Development of a mixing screw for painted TPO bumper regrind

The recycleability of automotive bumpers is complicated by the fact that the paint particles act as contaminants in the recycle and translate into surface defects on the bumper. Reducing the paint particle size will help eliminate this problem.; The goal of this project was to develop a plasticating screw design that will break down the paint particles below a size of 1.5 mm. To accomplish this objective a Maddock and a tensile flow mixing section were designed, fabricated, and tested.; The results indicated that tensile mixing screw performed better than the conventional mixing screw and in some cases the Maddock mixing screw, in breaking down the paint particles below a size of 1.5 mm.