First, we must look at the structural complexity of this mold. Generally speaking, it takes about a month to open a pair of injection moulds. Complex molds take longer time. Usually an injection mold is opened. It is necessary to have a detailed examination. After approval, the mold can be opened. After opening the injection mold, the mold needs to be tested. Injection molds need to manufacture the following items:

1. The cooling (water passage) in the mould is related to the size, shape, plasticity and holding time of the product.

2. The roughness of the die cavity should reach the "mirror level", otherwise the product is difficult to demould, and the product needs too much power when it pops up. The roughness of the locating pin, clamping surface and other parts is standard.

3. The plastic mold should have enough rigidity, otherwise it will deform when the mold is kept under pressure, which will lead to the selection of reasonable exhaust position and its control quantity. Otherwise, the plastic is not filled and the product is "missing".

4. The injection molding road should be reasonably selected so that the material evenly reaches each place (equal flow path), and there must be sufficient storage space to ensure that the plastic is added during shrinkage. Moreover, the shrinkage coefficient of each material is different, and the die has a reasonable shrinkage.

5. The fixing mode of the mold and the injection molding machine should be reasonable, reliable and firm, so as to prevent the accident caused by the displacement when the mold is closed. Disassembly is also very convenient. In addition, it is necessary to select a reasonable demoulding method, and choose the appropriate location and quantity of ejector pin to ensure that the product is not damaged during the ejection process.