The Global Castings Industry
There are around 450 foundries in the UK. They are located in all parts of the UK, with the main concentrations in the Midlands and South Yorkshire (Sheffield) area. All the UK foundries are listed in the Foundry Yearbook and Casting Buyers Directory, available from ICME: see the Yearbook.
What is Casting?
Casting is a manufacturing process in which molten metal is poured into a mould cavity, allowed to cool and solidify within the mould, and then the mould is removed to leave the metal casting. Casting can be used to make parts of complex shapes that would be difficult or uneconomic to make by other methods (such as forging, assembling components or cutting from solid material).
Castings processes may be sub-divided into processes in which the mould is destroyed as part of the process and those in which the mould may be re-used (termed die-casting).
In sand casting the hollow mould is made of bonded sand using a wooden pattern, which is in the shape of the component to be made. Hollow sections can be introduced through the use of sand cores placed into the mould cavity. The pattern is removed and molten metal is poured into the cavity. Once the metal has solidified, the sand mould and any cores are removed. The pattern may be re-used and the sand can generally be recycled.
In diecasting, the mould is made of metal and is called a tool or die. The molten metal is introduced into the die by gravity or under low pressure or high pressure. The die may be re-used many thousands of times to produced thousands of components.
Investment casting, in which a wax copy of the component is used to produce a ceramic mould, has been in existance for thousands of years, yet is still used to produce large numbers of high quality castings for aerospace and medical applications.
Other variations of casting processes include rapid prototyping, centrifugal casting, continuous casting and processes in which a semi-solid metal billet is squeezed into the mould or die, eg rheocasting and thixoforming.
The choice of process is determined by the number of components required, the metal alloy to be cast, the price per part and properties such as surface finish, strength etc.
Applications of Castings
The single bigggest use for cast metals components is in the automotive industry as engine blocks, crankshafts, wheels and turbochargers and many more. They are also used in telecommunications (as mobile phone casings) in the aerospace and rail industries, in the oil, gas and chemical industries (as pumps, valves and pipes) and as tools and machines for other industries, such as steel and paper rolling plant. Castings can weigh as little as a few grammes to several hundred tonnes.
The industry therefore has to ensure that it has sufficient numbers of competent engineers and skilled people who are able to understand the requirements of other manufacturers.
The Global Industry
Globally there are 70.6 million tonnes of ferrous (iron based, steel) castings and 14.6 million tonnes of non-ferrous (aluminium, copper, zinc, magnesium etc) produced with China and the USA being the largest producers, based on 2005 figures, followed by Russia, Japan and India, (ref Modern Castings, 40th Census of World Casting Production, pub Dec 2006). These figures are predicted to grow in coming years.
In the UK there are around 25 thousand people directly employed in the castings industry and a further 8 thousand employed in the large supplier industry, supplying alloys, materials, design, die/pattern-making and finishing processes.
The industry has invested heavily in recent years to reduce costs, to increase productivity and to meet the current environmental legislation. Many of the newer operations have high environmental standards and use the most advanced technology.
For more information about the castings industry, different casting processes or properties of casting alloys please contact ICME.