|At Grede Foundries LLC in Columbiana, AL, a foam pattern is assembled into a molding ‘cluster’ for coating with a ceramic layer prior to pouring.|
| Grede Foundries’ Columbiana, AL, plant pours up to 48,500 tons/year of gray and ductile iron as lost foam castings. Metallurgical quality control and pouring consistency are critical to lost foam casting. |
It’s finally happening. Lost foam casting, the process that’s capable of flexible, volume production of highly detailed designs, is achieving the recognition from product designers and casting buyers that many metalcasters have been predicting for a decade or more.
The virtues of the lost foam process have been announced many times: It is effective for producing intricate designs that in many cases are impossible for other casting methods to accomplish. It requires no additives, binders, or cores, so it has environmental advantages, and it usually results in very little scrap. The equipment requirements are not especially demanding, and the finished products often require little grinding or machining.
The process demands skill and precision, but it’s straightforward: foam patterns are assembled into unitary assemblies that act as patterns for complex shapes and structures. When the metal is poured into the mold it volatizes the foam and forms the part defined by the pattern.
Among the world’s largest producers of lost foam castings is Grede Foundries LLC, and its largest operation, the Columbiana, AL, foundry. Lost foam production started there in 1987, with a full commitment to the process soon thereafter. Today, it specializes in medium- and high-volume runs of gray and ductile iron lost foam castings, weighing as little as four pounds or up to 800 lb. Car and truck markets, with their well-known requirements for volume and complexity, are where the new enthusiasm for lost foam castings is being demonstrated, and Columbiana is supplying them with pump housings, manifolds, turbocharger housings, carriers and cases, brackets, and driveline slip yokes, among other castings.
The plant’s production equipment includes three foam production lines, 14 foam presses and 10 automated glue machines.
“Lost foam is a natural solution for our medium- and heavyduty truck customers who constantly look for ways to reduce component weight and mass to help reduce harmful emissions and improve fuel economy,” said Tony Lovell, Grede’s VP of Sales & Marketing. “Reduced complexity with greater design flexibility through component integration is also achieved, providing better manufacturability by saving machining and assembly steps, as well as reducing inventory, all of which help in terms of the cost equation.”
Because lost foam casting is capable of achieving such complex designs, product designers have much greater opportunity to optimize engineering objectives, according to Grede, and this flexibility increases operational efficiencies and product value simultaneously. While other casting methods generally constrain engineers and purchasing teams, Grede indicates its customers’ design and purchasing teams work with its lost foam casting engineers from initial part concept through full production volumes, and obtain strategic advantages as a result.
Navistar is hoping to achieve the same success by converting its Waukesha, WA foundry to produce ductile iron foam castings as part of its PurePower Technologies’ plan. Accoriding to Eric Tharp, who manages the Waukesha and Indianapolis foundries for Navistar, Indianapolis will specialize in engine block casting for Navistar and others; Waukesha will produce a variety of smaller casting for the PurePower brand’s EGR valves, as well as other OEMs.
“Our model is to dedicate 50% of our output to Navistar and 50% to other OEMs,” Tharp reported. “That will allow us to handle the peaks and valleys of the market – not only the automotive sector, because we are in other markets, as well.”
When Navistar was supplying powertrain parts under contract to Ford Motor Co. it frequently had trouble achieving profitability, even when it was operating the Waukesha foundry at or near capacity. The new 50-50 strategy aims to overcome that problem. And, lost foam casting will be one of Waukesha’s advantages.
After acquiring its lost foam line at an affordable rate from an idle operation, Navistar is gearing up production. Operators are preparing for the new production process, and foam patterns will be sourced from suppliers and assembled and cured on-site. Tharp predicted that by the end of this year Waukesha will be able to pour six flasks/hour, about 3,600 lb., of lost foam products.