Reducing High Springback in PEEK Seals

A manufacturer of seals for the oil and gas market was having issues with split rings “springing” when they machined parts from large diameter 30% glass-filled polyetheretherketone (PEEK) tubes.

PEEK is preferred in the oil and gas industry for anti-extrusion backup rings, piston and sealing rings, valve seats, electrical connectors and compressor valve plates because of its favorable properties. However, the residual stress introduced during the tube injection molding process can cause machined split rings to “spring” inward or outward. Depending on the degree and direction of the springing, it could make the part unsuitable for the intended sealing application.

Curbell worked with the seal manufacturer to find a better solution to reduce cost by providing a more suitable material option. PEEK was required by the end user specifications, as this material has high thermal and mechanical capacity, chemical resistance, and wear performance. Given the end user specification restraints, Curbell worked closely with the manufacturer to find an alternative shape conversion method that met the major specifications for use in backup split rings.

Alternate Manufacturing Process for PEEK Tube Provides Solution

Unlike injection molded PEEK tubes, spun cast PEEK tubes are manufactured via a proprietary melt spinning process that results in extremely low residual stress and excellent machinability for split ring applications. And, most importantly, it is approved on end user specifications.

The manufacturer was able to considerably reduce scrap rates and regain lost business thanks to more reliable machinability.