Grey iron is one of the oldest and a highly versatile metal used for casting by foundries to date. The metal is also among the most abundant and cheapest of all available metal materials. Grey iron castings are produced using melted grey iron molecules, which are poured into a mold, and are extracted once cooled. The properties of casting are greatly affected by the foundry practice along with the cooling rate. Grey irons contain large concentration of carbons that allows for, ease of casting, melting, and machining. Designs for grey iron castings vary hugely due to its near absence of shrinkage during cooling. Grey iron castings are known for their high tensile strength that may be in a range of 20,000 psi to more than 60,000 psi.
Green sand molding is one of the most widely used techniques for producing castings. The method is generally used to produce small or medium sized cast products, however can be used to develop castings up to 1000 pounds. The shell molding process is used for heavier applications. With shell molding, it is possible to cool the mold, which contains the heated metal. The process allows for a cleaner resultant product than any other method of production. Centrifugal casting is another method, which is used for production of pipe and large cylinders and comprises water-cooled molds.
Grey castings have found extensive applications in automotive, appliance, agricultural and machinery applications. Some examples of components produced using grey iron are pump and turbine housings as well as bases for compressors and dynamometers.What to look for?
While buying grey castings, the first and foremost thing to consider is foundry quality in procedures and resultant products. As the characteristics of grey iron castings depend greatly on foundry practices, finding the most suitable one will result in a consumer's requirements being met.
The concentration of carbon in casting is another important factor to consider. The common percentage for carbon concentration amounts in the range from 2.5 to 4 percent. An addition of about .1 percent carbon in grey castings will result in the tensile strength decreases by around 2700 psi. Different foundries utilize different casting procedures.