Delphi Harrison 
Thermal Systems

Stereolithography Excellence Award Finalist, 1995

Stereolithography (SL) and vacuum sand casting improve Delphi's customer responsiveness – and their bottom line

The Challenge
Responding rapidly to customers' ever-changing needs is more than a motto to Delphi Harrison Thermal Systems of Lockport, New York. Since early 1994, Delphi has earned a reputation for providing a quick, low-cost method of producing medium scale runs of prototype parts in a fraction of the time required by their competitors.

Utilizing SL masters as the basis for producing vacuum sand casting tooling has become a vital and valuable selling tool that directly benefits Delphi's bottom line. Tooling is produced in one week, and castings in two weeks - when their competitors take six to eight weeks to produce similar prototypes.

Using a CAD file eliminates possible misinterpretation of paper drawings, and easily allows material to be added to the design to make it ready for tooling. Inside features with the appropriate modifications become the drag half of the mold and the outside features become the cope half of the mold.

Flanges, alignment holes, and shrink factor compensations are added to the solid CAD file. The SLA 500 system was used to output the design model, and after normal post-processing, the SL masters are painted with three coats of primer to further enhance the surface finish.

Taylor Pohlman, a casting house based in Orchard Park, New York, completed the casting process by mounting the SL masters to individual base-plate boards using the flange and alignment holes built into the SL master. A wooden gating system is attached to the SL cope masters to make them ready for casting.

The casting process begins by shrink wrapping a thin plastic film over the SL drag master. A thick steel box is fitted over the base plate board and very fine grain sand is poured over the master. A very high vacuum is pulled to mold the sand to the SL master. At this point, the SL drag master is removed. The steps are repeated for the cope master. The two halves are then fitted together, and 356 aluminum is poured into the mold. Once the aluminum hardens, the vacuum is released and the sand recycled, leaving a finished part.

Because the stereolithography masters can be repeatedly reused, virtually thousands of parts can be produced from each pair of drag and cope masters. The SL technology is also used to produce tooling for any cores that may be needed for each part.

Advantages of being first to market and being more responsive to market demands are not lost on Delphi. Their customers love their fast turnaround, quality castings, and responsiveness to customer needs, giving Delphi - and their customers - a clear competitive advantage.