Nowadays, when many rubber products manufacturers produce molded products, it is difficult to demould, which has become a common problem. So why is demoulding difficult? How to prevent the difficult problem of demoulding?

First, let's understand the factors restricting demoulding of rubber products:

1. Rubber product mould

(1) When designing the rubber product mould, it must be easy to demould, accurately conform to the outline and shape of the rubber product, and the structure should be simple, reasonable and easy to operate to meet the technical requirements;

(2) The mould shall be maintained frequently, and its cleanliness, deformation, firm positioning and smooth surface shall be observed.

2. The structure of rubber products is unfavorable. When designing rubber products, pay attention to its shape, thickness and demoulding slope, of which demoulding slope is the main factor. After the product is discharged from the furnace, the centripetal shrinkage is generated due to the cooling of the product, resulting in a great clamping force on the core or pin, which hinders demoulding. If the demoulding slope is increased, this resistance can be significantly reduced, and defects such as tearing of products caused by no slope can also be avoided. Generally, the inclination of products is between 1 ° ~ 3 °.

3. The product formula is unreasonable, the vulcanizing agent and accelerator in the formula are not enough, or the vulcanization temperature and time design are unreasonable, resulting in sulfur deficiency; Or too much raw rubber content, too much accelerator and vulcanizing agent will also lead to difficult demoulding.

4. Production process in the production process of rubber molded products, injection pressure, pressure holding pressure, vulcanization temperature and vulcanization time will also affect the difficulty and ease of demoulding. For example, if the injection pressure is too high, the mold parts will be elastically deformed, resulting in extrusion pressure. If the pressure maintaining injection force is too high and the time is too long, it will also lead to the increase of pressure in the mold cavity, resulting in large internal stress, resulting in the deformation of mold parts or flash between mating surfaces, making demoulding 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 difficult demoulding problem.

1. The die structure is reasonable and the die stiffness shall be improved as much as possible; Timely do a good job in mold maintenance, such as cleaning (electroplating, Teflon spraying, sand blasting), etc.

2. The structural design of rubber products shall be easy to demould and have sufficient slope.

3. Select reasonable and appropriate viscosity formula. Properly adjust the curing system, especially rubber products, and increase the amount of accelerator; Add carbon black for reinforcement or adjust the original formula.

4. If the vulcanization is not mature, it can be solved by increasing the vulcanization time and temperature; For products with complex structure, special attention is paid to demoulding methods to improve the operation level of demoulding workers.

5. If the cost allows, an appropriate amount of internal release paste can be added to the compound to reduce the frequency and amount of release agent, which can effectively avoid the release agent polluting the surface of the mold cavity, resulting in difficulty in sticking the mold.

6. Use a certain amount of release agent.