The plastic molding process of the environment friendly plastic cooler box will have a volume change due to crystallization, a strong internal stress, a large residual stress frozen in the plastic part, and a strong molecular orientation, so that it is compared with the thermosetting plastic. The shrinkage rate is large, the shrinkage rate range is wide, the directivity is obvious, and the shrinkage after shrinkage, annealing or humidity control after molding is generally larger than that of the thermosetting plastic.
The plastic parts of the environment friendly plastic cooler box are formed into direct contact with the surface of the cavity and the surface of the cavity to form a low-density solid casing. Due to the poor thermal conductivity of the plastic, the inner layer of the plastic part is slowly cooled to form a high-density solid layer with a large shrinkage. Therefore, the wall thickness, the slow cooling, and the high density layer thickness are large. In addition, the presence or absence of inserts and insert layouts and quantities directly affect the flow direction, density distribution and shrinkage resistance, so the characteristics of the plastic parts have a great influence on the shrinkage size and directionality.
The form, size and distribution of the feed port of the environmentally-friendly plastic cooling box will directly affect the direction of the flow, the density distribution, the pressure-preserving and shrinking action and the molding time. The direct feed port and the feed port have a large cross section (especially thicker cross section), but the shrinkage is small but the directivity is large, and the feed port width and the short length are small. The shrinkage is large near the feed port or parallel to the flow direction.