Ten factors for improving die quality
plastic injection mold
The mold manufacturing process is a complex process. It can only be put into use in the end from the design, processing, assembly, debugging and other steps. In the entire life cycle, the factors that affect the mold quality mainly include the following ten aspects:
1. Mold steel Several common steels
Steel is the decisive factor of mold quality, and selecting reasonable steel is the top priority. The criteria for steel selection are:
① Requirements for injection molding materials – different steels shall be selected for different plastics, such as requirements for high polishing and corrosion resistance;
② Price – the steel can be used, not the more expensive the better; Considering the cost factor of the mold, the mold steel should be made of materials corresponding to the mold life to avoid unnecessary waste; Generally, the service life of P20 is about 300000; 2738, 500000 yuan is OK, H13/2344 is usually more than 800000 yuan to 1000000 yuan, which can be selected according to the situation;
③ Heat treatment. The surface treatment of mould is also very important. Nitriding – it can enhance the surface hardness of steel and effectively extend the service life of mold; Electroplating can effectively modify the die steel. For some plastic parts requiring high brightness and corrosion resistance, electroplating can be used to enhance and improve the performance of steel
2. Structural design Structural design of pipe fittings
The mature mold structure not only takes into account the product material properties – shrinkage, molding temperature, elastic tensile deformation coefficient, etc., but also takes into account the cooling water path, mold opening and closing speed, etc. The reasonable die structure can effectively prolong the life of the die and ensure the smooth production of the die. Improve efficiency and reduce costs.
Sharp tools make good work. The mold process arrangement is particularly important. A reasonable process arrangement can speed up the production cycle, shorten the processing time, and effectively save costs. And more importantly, accurate and reasonable processing can ensure the stability of the mold in the production process and prolong its life.
Some processing errors will lead to mold welding, no matter how good the welding is, it is a loss to the mold; In addition, poor processing may also affect the action of the mold, reduce the life of the mold, and cause the mold to crack or even break in the production process.
4. The standard part determines the bucket capacity by the lowest piece of wood. We all understand this principle, but we often fail to notice it when doing it. The same is true of molds. Although standard parts do not directly participate in molding, they control the operation of the entire mold. Good standard parts should be wear-resistant, hard enough, high precision, and should not be deformed. There is a big price difference between standard parts of different brands, so don’t just haggle over the price when making moulds. Your moulds have been reduced from Mercedes Benz to the public.
5. Butt to butt (flying mold) Butt to butt is based on the experience of the mold fitter. The seemingly simple work is the work with the most technical content. This is the main focus of complex molds. The flat die is the simplest. As long as there is no flash and break difference on the fractal surface, it is OK. For example, the mold for auto parts is very troublesome. The fractal surface is not only irregular, but also often includes multiple sliders and top blocks. At the same time, other problems of the mold can be improved and perfected through the collision. So it is a comprehensive work.
6. Polishing/leather mold polishing is the last link in mold manufacturing. Polishing is directly reflected on the plastic parts, so this is the most face saving work. Polishing can also help and supplement the mold action, especially for demoulding. Sometimes the production of some molds is not smooth because the polishing is not in place, the resistance is too large, the demoulding is difficult, and even the top is white and cracked.
7. Mold assembly The mold assembly is just like the assembly machine. Each part and each screw must not make mistakes, otherwise the consequences will be quite serious, ranging from product defects to affect production, to complete damage to the mold, resulting in scrapping. Therefore, the assembly work must be very meticulous. During the assembly process, especially pay attention to the cleaning of the mold, especially the waterway and screw holes. Be sure to blow out the iron filings inside, otherwise the customer will be very angry.
8. Hot runner or cold runner actually has the least impact on the mold quality, because hot runner is generally the brand designated by customers, especially some big customers. Foreign famous brands do a very good job in terms of both quality and after-sales service, so there is generally no problem in terms of quality. However, the quality of some domestic hot runner varies greatly. In order to save costs, some small enterprises strive for price advantages by using unreliable heating and conduction accessories, which is easy to cause problems. The main problem of cold runner is how to ensure the balance of injection molding, gate size, injection pressure, etc.
9. Everyone who has experience in mold cooling water circuit knows how important cooling is to a mold. Due to the increase of prices and human wages, it is unimaginable that the profits brought by the injection molding cycle can not be reduced by one second when the products are produced in large quantities. However, speeding up the production cycle will also lead to the rise of the mold temperature. If it is not effectively controlled, the mold will be too hot to form, or even lead to die deformation, failure and scrap. Therefore, a good waterway design is particularly important, including the layout density, diameter, links between waterways, and so on.
10. Mold maintenance Mold maintenance is mainly the maintenance during production. The mold is just like a car. If it is not used for a long time without maintenance, the mold may be scrapped. Therefore, every time the mold is used, comprehensive maintenance shall be carried out, especially the rust prevention of the forming part and the main moving parts. Since the mold needs to be watered during production, it may fall asleep on the mold during installation or disassembly, so make sure the mold is dry, and then brush a layer of oil for protection.
