Here, the injection time of the injection time is the time required for the cavity filled with plastic melt, excluding mold opening, closing and other auxiliary time. Despite the injection time is very short, the molding cycle of too little plastic injection, but adjust the injection time of the gate, runner and cavity pressure control has a significant role. Injection reasonable time to help melt the ideal filling, and for improving the surface quality of the products and reduce the size of tolerance has very important significance. Injection time is much less than the cooling time, about 1/10 to 1/15 of the cooling time, this rule can be as a predictor of all plastic parts molding time basis. In making mold flow analysis, only the case where the melt is entirely driven by the rotation of the screw cavity filled, the results of the injection time to set equal conditions injection time. If the screw holding pressure switching occurs before the cavity is filled, then the results of the analysis will be more than a set of process conditions. 1, in the form of molding shrinkage Molding shrinkage mainly in the following aspects: (1) line of plastic parts dimensional shrinkage due to the thermal expansion and contraction, elastic recovery when releasing the plastic parts, plastic deformation causes the release of plastic parts cooled room temperature shrink its size, it must be considered to be compensated for this cavity design. (2) contraction in the direction of molecular orientation during molding are arranged so that the plastic parts exhibit anisotropy along the material flow direction (i.e., parallel to the direction of) the shrinkage, high strength, and the stream direction perpendicular (i.e., vertical direction) is small contraction Low intensity. In addition, since the plastic parts forming the various parts of the packing density and uneven distribution, it is also uneven shrinkage. Shrinkage errand plastic parts prone to warping, deformation, cracks, especially in the extrusion and injection molding is more obvious directionality. Therefore, plastic injection factory, mold design should be considered directional shrinkage of plastic parts according to the shape of the material flow direction shrinkage rate should be chosen. (3) shrink plastic molding, due to the molding pressure, shear stress, anisotropy, density unevenness, uneven distribution of filler, mold temperature unevenness, uneven hardening, plastic deformation and other factors plastic injection plant, causing a series of stress, not all disappear when the viscous flow state, so plastic parts under stress state residual stress during molding. After releasing the stress tends to affect the balance and storage conditions, residual stress changes after leaving the plastic shrink shrink again called. General plastic parts within 10 hours after releasing the biggest change, the basic shape 24 hours, but finally stabilized to 30-60 days. Contraction than usual thermoplastics thermosetting, large extrusion and injection molding of plastic than the pressure molding. (4) post-treatment is sometimes shrink plastic parts according to the performance and process requirements, the need for post-forming heat treatment, post-treatment can also cause changes in the size of plastic parts. So the high-precision plastic parts should be considered after shrinkage and post-processing error and compensate contraction mold design. Plastic injection Suppliers | integration into a plastic mold manufacturers (certified) | plastic injection into harmony by the Shenzhen Municipal Science and Technology Limited. Shenzhen harmony Technology Limited (www.rhctech.net) Guangdong Shenzhen, plastic products leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. The integration into a plastic mold factory leadership with the staff warmly welcome all inquiries negotiations to create harmony into a plastic mold manufacturers a better future.