Polyacetal or polyoxymethylene (POM) has a low coefficient of friction, good dimensional stability, and high temperature resistance.
Not required but store the material in a dry atmosphere.
50 C 105 C [122 F 221 F]. Higher mold temperatures are preferred for precision molding to reduce post-molding shrinkage.
70 120 MPa
Medium high
Any type of gate can be used. Use circular tapered gates that are as short as possible. Insulated, hot tip runners are preferred for homopolymers. Both internally and externally heated hot runners can be used with copolymers.
Acetals are tough, resilient materials that exhibit good creep resistance, dimensional stability, and impact resistance even at low temperatures.
Acetal grades are either homopolymers or copolymers. Homopolymers have better tensile strength, fatigue resistance, and hardness, but are difficult to process. Copolymers have better thermal stability, chemical resistance, and processability. Both homopolymers and copolymers are crystalline and have low moisture absorption.
Copolymers can be used continuously at air temperatures up to 100 C [212 F]. Homopolymers have slightly higher temperature resistance. The many grades of acetal materials that are available can be tailored for different applications.
High crystallinity levels of acetals lead to relatively high shrinkage levels of 0.02 0.035 mm/mm. Differential shrinkage is observed with reinforced grades.