Process analysis of plastic products.
Before the mold design, the designer should fully analyze and study whether the plastic product conforms to the injection molding processing principle, and needs to negotiate with the product designer carefully, and a consensus has been reached. Including the geometric shape, dimensional accuracy and appearance requirements of the product, necessary discussions, try to avoid unnecessary complexity in mold manufacturing.

Mould structure design.
A set of high-quality molds requires not only good processing equipment and skilled mold manufacturing workers, but also a very important factor is to have a good mold design. Especially for complex molds, the quality of the mold design accounts for 80% of the mold quality. %the above. An excellent mold design is: on the premise of meeting the requirements of the customers, the processing cost is low, the processing difficulty is small, and the processing time is short.
To do this, it is necessary not only to fully digest the customer’s requirements, but also to have an understanding of the injection molding machine, mold structure, processing technology, and the mold factory’s own processing capabilities. Therefore, to improve the level of mold design, the following points should be achieved:
1. Understand every detail in the design of each mold and understand the purpose of each part in the mold.
2. When designing, refer to previous similar designs, and understand the situation in its mold processing and product production, and learn from the experience and lessons.
3. Learn more about the working process of the injection molding machine to deepen the relationship between the mold and the injection molding machine.
4. Under the factory, understand the process of processed products, and recognize the characteristics and limitations of each process.
5. Understand the results of mold trial and mold modification of the mold designed by yourself, and learn lessons.
6. In the design, try to use the more successful mold structure before.
7. Learn more about the impact of mold water on products.
8. Study some special mold structures and understand the latest mold technology.

Determine the mold material and select standard parts.
In the selection of mold materials, in addition to considering the accuracy and quality of the product, it is also necessary to combine the actual processing and heat treatment capabilities of the mold factory to give the correct choice. In addition, in order to shorten the manufacturing cycle, use existing standard parts as much as possible.

The mold steel grades commonly used is 2344/718, and its hardness is about 36HRC.

Parts processing and mold assembly.
Except for the best structure and reasonable tolerance fit in the design, the precision of the mold is very important for parts processing and mold assembly. Therefore, the choice of processing accuracy and processing method occupies an absolute dominant position in mold manufacturing.
The dimensional error of molded products is mainly composed of the following parts:
1. The manufacturing error of the mold is about 1/3
2. The error caused by mold wear is about 1/6
3. The error caused by uneven shrinkage of molded parts is about 1/3
4. The error caused by the inconsistency between the scheduled contraction and the actual contraction is about 1/6
Total error = (1) + (2) + (3) + (4)
Therefore, in order to reduce mold manufacturing errors, the machining accuracy should be improved first. With the use of CNC machine tools, this problem has been well controlled. In addition, in order to prevent errors caused by mold wear and deformation, when molds with high machining accuracy and large product output are required, the key parts such as the cavity and core should be quenched. In the medium and large molds, in order to save materials and facilitate processing and heat treatment, the mosaic structure should be adopted as much as possible in the mold design.
In order to solve the error caused by uneven shrinkage of the molded part and the inconsistency between the predetermined shrinkage and the actual shrinkage, 1/3 of the product tolerance is generally selected during mold manufacturing as the manufacturing tolerance of the mold, and the purpose is to leave a relatively large margin for the subsequent molding process. Large adjustment room to solve the errors caused by the molding process.

Trial mold.
A set of molds only completes 70% to 80% of the entire manufacturing process from design to assembly. The error caused by the inconsistency between the predetermined shrinkage and the actual shrinkage, whether the demolding is smooth or not, how the cooling effect is, especially the influence of the size, position, and shape of the gate on the accuracy and appearance of the product, must be tested by mold trial. Therefore, mold trial is an indispensable step to check whether the mold is qualified and select the best molding process.