The demolding damage of liquid silicone rubber products has always been the most common quality pain point in the injection molding production process, such as pulling, whitening, tearing, etc., which often directly increases the product defect rate and increases the labor cost of post-processing. To avoid such problems from the root, it is not enough to rely solely on adjustments in a single link. It is necessary to coordinate measures from multiple dimensions, including mold structure design, optimization of the surface state of the mold cavity, precise matching of the ejection system, and fine control of the molding process, to reduce resistance during the demolding process layer by layer and prevent product damage caused by local stress concentration.

Eliminating demolding resistance from the design source is the most fundamental means to avoid demolding damage. In the early stage of mold development, it is necessary to set a reasonable demolding slope for the product. The demolding slope of conventional products is controlled between 1 ° and 3 °. For complex products with deep cavities and high aspect ratios, the slope can be appropriately increased to avoid the formation of a "tight" state of vulcanized silicone rubber in the mold cavity, greatly reducing the sliding friction resistance during ejection and minimizing the risk of pulling.

At the same time, attention should be paid to eliminating all sharp corner structures in the mold cavity, and smooth rounded transitions should be made at all corner positions. This not only prevents liquid silicone rubber from infiltrating micro gaps during the curing process and forming mechanical locks, but also avoids stress concentration and local tearing of soft products at sharp corner positions during demolding. It is also necessary to utilize the special characteristics of liquid silicone rubber, which expands when exposed to heat and contracts when exposed to cold, to plan in advance the position of the product after mold opening, so that the product can first stay on the side of the mold core with a more complete ejection structure, to avoid large areas of thin-walled products being stuck in the deep mold cavity and difficult to remove, and deformation and damage caused by manual force pulling.

By improving the surface condition of the mold and reducing the adhesion between silicone rubber and metal, additional resistance during the demolding process can be further reduced. Polishing the surface of the mold cavity to a mirror level of Ra0.025 or higher, completely eliminating the small pits on the surface, can prevent liquid silicone rubber from infiltrating these microscopic gaps and forming difficult to separate mechanical locks after solidification, greatly reducing the demolding strain caused by sticking to the mold.

On this basis, PTFE coating or diamond-like coating can also be deposited on the surface of the mold cavity, or a surface treatment scheme of PTFE composite nickel can be used to significantly reduce the adhesion between the rubber material and the mold, while extending the cleaning cycle of the mold. In large-scale production scenarios, it can greatly reduce the demolding failure rate. In the daily production process, it is also necessary to pay attention to regular maintenance of the mold cavity status, timely clean the accumulated sulfide deposits on the surface of the mold cavity, polish off the slight scratches generated during use, and avoid abnormal increase in surface roughness after long-term use, which may cause sudden increase in adhesion force and lead to batch mold strain.

The precise design of the ejection system is the key to ensuring uniform force distribution on the product during the demolding process. When designing, it is necessary to increase the number of ejection points as much as possible, so that the ejection force evenly covers the rigid support area of the product, avoiding excessive local pressure caused by a single ejection point, and directly penetrating and pressing through soft silicone rubber products with white texture.

For large-area thin-walled products, it is preferred to use the structure of the demoulding template as a whole to replace the traditional single point ejector pin structure, allowing the product to smoothly detach from the mold cavity under uniform support force, completely avoiding damage caused by local hard top.