Since Ryton® PPS will flex very little during ejection, part designs should avoid undercuts and provide sufficient draft to eject the part without flexure.
Short cores and shallow cavities of 0.2 inch (5 mm) or less should have at least 0.25° of draft per side. As cavity depth and core length increase to one or two inches (25 to 51 mm), the draft angle should increase up to 2° per side. To improve release, cores and cavities should be polished to a 4 microinch (0.0001 mm) finish or better. Polish marks should be parallel to the direction of part ejection (commonly referred to as draw polishing).
In special cases, an undercut can be useful to retain parts on the core or cavity during mold opening. The interference should range from 0.0005 to 0.001 inch (0.013 to 0.025 mm). Since Ryton® PPS compounds are very stiff, any undercut areas in a mold will experience high wear rates and the undercut will likely be sheared off (rather than flex) upon part ejection.
