The injection mold manufacturing process is a complex process. From the steps of injection mold design, injection mold processing, injection mold assembly, mold debugging, etc., it can be put into use at the end. In the entire life cycle, the factors that affect the quality of the injection mold mainly include the following ten aspects.
1. Several commonly used sheets of steel for mold steels
Steel is the decisive factor of injection mold quality, and choosing reasonable steel is the top priority. The criteria for selecting steel are as follows.
① Requirements for injection molding materials
Different plastics should use different steels, such as high polishing requirements, corrosion resistance requirements, etc.;
② Price
The steel can be used as long as it can be used, not the more expensive the better; considering the cost factor of the injection mold, the mold steel should choose the material corresponding to the mold life to avoid unnecessary waste; generally the life of P20 is about 300,000; 2738, 500,000 No problem, H13/2344 is usually more than 800,000-1 million, you can choose according to the situation;
③ Heat treatment
The surface treatment of the mold is also very important. Nitriding can enhance the surface hardness of the steel and effectively extend the life of the injection mold; electroplating can effectively modify the mold steel. For some plastic injection molded parts that require high brightness and corrosion resistance, electroplating can be used to enhance and improve the performance of the steel.
2. Structural design, pipe fitting structure design
The mature mold structure not only considers the product material properties such as shrinkage rate, molding temperature, elastic tensile deformation coefficient, etc. but also considers the cooling water circuit and the speed of injection mold opening and closing. A reasonable mold structure can effectively extend the life of the injection mold and ensure the smooth production of the injection mold. Improve efficiency and reduce costs.
3. Injection mold processing
The arrangement of the injection mold process 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 injection mold in the production process and prolong life.
Some processing errors will cause injection mold welding, no matter how good the welding is, it is a loss to the injection mold; in addition, poor processing may also affect the mold operation, reduce the injection mold life, and cause the injection mold to crack during the production process. It even breaks.
4. Standard injection mold components
Although injection mold standard components are not directly involved in forming, they control the operation of the entire injection mold. Good standard injection mold components should be wear-resistant, hard enough, high precision, and not suitable for deformation.
5. Butt bump (flying mold)
Relying on the experience of the injection mold fitter, the seemingly simple job is the most technical job. Complex molds mainly depend on this technical ability. The flat mold is the simplest, as long as the fractal surface does not have flashing, it is basically fine. For example, auto parts molds are very troublesome, not only the fractal surface is relatively 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 job.
6. Injection mold polishing/skin texture
The polishing of the injection mold is the last link in the manufacture of the mold. Polishing is directly reflected on the plastic molded parts, so this is the most face-to-face job. Polishing can also help and supplement the action of the injection mold, especially for demolding. Often the production of some molds is not smooth because of improper lighting, excessive resistance, difficulty in demolding, and even whitening and cracking.
7. Injection mold assembly
The injection mold assembly is just like assembling a machine. Every component and every screw cannot be wrong, otherwise, the consequences will be very serious, from the slightest to the product defect, affecting the production, and the other to completely damaging the injection mold and causing scrap.
Therefore, the assembly work must be very meticulous. In the assembly process, pay special attention to the cleaning of the injection mold, especially the waterway and screw holes. The iron filings inside must be blown out, otherwise, the injection mold is prone to problems.
8. Hot runner
The cold runner actually has the least impact on the quality of the injection mold, because the hot runner is generally designated by the customer, especially some large customers. Well-known foreign brands are very good in quality and after-sales service. It’s just that the quality of some domestic hot runners is quite different.
In order to save costs and strive for price advantages, individual small companies use unreliable heating and conduction accessories, which are prone to problems. The main problem of the cold runner is how to ensure the balance of injection molding, gate size, injection pressure, and so on.
Anyone who has mold experience knows how important cooling is to an injection mold. Due to the increase in prices and human wages, when mass production of products, the profit that does not reduce the injection cycle of one second is unimaginable.
However, while accelerating the production cycle, the temperature of the injection mold will rise. If it is not effectively controlled, the injection mold will be too hot to form, and even cause the injection mold to deform and fail. Therefore, a good waterway design is particularly important, including the arrangement density, diameter, interconnection of the waterway, and so on.
10. Injection mold maintenance
Injection mold maintenance is mainly maintenance and maintenance during the production process. The injection mold is like a car. If it is not used for a long time without maintenance, it may cause the mold to be scrapped.
Therefore, every time the mold is used, comprehensive maintenance must be carried out, especially the rust prevention of the forming part and the rust prevention of the main moving parts. Because the mold needs to receive water during the production process, it may sleep on the injection mold during the installation or disassembly process, so you must ensure that the injection mold is dry, and then brush a layer of oil protection.
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