Since the 1980s, China’s mold industry has developed rapidly. In 1989, the State Council promulgated the “Decision on the Key Points of Current Industrial Policies”, and listed mold manufacturing as an industry that focuses on supporting technological transformation. Here are the most useful injection molding basics for you.
After many years’ constant development, Chinese rapid injection mold design technology has made great progress. The total industrial output value of the mold industry continued to grow, with an annual growth rate of 13%. The total output value in 2017 has reached 250.99 billion yuan.
At present, China’s total mold production has ranked in the forefront of the world, and there are many mold companies. However, the overall level of mold design and manufacturing is still undeveloped in comparison to Germany and the United States.
The specific performance is that molds with low technical content have been oversupplied, while medium and high-grade molds with high technical content are far from being able to adapt to the needs of national economic development, such as High-end molds such as precision and complex stamping dies and plastic molds, car cover molds, electronic connectors, and other electronic product molds still rely heavily on imports.
Plastic molds are an important part of the mold industry, mainly including injection molding molds, extrusion molds, blow molds, plastic molds, foam molds, etc., of which injection molding molds account for the largest proportion. Plastic molds are widely used in the production of plastic parts for automobiles, medical equipment, home appliances, aerospace, military, and other fields.
According to estimates by China Die & Mould Industry Association, China’s plastic molds account for about 45% of the entire mold industry, with injection molding molds accounting for the largest proportion. With the rapid development of industries such as automobiles, medical equipment, home appliances, and electronic communications, plastic molds have good prospects for development.
Injection molding is a widely used processing method in the processing industry. The production process is easy to realize mechanical automation. The equipment is easy to operate, high in productivity and low in cost. The processed plastic parts are highly consistent, especially suitable for high-volume production conditions.
Plastic molds play an important role in the realization of plastic processing technology to ensure the shape, size, and tolerance of plastic products. High-efficiency and fully automatic equipment is only possible with the plastic molds that are suitable for automated production. The production and renewal of the products are based on mold manufacturing and updating.
Due to the increasing variety and output demand of industrial plastic products and daily-use plastic products, higher and higher requirements for plastic molds have been put forward, so that plastic molds are being continuously developed.
1. Basic requirements for mold manufacturing
- High manufacturing precision, in order to produce qualified products and to exert the efficiency of the mold, the mold design and manufacture must have high precision. The accuracy of the mold is mainly determined by the accuracy requirements of the product and the structure of the mold. In order to ensure the accuracy and quality of the product, the precision of the working part of the mold is usually 2-4 higher than the precision of the product.
- Long service life. Molds are relatively expensive process equipment. In addition to special cases such as small batch production and new product trial production, molds are generally required to have a long service life.
- The manufacturing cycle is short. In order to meet the needs of production and improve the competitiveness of products, it is necessary to shorten the mold manufacturing cycle as much as possible under the premise of ensuring quality.
- Lower cost. The cost of the mold is related to the complexity of the mold structure, the mold material, the manufacturing accuracy requirements, and the processing method. The technician must design and develop the processing technology according to the requirements of the product.
2. Features of mold manufacturing
Because mold manufacturing is difficult, there are many specialties compared to general mechanical manufacturing.
- High manufacturing quality requirements. Mold manufacturing requires not only high processing precision but also good surface quality. In general, the license tolerance of the working part of the mold should be controlled within +-0.01mm, and some even in the micrometer range. The surface after the mold processing is not allowed to have any defects, and the surface roughness Ra of the working portion is required to be less than 0.8 μm.
- The shape is complicated. The working part of the mold is generally a complex surface of two or three dimensions, rather than a simple geometry of general machining.
- The material has a high hardness. The mold is actually equivalent to a mechanical processing tool. Its hardness is relatively high. It is usually made of hardened tool steel or hard alloy. It is often difficult to manufacture with traditional machining tools.
- One-piece production. Usually, only one or two molds are needed to produce a certain product, so mold manufacturing is generally one-piece production. Every time a mold is manufactured, it must start from the design, it takes more than a month or even months to complete, and the design and manufacturing cycle are relatively long.
Also Read: What is Lean Manufacturing (Lean Production)
3. The Mold Manufacturing Process
Divided into the following six stages
- The mold plan is determined, and the product part structure, dimensional accuracy, surface quality requirements, and molding process are analyzed.
- Design of the mold structure, design of the molded part, structural design, system structure (including positioning, guiding, unloading and related parameter setting), that is, the assembly design.
- Processing of blanks for production preparation, molding materials, modules, etc., standard zero, and accessories. According to the design, the CNC machining code is compiled.
- Machining of molded parts, according to the processing procedure, using CNC for forming, hole processing, or using traditional processes such as an electric spark, forming grinding, and the corresponding heat-treatment process.
- Assembly and test mode, according to the mold design requirements, check the dimensional accuracy, positional accuracy and surface roughness of standard parts and molded parts, and test and test according to the assembly process.
- Acceptance and trial use, according to the technical conditions and contract specifications of various types of molds, the mold test parts (punch parts, plastic parts, etc.) and mold performance, working parameters, etc. are inspected, tested, and qualified.
China, the United States, Japan, Germany, South Korea, and Italy are the world’s major producers of injection molds and stamping dies. Among them, China’s mold production value is the highest in the world. In China, people have become more and more aware of the important position of molds in manufacturing.
Recognizing the level of mold technology has become an important indicator to measure the level of manufacturing in a country, and to a large extent determines the quality of products.
Many mold companies attach great importance to technological development, increase investment in technological advancement, and regard technological progress as an important driving force for enterprise development.