Two engineers and entrepreneurs that were buying plastic parts to manufacture a line of automotive aftermarket air/fuel ratio gauges decided they wanted to mold them in-house, but balked at the cost of conventional injection machines. So they decided to design and build their own. About a year ago, Burak Cevik and Kubi Kara, partners in APSX LLC, Blue Ash (Cincinnati), Ohio, came up with a tabletop machine with 7.5-ton clamp and plunger injection unit capable of 1.83 in.3 (3 to 40 g) shot size and 5000 psi injection pressure. All axes on the machine are driven by servo stepper motors—another product line of APSX. The two partners have been using the press to mold cases and bezels of TPO and PP, but they have also used it with HDPE, PS, ABS, and powdered-metal injection molding (PIM/MIM) compounds. Starting in December, the partners decided to start promoting the machine to inventors, custom molders, and small manufacturers of toys and other products for prototype and short-run production.
The APSX-PIM machine measures 43 in. long x 12 in. wide x 15 in. high and weighs 250 lb. It was designed for simplicity and low cost. It has no air or water connections. Mold cooling is external, applied by a variable-speed, electronically controlled fan mounted over the clamp. The machine has a feed auger to move pellets from the hopper to the injection barrel, which has a 1-in.-diam. plunger instead of a screw. Heater bands on the barrel provide the energy to melt the small shots of resin. APSX’s in-house molding produces a part in about 60 sec.
The four-tiebar clamp is driven by a stepper motor and ballscrew. The injector is driven by a stepper motor pushing against a spring, which pushes against the plunger. A shutoff nozzle opens for injection and closes after mold filling. Max. mold size is 4.8 x 6 in. and clamp stroke is 6 in. The machine costs $12,500, but is available for as little as $6000 to participants in a Kickstarter “crowd-funding” capital-raising campaign starting this month. Machines usually ship in two to six weeks; several units were in stock at press time. A video of the machine in action is available here.