Plastic products, and the molding process is highly automated, and has a wide range of applications in plastic molding. However, with the increasing use of plastic products, people have put forward higher requirements on the precision, shape, function and cost of plastic products. The traditional injection molding process has been difficult to adapt to this requirement. The main performances are as follows:
(1) When producing large-area structural parts, high melt viscosity requires high injection pressure, and high injection pressure requires large clamping force, thereby increasing the cost of the machine and the mold;
(2) When producing thick-walled parts, it is difficult to avoid surface shrinkage and internal shrinkage, and the dimensional accuracy of plastic parts is poor;
(3) When the composite fiber is added to the composite material, the fiber orientation control ability is lacking, and the fiber distribution in the matrix is random, and the reinforcing effect cannot be fully exerted.
Therefore, on the basis of the traditional injection molding technology, some new injection molding processes, such as gas-assisted injection, shear-controlled orientation injection, layer injection, core injection, low-pressure injection, etc., have been developed to meet the needs of different application fields.