The most important ten items for mold design learning: mold steel, structural design, mold processing, standard parts, flying mold, polishing / leather, mold assembly, cooling water path, and mold maintenance.
1. Die steel
Steel is the decisive factor of mold quality, and selecting reasonable steel is the most important. The criteria for selecting steel are:
① Requirements for injection molding materials – different plastics should use different steels, such as requirements for high polishing and corrosion resistance;
② Price – steel properties are good as long as they can be used, not the more expensive the better; Considering the cost factor of the die, the die steel shall be selected according to the die life to avoid unnecessary waste; Generally, the service life of P20 is about 300000; 2738, 500000 is no problem, H13 / 2344 is usually more than 800000-1000000, which can be selected according to the situation;
③ Heat treatment. The surface treatment of the mold is also very important. Nitriding – can enhance the surface hardness of steel and effectively prolong the service life of mold; Electroplating – it 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 the steel.
2. Structural design
The mature mold structure not only takes into account the material properties of the product – shrinkage rate, molding temperature, elastic tensile deformation coefficient, etc., but also takes into account the cooling water path and the speed of opening and closing the mold. A reasonable mold structure can effectively prolong the life of the mold and ensure the smooth production of the mold, improve the efficiency and reduce the cost.
3. Mold processing
Sharp tools make good work. The arrangement of mold process is particularly important. Reasonable process arrangement can speed up the production cycle, shorten the processing time and effectively save costs. Moreover, 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. Standard parts
The lowest piece of wood determines the capacity of the bucket. We all understand this, but when we do it, we often fail to notice it. The mold is the same. Although the standard parts do not directly participate in the molding, they control the operation of the whole mold. Good standard parts should be wear-resistant, hard enough, high precision and not deformed. There is a big difference in the price of standard parts of different brands. Therefore, do not blindly haggle over the price when making molds. Your molds will fall from Mercedes Benz to Volkswagen.
5. Collision (flying model)
It depends on the experience of die fitters. It seems simple work, but it is the most technical work.
Complex molds mainly focus on this Kung Fu. The plate mold is the simplest. The fractal surface is basically OK as long as there is no flash break. For example, the automobile parts mold is very troublesome. Not only is the fractal surface irregular, but also it often includes multiple sliders and top blocks.
At the same time, other problems of the mold can be improved and perfected through the contact, so it is a comprehensive work.
6. Polishing / leather texture
The polishing of mold is the last step of 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. Often 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
Mold assembly is just like assembling a machine. Every component and screw can not make mistakes. Otherwise, the consequences will be quite serious. At least, it will lead to product defects and affect production. At worst, it will completely damage the mold and cause scrapping. Therefore, the assembly work must be very careful.
During the assembly process, pay special attention to the cleaning of the mold, especially the waterways and screw holes, and be sure to blow the iron scraps inside, otherwise the customer will be very angry.
8. Hot runner or cold runner
In fact, this has the least impact on the quality of the mold, because the hot runner is generally the brand designated by the customer, especially some large customers. Foreign well-known brands do a very good job in quality and after-sales service, so there is generally no problem in quality, while the quality of some domestic hot runner is very different. In order to save costs and gain price advantages, some small enterprises use 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 and so on.
9. Cooling water circuit
People with mold experience know how important cooling is to a mold. Due to the increase of prices and labor wages, it is unimaginable to reduce the profit brought by each second of injection molding cycle in mass production of products. However, accelerating the production cycle will lead to the rise of the mold temperature. If it is not effectively controlled, the mold will be too hot to form, and even lead to the deformation, failure and scrapping of the mold. Therefore, excellent waterway design is particularly important, including the arrangement density, diameter and mutual connection of the waterways.
10. Mold maintenance
Mold maintenance mainly refers to the maintenance and repair in the production process.
The mold is like an automobile. If it is not used for a long time without maintenance, the mold may be scrapped. Therefore, after each use of the mold, comprehensive maintenance should be carried out, especially the rust prevention of the molding part and the rust prevention of the main moving parts. Because the mold needs to be connected with water during the production process, water may get on the mold during the installation or disassembly process, so it is necessary to ensure that the mold is dry, and then brush a layer of oil for protection.