Plastic mold manufacturing technology update trend
With the change of economic climate and the globalization of competition, the mould manufacturing industry has undergone dramatic changes in the past 10 years. Standardized basic spare parts are widely promoted and applied. More and more customers have production networks worldwide.
1. High-standard Engineering Technology
Only by continuously introducing 3D-CAD design, CAD/CAM and machining centers can the industrial production of dies and moulds be realized. Moreover, high speed milling (HSC) and combined workpiece processing have become the latest technology in the field of die manufacturing. These new developments have replaced traditional processes such as profiling milling and EDM, as well as line conductive EDM to a lesser extent. High-quality metal removal production technology has replaced the individual assembly and die assembly of die inserts, and replaced by centralized assembly.
Industrialized mold inserts, as well as single/multi-cavity molds, have uniformity and accuracy, which promotes the balance of the injection system.
2. New Injection Molding Technology
The imagination and ability of designers and production experts in die and mould manufacturing industry have also been tested. They have to translate the numerous innovations they have made in process engineering over the past decade into successful practices. Examples include multi-material and multi-color injection moulding, injection moulding with fabrics, films or painted surfaces.
The development of these die manufacturing technologies also requires close cooperation from customers (such as injection plants), end users, material and equipment manufacturers. Increasing die complexity (the number of cavity, the combination of different processes) also forces die manufacturing to become more standardized. Compared with the situation 10-15 years ago, it is difficult for ordinary die manufacturers to compete in today's market. However, changing product concept into die design will always be the main task of die manufacturing industry.
3. Micro-injection Molding Technology
The geometric shapes of these micro-injection parts are as diverse as those of large-scale injection parts.
There are two systems for the selection of forming micro-components. In this case, the die is equipped with a rotating plate, so that the complete object can be removed from the die.
The second is called variable temperature injection molding. The basic principle is to heat the die to the melting temperature of the processed plastic in each cycle to facilitate filling of the die cavity. Once the cavity is filled, it cools down again. In order to shorten the cooling time, as few die inserts as possible undergo temperature cycling. The remaining die structure is maintained at the demoulding temperature. Die inserts rely on electric heating, and its cross-sectional area determines the intensity of heating.
Cooling die inserts are quite challenging. Because of the small size, it is very difficult to have space to concentrate the cooling channel. They have very small cross-sectional area and high flow resistance to any cooling liquid. So air is the most ideal cooling medium.
In addition to cooling, another special problem is caused by die exhaust during micro-injection moulding. The exhaust can be accomplished through the boundary between the die inserts. At the present stage of development, the injection way is still large. In a four-type cavity mould, the contents of the cavity accounted for 30-50% of the injection weight. There is no hot runner system suitable for micro-injection moulding.
Micro-die can be made by Micro-etching or micro-machining. By EDM, the radius and roughness depth can reach 20 microns and 0.2 microns, while by wire conductive EDM, the radius and roughness depth can reach 30 microns and 0.1 microns.
Examples of micro-injection-moulded parts are the sensor housing of a portable hearing aid or the components of a micro-switch. In the experimental application, polyformaldehyde (POM) has been used to make plate elements with thickness of only 0.01-0.03 mm.
3. New steel improves accuracy
Steel produced by powder metallurgy or HIP (high temperature pressure equalization) method has been widely used, which has made an important contribution to the quality improvement of injection moulds. In this way, the high accuracy of the finished product can be maintained in long-term operation, and the size of the negative die can be deviated within the maximum range of 5 microns. In order to prevent spillover, the width of the exhaust slot must be less than 5 um.
Similar processes can be used for rubber processing. In this field, the compression technology of manual unloading moulding parts is still widely used. With the introduction of innovative concepts from silicone injection moulding, automated production of rubber products will gradually become possible in the future.
The transformation from compression to injection is an important prerequisite for improving working conditions. Usually a lot of water vapor and gas will be discharged during rubber vulcanization. Because the pressure is vertical, only insufficient gas can be pumped from the operator's position.
Automated injection moulding, including manual device to unload plastic parts, is the most effective tool for gas extraction.plastic mold
With the emergence of elastic forming parts, the application of liquid silicone may become more extensive than the processing of natural rubber. The combination of silicone and other materials has been considered feasible. And the injection moulds needed for these processes have emerged.
4. Injection assembly using multi-component moulds
Multicomponent die replacing single component of assembly is the remarkable feature of the mould manufacturing part in the injection equipment manufacturer. Injection moulds are the core of production departments. The acceptance of new product concepts promotes the integration of internal technology, resulting in cooperation among applied research, automation technology and mechanical engineering departments.
Generally speaking, the design of multi-color or multi-component injection moulding depends on the specified operation (complexity of finished products, number of parts produced, etc.). For each project, customer requirements determine the overall design plan and cycle time. The aim is to centralize any assembly process into the injection molding process, which has been continuously carried out so far.
The combination of different temperature and thermal diffusion ratios and different processing technologies has put forward great requirements for solving interdisciplinary problems.plastic mold
The market demand for quality improvement of complete structural parts, price competition and product individualization (design freedom) drives the systematic integration of injection moulds in the specialized field of multi-component products.