1）Process analysis of plastic products.
Before the mold design, the designer should fully analyze and study whether its plastic products are in line with the injection molding processing principle, which requires careful consultation with the designer of the products, and has reached a consensus. This includes the geometry of the product, dimensional accuracy and appearance requirements, the necessary discussion, and try to avoid unnecessary complications in mold manufacturing.
2）Second, the mold structure design.
A set of high quality mold, not only need to have good processing equipment and skilled mold manufacturing workers, another very important factor is to have a good mold design, especially for complex molds, the good or bad mold design accounts for more than 80% of the mold quality. An excellent mold design is: under the premise of meeting the requirements of customers, make the processing cost low, processing difficulty is small, processing time is short. To do this, not only to fully digest the requirements of the customer, but also to understand 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.Figure out every detail in each mold design and understand the purpose of each part in the mold.
2.Refer more to the previous similar design when designing, and understand the situation when it mold processing and product production, learn the experience and lessons learned.
3.Learn more about the working process of injection molding machine to deepen the relationship between mold and injection molding machine.
4.Go down to the factory to understand the process of processed products and recognize the characteristics and limitations of each processing.
5.Understand the results of mold trial and mold change of the mold you designed, and learn the lessons.
6.Try to use the previous more successful mold structure in the design.
7.More understanding of the impact of the mold into the water on the product.
8.Study some special mold structure and understand the latest mold technology.
3）Third, determine the mold material and select standard parts.
In the selection of mold materials, in addition to considering the precision and quality of the product, we must also combine the actual ability of the mold factory's processing and heat treatment to give the right choice. In addition, in order to shorten the manufacturing cycle, the existing standard parts should be used as much as possible.
4）Parts processing and mold assembly.
In addition to the accuracy of the mold given the best structure and reasonable tolerance fit during the design, the parts processing and mold assembly are crucial. Therefore, the choice of processing accuracy and processing method occupies an absolutely dominant position in the mold manufacturing.
The dimensional error of the molded product is mainly composed of the following components.
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 produced by uneven shrinkage of the molded parts is about 1/3
4、The error arising from the inconsistency between scheduled shrinkage and actual shrinkage is about 1/6
Total error = (1)+(2)+(3)+(4)
Therefore, in order to reduce the mold manufacturing errors, the first thing should improve the processing accuracy, with the use of CNC machine tools, this problem has been well controlled. In addition, in order to prevent the mold wear, deformation and error caused by the processing of high precision requirements and product yield of the mold, the cavity, core and other key parts should be quenched treatment. In the medium and large mold, in order to save material and facilitate processing and heat treatment, mold design should be used as far as possible to put together the structure.
In order to solve the error caused by the uneven shrinkage of the molded parts and the inconsistency between the scheduled shrinkage and the actual shrinkage, 1/3 of the product tolerance is generally chosen as the manufacturing tolerance of the mold when the mold is manufactured, the purpose of which is to leave a large adjustment margin for the later molding process to solve the error caused by the molding process.
A set of mold from design to assembly is only 70%~80% of its total manufacturing process. For the error caused by the inconsistency between the intended shrinkage and the actual shrinkage, the smoothness of the mold release, the cooling effect, especially the size, position and shape of the sprue on the precision and appearance of the product, etc., must be tested through mold trials. Therefore, mold test is an indispensable step to check whether the mold is qualified and to choose the best molding process.