Additive Manufacturing

MAR 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 17 of 67

MARCH 2018 Additive Manufacturing 16 TAKING SHAPE manufacturing. According to Carbon, its "unique programmable resin platform offers unparalleled performance with respect to material durability and elastomeric respon- siveness." Adidas plans to produce 100,000 pairs by end of 2018. Nike is also exploring 3D-printed footwear. Footwear News reported in 2017 that Nike is beginning to use 3D printing to develop shoe prototypes, according to the French 3D printing company Prodways. Nike isn't a stranger to 3D-printed shoes, although it's been on a smaller scale for professional athletes. For instance, in 2014, the company released a 3D-printed cleat plate built for the shuttle drill. It also produced a 3D-printed shoe built for linear speed in the 40-yard-dash. In 2016, New Balance released Zante Generate, a running shoe with a full-length 3D-printed midsole. Through an exclusive collaboration with 3D Systems, the compa- ny utilized the company's laser sintering powder, DuraForm TPU Elastomer, to make significant advancements in the performance of printed parts for running shoes. For the Zante Generate midsole, New Balance used selective laser sintering (SLS). The first release wasn't available for mass consumption; there were only 44 pairs total. Bob Zollo believes we've been doing it all wrong: using the wrong materials, building inaccurate machines and improperly designing parts for additive manufacturing. Rather than selecting from existing options, Zollo has actively developed 3D printing materials, technology and design guidelines specifically for his application, 3D-printed injection molds. Zollo is a founder and CEO of Avante Technology, a new Cheyenne, Wyoming- based compan y focused on educating and assisting companies seeking to incorporate desktop fused deposition modeling (FDM) 3D printing as part of their work process. However, he started out as a field application engineer for Pfizer's industrial division, developing custom proprietary plastic formulations, and then a launched a design and integration firm focused on custom projects for OEMs. These experiences led to the developments and insights for 3D-printed moldmaking listed below. Design. Zollo believes that the next major obstacle to broader adoption of 3D-printed molds is overcoming the lack of know-how in designing these molds. Print- ed plastic molds differ from metal molds in their surface energy, mechanical strength and heat conductance, Zollo says, and these differences must be accounted for when designing the mold. "Here's a simple example: Increase the draft of internal pins and structures to ensure smooth movement between mold halves. If 3 percent draft was specified in the CAD drawing for metal molds, revise this to 4 to 5 percent for printed plastic molds," Zollo says. Holes should be printed slightly smaller in diameter, so they can be post - pr ocessed to smooth the interior. A few other examples of principles that need to be learned and applied include how to adapt the infill and outer layer print strategy to optimize mechanical strength; how to orient the print job for optimal parting lines; how to properly dimension holes for alignment and knock-out pins; and how to properly design printed-in cooling channels. Materials. "Engineers designing a part usually begin with mechanical and other physical characteristics and then select their material based on these requirements. For me, it seemed logical to start with the mechanical and chemical properties required Democratizing 3D Printing of Injection Molds By Christina M. Fuges

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