The shrinkage of the injection molding parts of the in mold injection molding processing factory also depends on the direction of the plastic flow. The plastic is injected into the mold through the gate, and the molecular direction is consistent with the flow direction of the plastic. If there is enough energy to let the molecules return to the loose state, the molecules will return to the non oriented equilibrium state. Injecting general plastic molecules, limiting the filling and filling and pressure protection, is inconsistent with the plastic shrinkage perpendicular to the flow direction. Because of the high shrinkage of crystalline materials, this effect is more obvious for crystalline materials. The shrinkage of amorphous materials varies with the flow direction, but the difference is not obvious. The major material manufacturers have done a lot of experiments on shrinkage, and found that shrinkage is related to many parameters, so it is difficult to accurately predict the shrinkage of materials. Some materials will publish the shrinkage rate under different commodity thickness. However, as mentioned earlier, in thicker molds, because the internal heat of the plastic can remain relatively longer, it will lead to more shrinkage. Therefore, it is difficult to obtain accurate finished product dimensions by accurately customizing mold cavity specifications by injection molding manufacturers