In view of the uneven or unreasonable thickness of the plastic injection chair mold structure, it is not only easy to cause uneven force and strain of the mold, but also easy to cause different thermal and organizational stresses between the various parts of the mold due to heating, so that the volume expansion of each part is different. Therefore, when designing an injection mold, the thickness gap between the mold should be minimized, a symmetrical structure should be adopted, and a smooth transition structure design should be adopted at the junction of thickness and thinness. In addition, the elastic deformation of the mold itself and the size of the cavity will affect the accuracy of the mold. In the traditional compression mould design, the cavity size design only mainly considers the moulding shrinkage rate of the product, and generally does not take the mould itself into consideration. The elastic deformation is taken into account. Although simply increasing the mould wall thickness can reduce the mold's own elastic deformation caused by force and heat, the mold size design also needs to consider the mould installation, ease of processing and cost (including processing costs and material costs).
And whether the wall thickness of the chair mold is uniform and manual work on the parting line is a cause of uneven wall thickness. Of course, most of the reasons are caused by the 3D design of the plastic chair and poor lighting of the cavity core. So when we started designing a plastic chair mold, we had to consider the wall thickness. Sometimes, we need to make some areas thicker to ensure the strength of the chair. But at the same time we have to think about this issue carefully. Because the uneven wall thickness will cause uneven injection and uneven cooling. This will slow down the injection speed and at the same time will lead to a miniature. If the CNC milling process is not accurate, it is impossible to make a chair with uniform thickness.