Jackson Machinery Inc. has built its first all-electric blow molding machine a fully automated press with servo-driven parison programming to run silicone gum rubber.
President Robert Jackson said the ElecroMatic SCR-1 has several innovations.
``The art form is the combination of parison programming, automation and the fact that it's fully electric. You could conceivably run it in a clean room because it's electric,'' Jackson said in an interview at the machinery maker's Port Washington headquarters.
Jackson Machinery shipped the first-ever ElectroMatic, a press with 5 tons of clamping force, to a customer in early October. Robert Jackson declined to identify the customer or the end-market application.
Before molding, silicone gum rubber has the consistency of chewing gum.
Hollow silicone parts have been made by blow molding as well as injection molding, but Jackson said there are drawbacks. With blow molding, it is difficult to mold parts with a uniform wall thickness.
Injection molding can make uniform hollow parts from liquid silicone rubber, but it requires a mandrel inside of the mold, and the finished parts must be stripped off the mandrel by hand, he said.
The ElectroMatic solves both problems. All machinery functions are powered by servo-electric motors except for one: When the clamp closes and is locked up, a pneumatic membrane inflates to build the clamping-force tonnage. The bladderlike membrane is located beneath a capture plate and the platen of the machine.
Jackson explained the molding process. The gum rubber is loaded into canisters on the press. A plunger assembly pushes the rubber into the screw, which conveys the material forward to the extrusion head that forms the parison.
``The head is servo-driven and has an infinite number of settings, so now I can vary the wall thickness of the part,'' Jackson said. Parison programming allows the parison to be thinned out, or made thicker, in different sections to correspond to contours or curves in the mold. The final part has very precise walls, without flash which wastes costly silicone material.
The ElectroMatic uses a parison leader rod to keep the part from sticking to either side of the mold during removal by a robot, eliminating reject parts. After the robot grabs the part, the leader rod withdraws and the robot moves the part to a conveyor.
``It's full automatic, with no operator,'' Jackson said. In traditional silicone blow molding, an operator would pull out the parts, which could tear again, creating a bad part.
Jeff Krueger, Jackson Machinery's vice president of engineering, developed another innovation, a device for centering the parison from outside the molding machine. There is no need for loosening or tightening any nuts, or getting inside the press.
``We're able to give you a uniform-wall, hollow part without any labor. The labor savings is the real issue,'' Jackson said.