Posted by jim in n.y. on Tuesday, October 26, 2004 at 9:10PM :
In Reply to: Re: mo'par norm, please elucidate some erudition posted by johnm on Tuesday, October 26, 2004 at 8:17PM :
castings in an automotive application are generally of the iron type( iron and graphite). where as forgings are of an alloy type made up of many different elements such as chrome, molybdenum,iron, carbon,nickle ,etc. the amount of each depends on the intended application. all the ingredients (if you will) are added together in a furnace and then cast as billets or ingots. it is then processed further in a rolling mill or forging dies which compresses and aligns the grains to the shape of the piece. this ,along with the alloy content is what gives it it's desireable characteristics over a casting. they do also make alloy castings which offer strength over plain cast iron whith out the cost of making forging dies.kind of a middle of the road if you will. a relatively new process that is being used more and more is powder metal technology.similar to how tungsten carbide is made. all the elements are added together in a mold of the desired shape and then heated to the melting point and cooled.the part needs virtually no machining and is much more cost effective.
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