A reciprocating cycle process of the central feeding system feeding after injection molding, each injection cycle mainly includes: the first dosing - melting - pressure injection die cooling - the final modepickup. After the workers remove the plastic parts and automatically close the mold, the next cycle. The working principle of the syringe with injections of each injection molding machine used is very similar, it is the use of screw (or piston) thrust, the plasticizing good solution (i.e., viscous) plastic injection into the closed sealed cavity, the fixed cooling process after obtaining products. The central feeding system of such enterprises after years of development, has a stable and reliable strength, compared to the international big enterprise products, the central feeding system, mainly in the price of plastic products, the price is low, to a wider range of domestic enterprises into the bear range; and the plastic machinery equipment export has become a priority among priorities. In the face of the development of plastic machinery industry, China's plastic packaging machinery enterprises should seize the opportunity.