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As for the limitations of RP/AM, Gannon notes, "Our biggest challenge has been extending the materials we can process to include some of the more highly engineered types we run in molding. However, we have grown from this challenge to go above and beyond the materials offered by Stratasys and helped develop new materials." In fact, rp+m received an Ohio Third Frontier Grant in conjunction with the Univ. of Dayton Research Institute, PolyOne Corp., Stratasys, and GE Aviation to continue developing new materials for AM. Whether or not a part is suitable for for AM includes part size, quantity, quality required, timeline, and material requirements. "Unfortunately, there is no easy formula to make that determination. If a customer comes to us for molding low quantities, we always do an analysis on whether RP/AM or injection molding will be more economical for them," explains Gannon. Meanwhile, Thogus is quite intent on growing its AM capabilities. Says Foster, "In the future, we see ourselves having more AM machines than injection molding presses. As a strategic partner in NAMII (National Additive Manufacturing Innovation Institute), we are excited to be a part of new processes and materials that are developed in the future." Currier PlastiCs Coming to appreciate the value of in-house RP took barely any time at Currier Plastics (currierplastics.com). Last April, it acquired an Objet30 desktop 3D printer, which can make prototypes with materials that simulate ABS and PP. According to Max Leone, v.p. of business development, a key driver behind that purchase was the frm's growing use of external RP services. Lead times with service bureaus was always an issue, and there were a lot of variables, such as fnishing, that could not be controlled. Lastly, one of their external sources that had Rapid-Prototyping, AdditiveManufacturing Methods RP processes, all of which can quickly turn 3D CAD fles into physical parts or assemblies, are "additive" in that geometry is formed in thin layers derived directly from CAD fles that are automatically "sliced." This procedure allows creation of complicated internal features, details, and assemblies that would be nearly impossible with other means. Different systems vary primarily by how, and in what form, they deposit and cure the material. •Stereolithography (SLA): Layers are built up from liquid photopolymer that is light-cured before the next layer is applied. •Selective Laser Sintering (SLS): Lasers fuse each layer of powdered material. •Fused Deposition Modeling (FDM): A thin thermoplastic thread is deposited in layers by an x-y moving head. •Digital inkjet-style 3D printers: Print heads dispense droplets of material—a liquid photopolymer or a resinbased liquid binder—in layers that are cured or consolidated by a laser beam or UV lamp. The Connex line of multi-material 3D printers from Objet (now part of Stratasys) are the only models so far that simultaneously jet two materials that simulate thermoplastics. Continued on p. 44... Plastics technology February 2013 33