Additive Manufacturing

MAY 2018

ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.

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Page 32 of 43

AM / Unmasking Process Costs 31 And he notes that the production rate is also more pre- dictable now. Reliance on manual effort to ensure proper masking of each piece has traditionally meant that productivity differed from person to person and from day to day. Even the rate through the quality assurance process could vary, because where 3D printing allows for detailed masks that fit the part perfectly, previously the company's masking solutions were more crude. Masking in the absence of custom fit required finesse to ensure the simpler masks work, and finesse some- times fails. PMT Quality Inspector Athena Reynolds describes the effect the move to 3D printing has had in the case of one representative part, an infusion pump housing component. Improved masking of this part translates into reduced need for her to clean misplaced coating from individual pieces in order to complete them. As a result, the number of housings she can inspect in an eight-hour shift has gone from 400 to 500 up to 1,000 to 1,200. In short, AM wins productivity improvements both prior to the coating operation and after it as well. Production Quantities Where PMT's masking tools differ most strikingly from other types of tooling is in the area of quantity. A more typical tool— think jigs, fixtures or molds—can be used again and again for piece after piece. The same mold might make a million units. But PMT's coating operation is a batch process in which racks of plastic pieces are loaded into a vacuum chamber together. Every individual piece needs its own masking. As a result, PMT's creation of tooling is essentially a production operation. The two 3D printers run around the clock and through the week- ends to generate hundreds of identical tooling components with each build. "It seems strange to think about now, but previously, we doubted we could justify our own 3D printing," Anaforian says. In any process, ineffi- ciencies and shortcomings tend to be invisible because they are familiar. Keep- ing surfaces masked from coating in the past has involved, in various cases, silicon pads or plugs cut or molded to size; hard tooling built from machined components made by a nearby machine shop; and occasionally 3D-printed parts from a service bureau. The machine shop and the service bureau both represented options for creating custom tooling, and in theory these options seemed sufficient. In practice, however, the limitation the coater had come to accept was a generally imperfect fit resulting from a series of simple custom compo- nents being assembled together. The cost and distance of an external service provider limited how daring PMT was willing to be in devising elaborate tools that might fit detail for detail without any assembly required. Only a chance encounter with Plural Additive Manufacturing (related to a customer part that was 3D-printed) led PMT to question this acceptance. The team members here realized that both the cost and the learn- The tooling used in the process serves to mask the part so that only the correct surfaces receive the metal coating. The actual masking surfaces face inward—metal coating is applied from inside the drum. The coating with metal vapor requires a vacuum chamber. This job will spend around 45 minutes in the chamber to ensure coating is complete.

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