| Tuscarora Inc., one of the world's largest producers of custom-molded foam plastics, has found a much faster and more accurate way to produce prototype samples. Tuscarora, based in New Brighton, Pa., often must produce highly accurate prototypes of molded packaging, cushioning, and other products of EPS, EPP, EPE, and other expandable-bead foams. In the past, Tuscarora would draw lines on a block of foam, carve out the part on a Bridgeport milling machine, and then fine-tune the part shape by hand cutting. This is a slow process:taking 1 to 8 hr, depending on part complexity:and not sufficiently accurate to meet today's customer standards. "We could hold a tolerance of 1/16 in. at best working by hand," said Bill Brokob, manager of Tuscarora's regional technical center in Colorado Springs, Colo. What's more, product shapes have become more complex. "Nothing's square any more," said Brokob. "It was impossible to follow curves accurately when we were cutting prototypes by hand."
Tuscarora first investigated CNC machining centers designed mainly for metalworking. These machines were much more heavy-duty than was needed for cutting foam and cost as much as $75,000. Then Tuscarora found a more suitable CNC routing/drilling machine from Techno-Isel of New Hyde Park, N.Y. It cost $25,000 for a 48 x 40 in. table size and z-axis height extension of 19.875 in., and it provided absolute accuracy of 0.003 in./ft plus resolution and repeatability of 0.0005 in. Now, after the CNC machine is programmed from a CAD file of the part, it automatically cuts the prototypes. Programming and set-up takes about 20 min, while the actual cutting takes 10 min to 4 hr, depending on part complexity. The router runs unattended except for loading and unloading. Tuscarora now has 10 Techno machines, at least one in each of its regional technical centers. |
