PPS solves creep in metering pumps

Liquid Metronics Inc. resolved cracking and creep issues in two key elements of its redesigned line of electromagnetic chemical metering pumps by switching materials.

In this application, the polyphenylene sulfide (PPS), from Ticona, is pocket-molded as a 1-in. thick, 3-in. diameter insert into a glass-filled polypropylene (PP) block. The old design, one made of an all-polypropylene block, worked well except the PP would creep under the 24-in.-lb. torque load imposed on it by the head bolts — which over time caused it to lose torque and eventually leak. By adding a Fortron 4184L4 PPS (black) insert, it gave twice the rigidity, and a much lower creep.

The parts made from Fortron PPS are molded at 325F in oil-heated molds to gain the proper crystallinity. The molds are packed tightly at high pressure so parts surfaces are flat and have a good finish.

Ticona 908-598-4209