Analysis of the five major steps in the production process of injection molds

First, the process analysis of plastic products

Before the mold design, the designer should fully analyze whether the plastic products meet the injection molding processing principle, and need to negotiate with the designer of the product, and a consensus has been reached. These include the geometry, dimensional accuracy and appearance requirements of the product, and the necessary discussion to avoid unnecessary cumbersome manufacturing.

Second, the mold structure design

A set of high-quality molds not only requires good processing equipment and skilled mold making workers, but another very important factor is to have good mold design, especially for complex molds. The mold design is good or bad. %the above. An excellent mold design is: under the premise of meeting the requirements of customers, the processing cost is low, the processing difficulty is small, and the processing time is short. To do this, we must not only fully digest the requirements of the guests, but also have an understanding of the injection molding machine, the mold structure, the processing technology and the processing capabilities of the mold factory itself. Therefore, to improve the mold design level, the following should be done:

1. Understand every detail in each mold design and understand the purpose of each part in the mold.

2. In the design, refer to the previous similar design, 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. The factory understands the process of processed products and recognizes the characteristics and limitations of each process.

5. Understand the test results and mold changes of the molds you designed, and learn the lesson.

6. Try to use the previously successful mold structure when designing.

7. Learn more about the effects of mold water on the product.

8. Study some special mold structures and learn about the latest mold technology.

Third, determine the mold material and select standard parts

When selecting mold materials, in addition to the accuracy and quality of the product, it is necessary to give the correct choice in combination with the actual ability of the mold factory for processing and heat treatment. In addition, in order to shorten the manufacturing cycle, the existing standard parts are utilized as much as possible.

Fourth, parts processing and mold assembly

In addition to the optimum structure and reasonable tolerances in the design of the mold, part machining and mold assembly are critical. Therefore, the selection of machining accuracy and processing methods is absolutely dominant in mold manufacturing. The dimensional error of a molded product 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 the molded part is about 1/3

4. The error caused by the inconsistent predetermined shrinkage and actual shrinkage is about 1/6.

Total error = (1) + (2) + (3) + (4)

Therefore, in order to reduce the mold manufacturing error, 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 the error caused by the wear and deformation of the mold, in the mold with high processing precision and large product output, the key parts such as the cavity and the core should be quenched. In medium and large molds, in order to save materials and facilitate processing and heat treatment, the mold should be designed with a mosaic structure. In order to solve the error caused by the uneven shrinkage of the molded part and the inconsistency between the predetermined shrinkage and the actual shrinkage, one third of the tolerance of the product is generally selected in the manufacture of the mold, and the purpose of the manufacturing tolerance of the mold is to give a later molding process. Large adjustment room to solve the error caused by the molding process.

Five, try

A set of molds is designed from the beginning to the end of assembly, but only 70% to 80% of its entire manufacturing process. For the error caused by the inconsistency between the predetermined shrinkage and the actual shrinkage, the smoothness of the demoulding, and the cooling effect, especially the influence of the size, position and shape of the gate on the accuracy and appearance of the product, must be tested by trial mode. Therefore, the test mode is an indispensable step in verifying the conformity of the mold and selecting the optimum molding process.