The Procedures of Injection Mold Manufacturing
Procedures of Injection Mold Manufacturing
The mold is one of the important parts in the injection molding industry, it responds the product shape. For the mold manufacturing, there are several step in general:
1. 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 it’s necessary to negotiate with the product designer carefully. Discuss about the geometric shape, dimensional accuracy and appearance requirements of the product, necessary discussions. And try to avoid unnecessary complexity in mold manufacturing.
2. Mold structure design
A set of high-quality molds requires not only good processing equipment and skilled mold manufacturing workers, but also a good mold design. Especially for complex molds, the quality of the mold design accounts for over 80% of the mold quality.
To achieve this, we must not only fully digest the customer’s requirements, but also 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, we should do the following things:
(1) Understand every detail in the design of each mold, and the purpose of each part in the mold.
(2) When designing, refer to previous similar designs. Besides, 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) Go in the factory, know about the process of processed products. Also, recognize the characteristics and limitations of each process.
(5) Know about the results of mold trial and mold modification of the mold designed by yourself.
(6) In the design, try to adopt the previous successful mold structure.
(7) Know more about the impact of cooling system in the mold on products.
3. Determine the mold material and select standard parts
In the selection of mold materials, we should consider the accuracy and quality of the product. Besides, It is also necessary to combine the actual processing and heat treatment capabilities of the mold factory to make the correct choice. In addition, in order to shorten the manufacturing cycle, use existing standard parts as much as possible.
4. Parts processing and mold assembly
Except for the best structure and reasonable tolerance fit in the design, the mold accuracy 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.
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, the cavity, core and other key parts should be quenched in molds with high processing accuracy and large product output. In the medium and large molds, to save materials, facilitate processing and heat treatment, the mosaic structure should be adopted in the mold design.
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, its purpose is to leave a larger adjustment room for the subsequent molding process. It’s for solving the error caused by the molding process.
5. Try out the mold
A set of molds only completes 70% to 80% of the entire manufacturing process from design to assembly. The following points must be tested by mold trial:
- The error caused by the inconsistency between the predetermined shrinkage and the actual shrinkage.
- Whether the demolding is smooth or no.
- How the cooling effect is, especially the influence of the size, position, and shape of the mold gate on the accuracy.
- Appearance of the product.