... polypropylene plastic ball is mainly used in cars, sensor, valves, pumps, valves, bathroom, electronic, bearing, electric appliances, and other industries ... resistance to creep and stress ability, excellent wear resistance, self-lubricity, fatigue sex, high density and high crystalloid linear ... of + / - 0.02 to 0.001 mm, without closing parting line, without burr, smooth surface, high technology, high ...