Flash is expected. Trim by hand, cryogenic or punch for high volume.

Tightest O-ring tolerance?

Class 5 per AS568: +-0.07mm on ID. Requires precision tool.

P20 for short runs. H13 for production. Chrome plated.

Limited by press platen. Typical 4-50 cavities.

Learn more about rubber molding for your manufacturing sourcing needs in China.

Rubber Compression Molding: Compounds, Mold Design, Curing

Rubber parts production through compression molding.

Rubber Molding

Compression molding is the oldest method for rubber parts. NBR: oil seals, O-rings. EPDM: weather seals, gaskets. Silicone (VMQ): high-temp, medical. FKM (Viton): extreme chemical/high-temp. Mold pre-heat to 150-190C. Cure time 5-20 min depending on section thickness. Draft angle 2-5 degrees for demolding. Shrinkage: 1.5-3% depending on compound.

Rubber	Temp	Hardness	Tensile	Cost/kg
NBR	150-170C	50-90 A	10-20 MPa	$3-5
EPDM	160-175C	40-80 A	8-16 MPa	$2.5-4
Silicone	165-185C	30-80 A	6-12 MPa	$8-15
FKM	170-190C	60-90 A	10-18 MPa	$25-50