Polyimide; Tecasint® and Vespel®

Ensinger’s Tecasint® family and DuPont’s Vespel® family of high-performance polyimide resins out perform most engineering thermoplastics in thermally aggressive bearing and seal applications. With or without lubrication these materials function over a wide range of temperatures and stresses while retaining outstanding creep strength, abrasion resistance, and compressive strength. Their superior thermal resistance allows them to carry loads at temperatures beyond the reach of most plastic materials and do so while exhibiting extremely low creep.

The extraordinary properties of Tecasint® and Vespel® make them the optimal choice for thermally aggressive applications in the automotive, off-road vehicle, jet engine and semiconductor manufacturing sectors. Polyimides do not become brittle, even at -400° F and have continuous service temperatures approaching 600° F.  Close tolerance machining can be achieved with standard metal-working equipment with experience, however special techniques are employed to achieve extremely close tolerances and surface finishes less than 10 rms. Typical applications include sleeve and flanged bearings, rotary seal rings, wafer guides and carriers, insulators, valve seats, gaskets and thrust washers.

Grades

Bearing Grade Polyimides most commonly used as bearing and wear components are;

Tecasint® 2021, Vespel® SP-21, where 15% graphite by weight is added to the base resin for increased wear resistance and reduced friction in applications such as bearings, thrust washes, bushings, seal rings, slide blocks and other wear surfaces. These have the highest mechanical properties of the graphite-filled grades.

Tecasint® 2031, Vespel® SP-22, where 40% graphite by weight is added to the base resin for enhanced resistance to wear and friction and good dimensional and oxidative stability. These have the lowest coefficient of thermal expansion of the graphite-filled grades.

Vespel® SP-211, where 10% Teflon (PTFE) and 15% graphite by weight are added to the base resin for the lowest coefficient of friction over a wide range of operating conditions. Vespel® SP-211 has excellent wear resistance up to 300° F.

Vespel® SP-3, where 15% molybdenum disulfide by weight is added to the base resin for bearing and wear components in vacuum and moisture-free environments.

Tecasint® is a registered trademark of Ensinger, Vespel® is a registered trademark of E.I. Dupont