When screws are required to assemble critical components, readily available fasteners, such as those made from carbon steel, stainless steel, and nylon, are frequently used based on their convenience and cost. These common screws, however, no longer meet the challenges posed by today's engineers who continue to push the design envelope with higher-performance materials. PERPL Series 7 screws, made from PEEK (polyetheretherketone) polymer in standard UNC sizes, are designed to fill the gap between metallic screws and low-performance nonmetallic screws.
Carbon-steel screws cannot be used in such applications as wastewater treatment, pollution control, chemical processing, or industrial machinery because of corrosion from water or chemicals. In these situations, stainless steel is often considered as an alternative because of its improved corrosion-resistance properties. However, many chemicals, including strong acids and inorganics such as salts, will attack stainless steel.
A second alternative in harsh industrial applications is the non-metallic polymer screw--usually nylon--which has inherent corrosion resistance. However, nylon has limited resistance to harsh chemicals and high temperatures, and a limited ability to withstand high loads.
When compared to nylon screws, high-performance PEEK polymer screws offer superior chemical and corrosion resistance to most strong acids, bases, inorganics, and solvents. In contrast, nylon screws are attacked by strong acids and bases at elevated temperatures, and swell when exposed to some polar solvents, including water and alcohol. PEEK screws also have inherently higher strength and temperature-resistance properties.
Off-the-shelf PERPL Series 7 screws are well suited for use in the semiconductor equipment and manufacturing industries. They offer low outgassing and low particle generation, in addition to their high-strength properties. They are also suited for industries requiring non-metallic screws from the outset, including microwave and radio wave transmission.
To speak with a Performance Plastic Fasteners applications engineer, call (610) 458-2038 or fax (610) 458-2041.