Mold manufacturing is a complicated process. From design, processing, assembly, debugging to final use, there are mainly 10 factors that affect quality of custom moulding throughout life cycle.
1. Mold steel
Steel is the decisive factor for mold quality. Choosing a reasonable steel is a top priority. The criteria for choosing steel are:
- Requirements for injection materials
Different plastics should use different steel materials, such as requirements for high polishing, corrosion resistance, etc. - Price
Enough steel properties is OK, not the more expensive the better. Considering cost of custom moulding, mold steel should use the material corresponding to life of mold to avoid unnecessary waste in plastic injection molding service. Life of P20 material is about 300,000; material 2738 is about 500,000, H13/2344 is usually more than 80-100 million, and it can be selected according to actual situation; - Surface treatment
Surface treatment of mold is also very important. Nitriding can enhance surface hardness of steel and effectively extend life of mold. Electroplating can effectively modify mold steel. For some high-brightness and corrosion-resistant plastic parts, electroplating can be used to enhance and improve performance of steel.
2. Structural design
Mature mold structure not only considers product material properties, shrinkage rate, molding temperature, elastic tensile deformation coefficient, but also consider cooling waterway, speed of opening and closing mold. Reasonable mold structure can effectively extend life of mold and ensure smooth production of mold, improve efficiency and reduce costs.
3. Mold processing
Sharp tools make good work. Arrangement of mold process is particularly important, and reasonable process arrangement can speed up production cycle, shorten processing time, and effectively save costs. And more importantly, accurate and reasonable processing can ensure stability and longevity of mold during production process. Some machining errors will lead to mold welding, no matter how good the welding is, it is a loss to custom plastic molding. In addition, poor processing may affect mold movement, reduce mold life, and cause mold to crack during production process or even broken.
4. Standard parts
The lowest wooden bar is capacity of bucket. Everyone understands this truth, but it is often not noticed when doing it. Same as custom molding, although standard parts are not directly involved in molding, but control the operation of entire mold. Good standard parts should be wear-resistant, hard enough, high precision, and not suitable for deformation. Different brands of standard parts are very different, so don’t just cut price, or your mold will drop from Mercedes to Volkswagen.
5. Fit mold
Fit relies on the experience of mold fitter. It seemingly be the most simple but technical work. This is the main part of complex mold. Flat mold is the simplest: basically no flash break on mould joint is acceptable.But for auto parts mold. Not only mould joint is relatively irregular, but it usually includes multiple sliders and ejector blocks. At the same time, it can improve and perfect other problems of mold through fit, so it is a comprehensive work.
6. Polishing/Texture
Polishing of custom plastic molding is the last step in the manufacture of custom molding. Polishing is directly reflected on the plastic parts, so this is the most important job. Polishing also helps and complements mold movement, especially for demolding. Usually some molds are not produced smoothly because poor polishing, large resistance, difficult demoulding, and scratch.
7. Mold assembly
Mold assembly is like assembling a machine in plastic injection molding service. Every component and every screw can’t go wrong. Otherwise, consequences will be quite serious. It will at least lead to product defects, affecting production, and worst of all damage mold and lead to scrapping. Therefore, assembly work must be very careful. In assembly process, especially pay attention to cleaning of mold such as waterway and screw holes. Ensure to blow off iron filings inside.
8. Hot runners or cold runners
This actually has the least impact on mold quality, because hot runners are generally branded by customers, especially some big customers. Well-known foreign brands do a good job in quality and after-sales service, so there is generally no problem in quality. However, some domestic hot runners have a very different quality. In order to save costs, small individual enterprises strive for price advantages with some unreliable heating and conduction accessories. The main problem with cold runners is how to ensure balance of injection molding, gate size, injection pressure.
9. Cooling Waterways
Anyone who has experience with molds knows how important cooling is for a custom plastic molding. Due to increase in prices and labor wages, it is incredible for the profit from every injection cycle reduced by one second. However, when production cycle is accelerated, temperature of mold will rise. If it is not effectively controlled, mold will be too hot to be formed. and even mold deformation will be scrapped. Therefore, excellent waterway design is particularly important, including arrangement density, diameter, and links between waterways.
10. Mold maintenance
Mold maintenance in plastic injection molding service is mainly maintenance during production process. Mold is like a car. If it is used for a long time without maintenance, it may cause custom molding to be scrapped. Therefore, every time mold is used, it must be fully maintained, especially rust prevention of molded part and rust prevention of main moving parts. Because mold has to be watered during production process, it may fall into mold during installation or disassembly process. So be sure to dry mold and then apply a layer of oil protection.
