for steel], where chemistry is tough to control,” Mueller said. “Most iron parts are higher volumes, whereas in steel you have lower volumes, more complex parts, more cores and more mold-aids to make them work. In iron, the process isn’t as elaborate.” Many designers still believe steel is


simply too heavy for their application. However, with a well-designed part, end-users can receive a component that is highly functional while taking some of the weight out of the part, ac- cording to steel casting experts.


If They’re So Small, Where Do I Find Them?


Steel is more than just a strong mate-


rial. According to Mueller, steel parts often are specifi ed when weight isn’t critical and strength and wear consid- erations are. However, the material can be just as important for its ability to be welded, both for maintenance pur- poses and for use in larger assemblies. “A lot of [small steel] components


are used in lager fabrications because they are attached by welding,” he said. “I think the wear characteristics and the welding that is done to the castings are the most important [considerations when specifying steel].” As opposed to iron castings, Muel-


ler said steel castings can be alloy- enriched to achieve the wear resistance required, where iron castings would have to be heat treated. “In [one of our applications], the


gear teeth cannot ‘mushroom’ over or become rounded, so steel is the mate- rial of choice,” he said. Many applications in the construc-


tion machinery and equipment market fall under the small steel classifi cation, including hydraulic cylinder heads (average weight of about 38.5 lbs.),


“ I think where a lot of people in the past


have defaulted away from steel, with new technology, they are [turning to it].


“


— Bob Mueller, P&H Mining Equipment


JANUARY/FEBRUARY 2011 METAL CASTING DESIGN AND PURCHASING 45


cylinder mountings (24.5 lbs.), trunions (34 lbs.), rod ends (11 lbs.), guides (30 lbs.) and link guides (13.5 lbs.). Small steel castings are less prevalent in the oil fi eld market, but sheave guards and plates generally weigh in under 50 lbs., swivel goosenecks are around 50 lbs., and housings can be as small as 50 lbs. In the truck market, the smallest steel parts are typically in suspension appli- cations and generally weigh between 70 and 100 lbs. According to the American Foundry


Society’s most recent forecast, the growth markets for steel in the next decade will be industrial valve (8.7% short-term annual growth rate [AGR]; 2.6% long-term AGR), oil and gas fi eld equipment (1.3% long-term AGR), industrial and commercial fan and blower (2.9% short-term AGR; 0.1% long-term AGR), turbine and turbine generator set units (7.2% short-term AGR; 3.7% long-term AGR), and rail- road rolling stock (19% short-term AGR; 6.6% long-term AGR).


METAL


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