ROSEVILLE, Calif. (Nov. 29)—Performance Polymer Technologies L.L.C. is purchasing six new presses, adding two shifts and increasing its work force by about 25 percent to keep pace with a surge in customer demand. PPT, which recently moved to a 40,000-sq.-ft. plant in Roseville from a 26,000-sq.-ft. facility in Sunnyvale, Calif., also is contemplating another expansion sometime in 2001 if business continues to increase. The company is adding six compression molders to handle a wide variety of products, primarily for the semiconductor, food and beverage, and instrumentation industries, President Lonnie J. Wimberly said. The new machines will cost the firm between $300,000 and $350,000, he figures. The custom parts molder and silicone goods manufacturer has added second and third shifts and is padding its employee ranks by between 18 to 25 people to help handle the increased capacity, Wimberly said. That would give the firm about 60 workers.