Current situation and development direction of plastic mold industry

Since the 1980s, with the support and guidance of national industrial policies and a series of supporting national economic policies, China's mold industry has developed rapidly, with an average annual growth rate of 13%. In 1999, the output value of China's mold industry was 24.5 billion yuan, and by 2002, the total output value of China's mold industry was about 36 billion yuan, of which plastic molds accounted for about 30%. In the future mold market, the proportion of plastic molds in the total number of molds will gradually increase. 

From its inception to the present, China's plastic mold industry has undergone more than half a century of significant development, and the level of molds has been greatly improved. In terms of large molds, we are capable of producing injection molds for 48 inch large screen TV plastic cases, a complete set of plastic molds for 6.5kg large capacity washing machines, as well as plastic molds for car bumpers and integral instrument panels. In terms of precision plastic molds, we are capable of producing plastic parts molds for cameras, multi cavity small modulus gear molds, and plastic sealing molds. Such as Tianjin Jinrong Tianhe Electromechanical Co., Ltd. and Yantai North Star I K Mold Co., Ltd. manufactures multi cavity VCD and DVD gear molds, and the dimensional accuracy, coaxiality, and runout requirements of the gear plastic parts produced have reached the level of similar foreign products. In addition, the latest gear design software is used to correct the tooth profile errors caused by molding shrinkage and meet the standard involute tooth profile requirements. It can also produce the aviation cup mold with only 0.08mm thick the first mock examination and two cavities, and the difficult plastic door and window extrusion mold, etc. The manufacturing accuracy of injection mold cavity can reach 0.02mm~0.05mm, with a surface roughness of Ra0.2 μ m. The quality and service life of the mold have been significantly improved. The service life of non quenched steel molds can reach 100000~300000 times, and that of quenched steel molds can reach 500000~10 million times. The delivery time has been shortened compared to before, but there is still a significant gap compared to foreign countries. The specific data is shown in Table 1. 

In terms of molding technology, significant progress has been made in the innovation of multi material plastic molding molds, efficient multi-color injection molds, insert exchange structures, and core pulling and demolding mechanisms. The use of gas assisted injection molding technology is becoming more mature. Manufacturers such as Qingdao Hisense Mold Co., Ltd. and Tianjin Communication and Broadcasting Company Mold Factory have successfully applied gas assisted technology to molds for 29-34 inch TV casings and some thick walled parts. Some manufacturers have also used C-MOLD gas assisted software, achieving good results. Companies such as Shanghai New Pres can provide users with gas assisted molding equipment and technology. Hot runner molds have begun to be promoted, with some factories adopting rates of over 20%. Generally, internal or external hot runner devices are used, and a few units adopt high difficulty needle valve hot runner molds with world advanced levels. But overall, the adoption rate of hot runner is less than 10%, which is a significant gap compared to 50% to 80% in foreign countries. 

In terms of manufacturing technology, the application level of CAD/CAM/CAE technology has reached a new level. Represented by enterprises producing household appliances, a considerable number of CAD/CAM systems have been introduced, such as UG II from EDS in the United States, Pro/Engineer from Parametric Technology in the United States, CADS5 from CV in the United States, DOCT5 from Deltacam in the United Kingdom, CRADE from HZS in Japan, Cimatron from Israel, C-Mold from AC Tech in the United States, and MPA mold analysis software from Moldflow in Australia. The introduction of these systems and software has cost a lot of money, but in China's mold industry, it has achieved the integration of CAD/CAM and can support CAE technology for computer simulation of molding processes such as filling and cooling, achieving certain technical and economic benefits and promoting the development of mold CAD/CAM technology in China. In recent years, China's independently developed plastic mold CAD/CAM systems have made great progress, mainly including the CAXA system developed by Beihang Huazheng Software Engineering Research Institute, the injection mold HSC5.0 system developed by Huazhong University of Science and Technology, and CAE software. These software have the characteristics of adapting to the specific situation of domestic molds, being able to be applied on microcomputers, and being inexpensive, creating favorable conditions for further popularization of mold CAD/CAM technology. 

In recent years, some new plastic mold steels have been widely used in China, such as P20, 3Gr2Mo, PMS, SM Ⅰ, SM Ⅱ, etc., which have a direct and significant impact on the quality and service life of molds, but the overall usage is still relatively small. The standard mold frame, standard push rod, and spring for plastic molds are becoming increasingly widely used, and some domestically produced commercialized hot runner system components have emerged. But currently, the commercialization level of mold standardization in China is generally below 30%, which is still lagging behind advanced industrial countries abroad that have reached 70% to 80%.

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2、 The main development directions of China's plastic mold industry in the future will include:

1. Improve the design level and proportion of large, precise, complex, and long-life molds. This is due to the increasingly large-scale, complex and high-precision requirements of plastic molding products and the development of the first mock examination with multiple cavities due to the requirements of high productivity. 

2. Promote the comprehensive application of CAD/CAM/CAE technology in plastic mold design and manufacturing. CAD/CAM technology has developed into a relatively mature common technology. In recent years, the hardware and software prices of mold CAD/CAM technology have been reduced to a level that is generally acceptable to small and medium-sized enterprises, creating favorable conditions for its further popularization; The architecture of a network-based CAD/CAM/CAE integrated system is beginning to emerge, which will solve the problem that traditional hybrid CAD/CAM systems cannot meet the requirements of division of labor and cooperation in actual production processes; The intelligence level of CAD/CAM software will gradually improve; The 3D design of plastic parts and molds and the 3D analysis of the molding process will play an increasingly important role in China's plastic mold industry. 

3. Promote the application of hot runner technology, gas assisted injection molding technology, and high-pressure injection molding technology. The use of hot runner technology in molds can improve the productivity and quality of parts, and significantly save raw materials and energy for plastic parts. Therefore, the widespread application of this technology is a major change in plastic molds. Developing national standards for hot runner components and actively producing affordable and high-quality components is the key to developing hot runner molds. Gas assisted injection molding can significantly reduce costs while ensuring product quality. Currently, it is gradually being promoted and used in the automotive and home appliance industries. Gas assisted injection molding requires more process parameters to be determined and controlled than traditional injection processes, and is commonly used for complex large-scale products. Mold design and control are more difficult, so developing gas assisted molding flow analysis software is very important. On the other hand, in order to ensure the accuracy of plastic parts, it is also very important to continue researching and developing high-pressure injection molding processes and molds. 

4. Develop new molding processes and fast and economical molds. To adapt to the production mode of multiple varieties and small batches. 

5. Improve the standardization level of plastic molds and the utilization rate of standard parts. The level of mold standard parts and the degree of mold standardization in China are still relatively low, with a significant gap compared to foreign countries, which to some extent restricts the development of China's mold industry. In order to improve mold quality and reduce mold manufacturing costs, the application of mold standard parts should be vigorously promoted. To this end, it is necessary to first establish a unified national standard and strictly produce according to the standard; Secondly, it is necessary to gradually form large-scale production, improve the degree of commercialization, enhance the quality of standard parts, and reduce costs; Once again, it is necessary to further increase the specifications and varieties of standard parts. 

6. It is essential to use high-quality materials and advanced surface treatment techniques to improve the lifespan and quality of molds.

7. Research and apply high-speed measurement technology and reverse engineering for molds. One of the key technologies in plastic mold CAD/CAM is to use a coordinate measuring instrument or coordinate scanner for reverse engineering. The research and application of diverse, adjustable, and inexpensive detection equipment is a necessary prerequisite for achieving reverse engineering.