductile Cast Iron back
in the 1940’s but it is only recently that designers and engineers have started
to full utilise its unique mechanical qualities. In simplistic terms CGI is neither
a Grey Iron nor a SG Iron; it falls in to a category that is somewhere in-between.
The graphite formation in Grey Iron is in the form of a flake, SG Iron exhibits
graphite in the form of spheres.
Compacted Graphite has blunt flakes that are interconnected thus offering the beneficial
properties of Grey Iron and SG Iron
Compacted Graphite Iron Castings has a greater tensile strength than Grey Cast Iron.
Compacted Graphite is almost twice as strong as Grey Cast Iron but it retains the
ability to be produced cast near to shape, and has low manufacturing costs.
Good fatigue properties, ease of machining, good thermal and damping properties
make this an ideal choice for applications such as engine blocks, flywheels, clutch
components, piston rings, turbo housings, exhaust manifolds and brake drums.
