Rubber product mold design and demolding

1. Rubber product mould

1) When designing the rubber product mold, it must be easy to demold, accurately conform to the contour and shape of the rubber product, and the structure must be simple, reasonable, and easy to operate to meet the technical requirements;

2) The mold should be maintained frequently to observe its cleanliness, whether it is deformed, whether the positioning is firm, whether the surface is smooth, etc.

2. The structure of rubber products is unfavorable. When designing rubber products, attention should be paid to its shape, thickness, and demolding slope, among which the demolding slope is the main factor. After the product is out of the furnace, the product cools and produces a centripetal shrinkage, which produces a large holding force on the core or pin, thereby hindering the demolding. If the demolding slope is increased, this resistance can be significantly reduced, and defects such as tearing of the product due to no slope can also be avoided.

3. Unreasonable product formulation. Insufficient vulcanizing agent and accelerator in the formulation, or unreasonable vulcanization temperature and time design, resulting in insufficient sulfur; or too much raw rubber rubber content, too much accelerator vulcanizing agent, etc., will also cause difficulty in demolding.

4. Production process In the production process of rubber molded products, injection pressure, holding pressure, vulcanization temperature, vulcanization time, etc. will also affect the difficulty of demolding. For example, if the injection pressure is too high, the mold parts will be elastically deformed and cause extrusion force. If the holding pressure injection force is too high and the time is too long, it will cause the pressure in the cavity to increase, generate greater internal stress, and cause deformation or deformation of the mold parts. Flashing occurs between the mating surfaces, making demolding more difficult.

The second is the demoulding method. Through the analysis of demoulding factors, we can use the following methods to avoid or solve the problem of difficult demolding.

1. The mold structure is reasonable, and the mold rigidity is improved as much as possible; timely maintenance of the mold, such as cleaning (plating, PTFE spraying, sandblasting), etc.

2. The structure design of rubber products should be easy to demould and have enough slope. 3. Choose a reasonable and appropriate viscosity formula. Properly adjust the vulcanization system, especially rubber products, increase the amount of accelerator; add carbon black for reinforcement or adjust the original formula.

4. If the vulcanization is unfamiliar, you can increase the vulcanization time and increase the vulcanization temperature. For products with more complex structures, pay special attention to the demolding method to improve the operation level of the demolding workers.

5. Reduce the frequency and amount of spray release agent, which can effectively prevent the release agent from contaminating the surface of the mold cavity, resulting in difficult mold sticking.
6. Use a certain amount of release agent.