Process gets to die-casting 'core' problemProcess gets to die-casting 'core' problem

Irvine CA--How do you improve the flow of a fluid through a pump, or eliminate the high temperature gasket and assembly steps in producing an automotive exhaust-gas recirculation (EGR) valve? Alyn Corp. says it has the answer in ALYNCORE(TM), a process that produces castings using soluble cores.

"Tooling costs whether using sand with binders, lost foam, or ALYNCORE will be very similar in design and cost," explains Tom Flessner, Alyn Corp.'s director of precision pressure casting. All three methods use H13 steel molds heat treated to withstand thousands of production cycles. Tool designs are nearly identical, since the overall product shape is the same.

It's the choice of core material, however, that will impact the finish and amount of secondary manufacturing required. "Sand core and lost foam can shift, resulting in less precise products that will require machining," Flessner clarifies. He adds that sand cores have a rougher finish than soluble or lost-foam core, if the lost foam is ceramically coated. "Our process is very stable, much more so than lost foam, and provides a better finish than sand or foam cores," Flessner claims.

ALYNCORE does require two tools to cast the cores, one for the core and one for the part. On the other hand, much like a steel casting tool, the finished ALYNCORE tool can be formed to create almost any internal shape. Flessner cites precisely shaped vortexes for intake manifolds, or a very smooth surface in water-pump cavities as examples.

Flessner also maintains that his company's process has other advantages over sand and lost-foam materials. For instance, the stable core can withstand the high potential pressures that occur during the process. He also notes that this process produces a smooth core that allows for better material flow and faster cavity fills with less movement. This results in internal passages that have a surface finish similar to the external surface, which translates into less secondary machining or assembly.

Of perhaps even greater interest to design engineers, Flessner feels, is that the ALYNCORE process permits designing parts within a part. The EGR valve, for example, can be cast as a single part, eliminating the high-temperature gasket and associated assembly operations.