In production, the head or hands and feet of a PVC doll often occur and are easily twisted from the neck position where the body is connected. In addition to design and material issues, injection molding issues are also a very important reason. Sometimes in the same set of molds, there are several identical injection molded parts, some twisting, some easy to break. Even if it is the same cavity injection molding parts, there will be sometimes continuous torsion, sometimes easy to break. Therefore, injection molding technology and production control become quite important.

In the production process, it is first necessary to ensure that the melt has sufficient temperature, and the back pressure of the foot and the melt time should be properly applied to make the melt mature and have good fluidity. Otherwise, it is unmelted glue, enough to make the connection easy to break.

Secondly, as long as the product structure allows, try to increase the transition Angle of the connection, preferably R1.0mm or larger, so that when the melt passes through the corner, there will be no vortex caused by the skin. At the same time, increasing the transition fillet prevents stress concentration and increases the tensile strength of the joint.　

The third is to control the injection speed, which is the most critical point. When adjusting the machine, a lower speed must be used so that the molten liquid flows smoothly from the end of the mushroom to the cavities of the head or hands and feet. The crust is caused by a sudden change in volume and vortices as the melt flows from the small end to the large end. Therefore, reducing the injection speed can reduce the energy generated by the vortex. In addition, due to the good transition Angle, the glue can smoothly pass through the connection without creating eddy currents, thus achieving the purpose of eliminating skin.　

However, if you continue to shoot at a slow speed, it will definitely lead to inaccuracies. Therefore, after the glue flows through the joint, the second stage of accelerated injection must be started immediately.　

In addition, in production, there are often many identical injection molded parts in a set of molds. This is usually the case, and another problem is caused by inconsistent injection rates for each cavity. Therefore, when producing several identical injection parts in the same set of molds, the injection speed of each cavity must be adjusted to achieve balance, to ensure that the injection speed and starting point of each cavity can be consistent, so as to achieve the purpose of eliminating skin at the same time.