DuPont Engineering Polymers has debuted fast-cycling polybutylene terephthalate for injection molding.
Crastin SF grades can cut cycle time by up to 30 percent and costs by up to 20 percent, the Wilmington, Del., company claims. They are particularly well-suited to make thin-wall parts such as connectors and large parts like structural housings.
Fast cycling is due to the resin's exceptionally high flow, DuPont explains. A 30 percent glass-filled grade has melt viscosity that is 43 percent lower than a standard grade at 482° F, according to the company. High flow can translate into major reductions in melt temperature, saving time during pressure hold and cooling. High flow also can lead to thinner walls and more intricate flow paths as well as greater mold cavitation.
Mechanical properties of the new materials are comparable to standard PBT grades. DuPont offers Crastin SF in 30 percent glass-filled, 15 percent filled and unfilled versions.