Injection molding is to mold molten plastic into a closed mold with a lower temperature through a nozzle under high pressure. Both thermoplastics and thermosetting plastics can be injection molded. In the production of packaging containers, it can mainly produce various box-type packaging containers, such as various turnover boxes and small boxes. For box-type packaging containers, the following aspects should be considered in structural design. Wall thickness of container The design of wall thickness mainly considers three aspects: one is thickness; the other is uniformity; the third is smooth transition. Thickness: The wall thickness of the container is mainly determined by its use, type of plastic, structure, etc. For thermoplastics, it should not be less than 0.6mm, usually 2 ~ 4mm. For thermosetting plastics, because of its poor fluidity, the thickness should be larger, 1.6 ~ 2.5ram for small parts and 3.2 for large parts 8mm, the maximum does not exceed 10mm. Uniformity: The uniformity of the wall thickness has a great influence on the quality of the container. If the thickness difference of a container is too large, it will cause uneven shrinkage and cause defects such as deformation and cracks. Therefore, the structure should be designed with equal thickness as much as possible. Gently transition: In some containers, some parts must have different thicknesses due to structural requirements, such as the corners of the container. At this time, a gentle transition should be used to avoid sudden cross-sections. 2. Increase stiffness Plastic is relatively flexible, and the rigidity of the container made is poor, and the turnover box container sometimes has a large load capacity. Therefore, various structural measures should be taken to improve the rigidity.