The Waukesha facility has dedicated 9,000 sq. ft. to the lost foam line, including this flask conveyor system.
ramp up production so we fully understand each other’s needs and capabilities. Our objective is to work together and avoid putting ourselves or them at risk. Tere are possibili- ties we’re looking to explore both within Navistar and externally with other customers.”
Finding Lost Foam’s Sweet Spot At Pure Power, the production
cast iron lost foam process features an expendable polystyrene pattern, with a refractory coating and attached gating and risering system. Te pattern is placed in a carbon ceramic mold media that covers both external and internal surfaces. Te assembly is suspended in a flask and placed on a com- paction table. As the dry, unbonded mold media is poured into the flask, the vibratory forces cause it to flow around and into the pattern. When the molten metal is poured under a vaccuum, the foam pattern vaporizes. After solidifi-
cation, the unbonded mold media is dumped out, leaving the casting and an attached gating system. Able to produce near-net shape
castings typically not achievable in other casting processes, the lost foam process is an attractive alternative to green sand because part designs can include more complex cast-in ele- ments, minimal draft angles and tight tolerances. It also reduces or eliminates machining, improves surface finish and eliminates fins around parting lines. Increasing the freedom avail- able to part designers, lost foam can decrease weight and lead to multiple
parts being cast as a single component. (Pure Power’s flask size measures 35 x 54 x 47 in. and it is capable of produc- ing castings from 5 to 700 lbs. and with a maximum diameter of 30 in.) In early 2011, the company brought in Mike Johnston and Art Banuelos, lost foam experts with the Alabama- based consulting firm Lost Foam Group International, to help with on-site training and additional prepara- tions. Pure Power made the upfront investment with the acquisition and installation of the equipment, but the integration of lost foam was more than flipping a machine’s switch. “Te most important
“Lost foam allows us to make parts that we can’t produce in
green sand. It allows us to offer a wider variety of products to our customer base.”—Mitch Cheatham
things are a resource pool and a commitment to getting into lost foam,” Johnston said. “You need the right people in place— not necessarily people with lost foam experience but individuals in the right disciplines. You need some- body who understands the equipment, you need to have somebody committed
December 2013 MODERN CASTING | 25
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