Oak Brook, Ill. — Injection molding simulation is being widely used to design parts and molds, and the technology is becoming ever-more powerful, speakers said at IMTECH.
Doug McMullen, technical sales of DatapointLabs, said the company runs a test laboratory where it characterizes materials, which he said lets injection molders get better simulation.
"The questions we are trying to answer about materials and molding are very complex," McMullen said. DatapointLabs is located in the Cornell Business and Technology Park in Ithaca, N.Y.
Ken Cheng, an engineer at Core Tech Systems Co. Ltd., said simulation helps build complex parts very quickly, belying the common idea that a 3D mesh takes forever to build a simulated part.
"You can use simulation to give you a virtual model," said Cheng, whose company makes Moldex3D simulation software.
Cheng told how molding simulation can predict warpage, in a presentation at IMTECH in Oak Brook. The Injection Molding Division of the Society of Plastics Engineers organized the first-ever IMTECH to give technical information to engineers.
Cheng said viscoelasticity plays a very important role in warpage, and his company's software has enhanced warpage analysis capabilities. The cooling rate also is critical, he said, adding that stress increases with a longer cooling time.
Moldex3D designers want to capture a good resolution of the runner. 3D mesh lets them capture a good temperature resolution, Cheng said.
Mark Yaeger, field engineering manager for Covestro LLC, looked at stresses and their effects on the durability of molded parts. He focused on polycarbonate, using the analogy of a spring: the material gets stretched out, which results in molded-in stress, he said.
Typically, simulation shows flow stresses at the gate, shrinkage stress around holes, flow shrinkage in thin walls, and problems at corners, Yaeger said.
He described the results of tests done by Covestro on the impact of stress on polycarbonate. What influences injection molding of molding of PC? Yaeger said: Melt temperature, the effect of filling speed and mold temperature, and insert molding.
