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ABOUT THE AUTHOR: Jim Fattori is a third-generation injection molder with more than 40 years of molding experience. He is the founder of Injection Mold Consulting LLC, and is also a project engineer for a large, multi-plant molder in New Jersey. Contact jim@injectionmoldconsulting.com; injectionmoldconsulting.com. away from the gate. If the pin cannot be relocated closer to the gate, due to a water line or some other obstruction, ribs can be added to stiffen the runner and reduce the flexing. Stiffening ribs can be added to either side of the parting line, or in severe cases, both sides. Deciding where to locate the short- ened ejector pin so that the runner isn't too stiff or too flexible is no easy task. And if the mold has to run more than one type of material, it makes the decision that much harder. One option is to add a second—interchangeable—shortened ejector pin, closer to or farther away from the gate than the existing pin. This gives you the ability to use one pin for one material, and a second pin for a second material. Got flakes? Last month I touched on how flakes are formed at the tip of any type of tunnel gate, with elliptical tunnel gates being the worst offender. If you are fighting a flaking issue, one of the best solutions is to convert the elliptical gate to a chisel gate. The tunnel gate pictured on p. 52 is one I modified for a part made of 45% glass-filled nylon 66. You can still see where the elliptical gate used to be. The flaking stopped immediately, and the processing window widened. An ugly tunnel-gate scar is often caused by more than just one problem. www.sepro-america.com • info@sepro-america.com 412-459-0450 • @SeproGroup At NPE 2018 The Future is Next Generation Robots and Controls Innovation Integration Collaboration Choice Look for us in Hall E, Booth W8571 @plastechmag 55 Plastics Technology T O O L I N G