Blow molding mainly refers to a method in which hollow blow molding is a method of inflating a hot-melt parison closed in a mold to form a hollow product by means of gas pressure, and is a plastic forming method which is developed rapidly. Blow molded products are designed according to the requirements of use. In the design, we must first consider the advantages of the plastic material to avoid the shortcomings. Under the premise of meeting the requirements of use, the shape and structure of the blow molding should be as simple as possible to simplify the mold structure and meet the process characteristics.

1. Formability of plastic materials, such as fluidity (melt flow rate, viscosity).

2. physical and mechanical properties of plastic materials, such as strength, rigidity, toughness and so on.

3. the shape of the blow molding should be conducive to filling flow, exhaust, feeding, and at the same time can adapt to efficient cooling and shaping.

4. the sanitary properties of plastic materials, such as whether it meets the requirements of food packaging, pharmaceutical packaging.

5. the overall structure of the mold, especially the complex program of the mold clamping device and plastic parts demoulding.

6. Structural design and manufacturing process of mold parts.

7. The difference between the molding shrinkage and the shrinkage ratio of the blow molded parts.