Rubber Rings Wholesaler introduced why rubber products have "burned edges". From the perspective of technology research and development, the way to solve the problem is to prevent the problem, not to find a way to solve the problem.
1. Production process: From the three commonly used molding methods, injection molding, and injection molding, for the same rubber material, the chances of edge burnt are decreasing. In particular, the injection method can accurately preheat the rubber to a higher temperature before being injected into the cavity, which effectively shortens the process of heat transfer and vulcanization reaction of the rubber after the rubber enters the cavity, especially for thick-walled products with low hardness, It has incomparable superiority in preventing and solving the problem of burning edge. A product called BX024 produced by our company is a typical example, with low hardness (SHA35) and the thick wall (15.2mm*24.2mm*39mm). When using the injection molding process, there is obvious edge burning. After a variety of formula combinations, the product cannot be effectively eliminated. The low temperature and long-term vulcanization process have to be used. The production efficiency is low, and the vulcanization time of each molded product is long. After 10 minutes, the rubber was heated by microwave preheating and then injected. As a result, the curing time was effectively shortened and the edge burning phenomenon was also reduced. However, compared with injection, this method still has disadvantages: It takes a period of operation to inject into the cavity. Because of the danger of scorching, the rubber cannot be preheated to a high temperature, and the preheating temperature cannot be accurately controlled, and the rubber can be preheated uniformly, so it still cannot be used. The effect of the injection process.
2. Formula design: It is the basis of rubber product production. A good formula must not only meet the performance requirements of the product but also have good process performance and low cost to produce products smoothly and efficiently. For thick-walled low-hardness products, special consideration should be given to the possibility of "burning edges" when formulating. Try to choose softeners with low boiling point and low volatile content and pay attention to controlling the dosage; the selection of sulfur promotion system should pay attention to the selection of after-effect varieties as much as possible to obtain longer scorch time and vulcanization flat period; if possible, you can Adding additives that can improve the thermal conductivity of the rubber compound, so that the inner and outer rubber layers can be vulcanized simultaneously as much as possible to avoid the formation of "burned edges" conditions.
3. Mold design: It is also an effective way to avoid burning edges in mold design. For the mold structure of the product with the above characteristics, it is necessary to use a parting method that can disperse the exhaust as much as possible to avoid concentrated exhaust. If the appearance permits, you can also consider adding vent holes and vent grooves to help avoid " The problem of "burning edges" can also avoid the easy formation of glue lack of gas.
4. Vulcanization process: measures can also be taken to adjust. Low-temperature and long-term vulcanization is the most commonly used method. As the vulcanization temperature is reduced, the difference in vulcanization speed between the inner and outer layers of the rubber is shortened; at the same time, the volatile matter generated by vulcanization is reduced due to the decrease in temperature, so the edge burning phenomenon is also reduced. Reducing the clamping pressure, to a certain extent, disperses the concentrated leakage of vulcanized volatiles, and also has the effect of reducing "edge burning".