What causes functional issues with silicone rubber seals?

From the perspective of current technology, the sealing and protection technology of many products still has certain defects in the actual process, such as waterproof sealing of our mobile phones, waterproof sealing rings of automotive lighting fixtures, etc. The use of silicone and rubber materials as sealing materials is the most common type of material. Therefore, silicone sealing rings, as a type of sealing component used in various aspects, often encounter unexpected functional problems during normal use and cannot demonstrate the effectiveness of the product. So, what are the considerable factors that affect it?

Influence of hardness and softness
Many times, the different softness of silicone products can completely change the functionality and structure of the product. Therefore, due to the selection of silicone sealing rings with different hardness and softness, unavoidable problems may occur during use, such as extrusion gaps, excessive stress, high hardness, product deformation without rebound, and other factors.

Gap issue
The gap problem can be divided into several factors. Firstly, it is due to the material of the rubber material. Many silicone materials have poor rebound force and insufficient tensile force due to the formula, resulting in insufficient force during use and leakage due to gaps. Processing problems of silicone ring manufacturers, such as making the product brittle and resulting in thin edge thickness, are prone to this problem. Making the product soft can cause the rubber material to have internal bulges and become immature, and long-term stretching and compression can cause deformation and gap problems.

Force process
O-type silicone rings are generally installed in several places, such as grooves, flat surfaces, and convex grooves. The installation method of each product is different, and its stress process will also affect the service life and function of the product. Therefore, in order to ensure the sealing performance, a reserved space is made for this storage. The different methods and stress levels of silicone rubber sealing rings are distinguished, such as how much they can withstand in flat installation and how tight they are when adjusted, and how much stress they can withstand in concave and convex surfaces, and how much size is reserved.

Compress permanently
Another indicator for evaluating the sealing performance of O-rings is the compression permanent cross shape of the selected material. Under pressure, the O-ring as an elastic element undergoes elastic deformation, and permanent plastic deformation also occurs as the pressure increases. Usually, to prevent permanent plastic deformation, the maximum allowable compression of O-rings is about 30% in static seals and about 20% in dynamic seals. When installing silicone sealing rings in grooves, they should be subjected to tension or compression. If the values of stretching and compression are too large, it will cause an excessive increase or decrease in the cross-section of the O-ring, as stretching by 1% will reduce the diameter of the cross-section by about 0.5%. For hole seals, the O-ring is in a stretched state, allowing a tensile force of 6%. For shaft seals, the O-ring is best compressed along its circumference, allowing a circumference compression of 3%.