Die inserts cut cost of thermoplastic pultrusion. (Keeping up with Composites).

Replaceable die inserts allow pultrusion of different numbers and shapes of thermoplastic composite profiles at one-fourth or less of the cost of a whole new die. Dow Plastics, Midland, Mich., filed for patents on these die inserts as an enhancement of its Fulcrum thermoplastic pultrusion technology. "With the same die body, you can make one big part or 10 small ones, just as long as you keep the throughput rate within [+ or -]50%," says Chris Edwards, Fulcrum business development manager. The accompanying photo shows various shapes that can be produced from one die body with different inserts.

The insert is a thick steel plate that shapes and cools the molten composite at the exit end of the die. Inserts can be fabricated in a few weeks or less instead of months for a typical die. The automatically self-centering inserts also can be changed in a few hours and weigh just 1 lb or less. "You could make three different profiles in one day," says Edwards.

The Fulcrum process utilizes Dow's high-modulus engineering thermoplastic polyurethane (ETPU). Edwards says it produces higher mechanical properties than are obtainable with thermosets or other thermoplastics because the highly polar TPU bonds very well to the glass fibers. Fulcrum composites can be easily post-formed by heating and scrap can be reused for injection molding. Tel: [phone], www.dowfulcrum.com