Researchers at the Univ. of Ontario Institute of Technology (UOIT), Oshawa, Ont., are combining extrusion with rotational molding to speed production of foam-core parts with a solid skin.
Researchers at the Univ. of Ontario Institute of Technology (UOIT), Oshawa, Ont., are combining extrusion with rotational molding to speed production of foam-core parts with a solid skin. Professor Remon Pop-Iliev’s new technique was presented at the 2008 SPE ANTEC conference in Milwaukee. The first step is to melt nonfoaming PE powder in a biaxially rotating mold to form the solid skin. Then, extruded melt with chemical blowing agent is injected through the skin while still soft. The extruder die is mated to an injection molding shutoff nozzle, which penetrates the mold wall through the center of a so-called “pizza valve” (see illustration) —which makes a selfhealing opening in the skin. The mold is then rotated uniaxially to distribute the core material, moved into an oven, and rotated biaxially to foam the core. Cell morphology is said to be good, because the skin insulates the foam core from direct contact with the hot mold. UOIT is looking for industrial partners to scale up this extrusion-assisted rotomolding process. (905) 721-8668 ext. 2523 • www.uoit.ca