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3-D printers help mold makers create prototype tooling

By: Rhoda Miel

November 12, 2013

Prototype mold makers are adopting 3-D printers to make injection mold tooling capable of turning out parts in standard machines with standard resins.

While the printers have some limitations, toolmaker Diversified Plastics Inc. has produced molds capable of turning out parts in ABS, 30 percent glass-filled nylon, polycarbonate, acetone and thermoplastic elastomer.

"It's all about R&D at this point, and we've been working closely with [3-D printer maker] Stratasys," said Annette Lund, vice president for Minneapolis-based Diversified Plastics, during a Nov. 12 telephone interview. "This is a great tool, and we're looking to the future now."

Stratasys Ltd. of Edina, Minn., has also worked with German mold maker Seuffer GmbH & Co. KG for injection mold tooling.

Seuffer, of Calw, Germany, says it can save about 97 percent of the cost of a standard prototype mold, and produce them within days rather than eight weeks.

Diversified Plastics added an Object 260 3-D printer from Stratasys earlier this year to use both for prototype parts and for injection mold tooling. The company has mold making and injection molding in house, which allows it to test both molds and the final molded part.

It takes longer to add water lines and other systems to the prototype tool than it does to print the actual tool itself, Lund said, while using the printer also gives the company greater flexibility to try out different cores and cavities.

About 20 percent of Diversified Plastics' business is in the medical industry. The requirements from health and safety agencies to fully test and validate medical equipment makes prototype tooling using the actual resins for production much more important, she said, and the rapid turnaround available from 3-D printing – along with the ability to make 10 to 20 parts for testing – makes a lot of sense for those customers.

Seuffer targets its prototype molds for the auto industry, where engineers must sample complex parts with the same heat and environmental issues the final component will face. Using the printed mold with standard processing and resins allows its customers to fully test an under-the-hood part, for instance, that must stand up to heat and oil.

But 3-D printing does have some limitations for mold making. The size of 3-D printers limits the tools to small to medium molds. It cannot produce molds for parts with thin walls, and cannot be used for high heat resins, Lund said, but she added Diversified has been able to do far more with printed molds than it first thought possible.