Nowadays, when many rubber products manufacturers produce molded products, it is difficult to release the mold. So why is it difficult to demold? How to prevent the problem of difficult demolding?
First, let's understand the factors that restrict the release of rubber products:
1. Rubber product mould
(1) The rubber product mold must be easy to demold when designing, it must accurately conform to the contour and shape of the rubber product, the structure must be simple, reasonable, easy to operate and meet the technical requirements;
(2) The mold should be maintained in a regular manner, and observe its cleanliness, deformation, positioning firmly, and smooth surface.
2. The structure of rubber products is unfavorable. When designing rubber products, pay attention to its shape, thickness, and mold release slope, and the mold release slope is the main factor. After the product comes out of the oven, it will shrink centripetally due to the cooling of the product, which will cause a large holding force on the core or the pin, which will hinder the demolding. If the release slope is increased, this resistance can be significantly reduced, and defects such as tearing of the product due to no slope can be avoided. Generally, the product slope is between 1 ° and 3 °.
3. Unreasonable product formula Insufficient vulcanizing agent and accelerator in the formula, or unreasonable vulcanization temperature and time design, leading to undersulfurization; or too much rubber raw rubber content, too much accelerator vulcanizing agent, etc. will also cause mold release difficulties.
4. Production process In the production process of rubber molded products, injection pressure, holding pressure, vulcanization temperature, vulcanization time, etc. will also affect the ease of demolding. For example, if the injection pressure is too high, it will cause elastic deformation of the mold parts and cause squeezing force. If the holding pressure is too high and the time is too long, it will also cause the pressure in the mold cavity to increase, resulting in large internal stress, which will cause deformation of the mold parts or Flashing occurs between mating surfaces, making demolding more difficult.
Second is the demolding method. Through the analysis of the demolding factors, we can use the following methods to avoid difficult demolding problems or solve the difficult demolding problems.
1. The mold structure is reasonable, and the rigidity of the mold should be improved as much as possible; the maintenance of the mold should be done in a timely manner, such as cleaning (plating, spraying of PTFE, sandblasting), etc.
2. The structure design of rubber products should be easy to demold and have sufficient slope.
3. Select a reasonable and appropriate viscosity formula. Properly adjust the vulcanization system, especially rubber products, increase the amount of accelerator; add carbon black to strengthen or adjust the original formula.
4. If vulcanization is unfamiliar, it can be solved by increasing the vulcanization time and the vulcanization temperature; for products with more complex structures, special attention is paid to the demolding method to improve the operation level of the demolding workers.
5. The cost allows, you can add an appropriate amount of internal release paste to the rubber material, reduce the frequency and amount of mold release agent spraying, which can effectively prevent the release agent from contaminating the surface of the mold cavity, resulting in difficult to stick mold.
6. Use a certain amount of release agent.