Full definition
An additional heat treatment applied to vulcanized rubber parts after demolding, in a hot-air oven without pressure, to complete the cross-linking reaction, drive off volatile decomposition by-products, and stabilize the final properties. Essential for: FKM/Viton (4-24 hours at 200-250°C — without post-cure, compression set is 3-5x worse and parts emit corrosive HF vapors), FFKM/Kalrez (up to 24 hours at 250-315°C depending on grade), silicone VMQ (2-4 hours at 200°C to volatilize peroxide decomposition products and improve compression set), and peroxide-cured EPDM (2-4 hours at 150-175°C for optimal compression set). Post-cure typically reduces compression set by 30-50% and stabilizes hardness within ±2 points of specification. Parts must be supported on a rack (not touching) for uniform heat circulation. Oven temperature uniformity: ±5°C. Ramp rate: gradual heating to avoid thermal shock in thick sections. Omitting post-cure is a common quality failure in cost-driven manufacturing.