The hydraulic cylinder uses hydraulic oil as the working medium to transfer movement through the change of the sealed volume, and transfer power through the pressure inside the oil. To establish the seal volume and build up the pressure, there must be a good enclosed space and avoid leakage.
Sealing is a mechanism that prevents the leakage of the working medium (internal leakage and external leakage) and prevents foreign objects (such as air, dust, water, etc.) from entering hydraulic components and hydraulic systems. The sealing element plays a decisive role in the design, service life, and function of the hydraulic cylinder. Here are some factors to be considered in the design of a hydraulic cylinder seal.
1) Work Temperature
When choosing a sealing ring, you should consider the temperature of the work environment in which the hydraulic cylinder will work. Low temperature will cause the sealing materials to harden and shrink, which will cause leakage. Whereas, if the temperature is too high, the sealing materials will be carbonized. Therefore, it is very important to choose the right sealing ring which can agree to the working temperature.
2) Work Pressure
If the system pressure is too high and the hardness of the seal is too small, the seal material will be squeezed out of the metal groove. It will affect the sealing effect and probably cause leakage, which will cause environmental pollution and reduce work efficiency. And the applicable working pressure for different types of seals is also different. Therefore, we should choose the right sealing materials according to working pressure.
3) Linear Velocity Of Hydraulic Cylinder
If the linear velocity of the hydraulic rod to stretch and withdraw is too high, it will cause heating up, dry grinding, and carbonization of the seal, which will cause leakage. Sometimes if it exceeds the usable linear velocity range of the seal, it may lead to premature wear and leakage of the seal.
4) The Stress Condition Of The Hydraulic Cylinder At Work
If the hydraulic cylinder rod is subject to lateral force, it is necessary to design a guide support seal ring to withstand the lateral force, otherwise, it will cause the hydraulic cylinder rod and the hydraulic cylinder end cover to touch and rub each other, which may create scratches and cause leakage.
5) Type Of Hydraulic Cylinder Working Medium (Hydraulic Oil)
If the seal is not compatible with the working medium, the seal material and the medium will dissolve in each other, and the seal will be softened or dissolved. Therefore, we should choose sealing rings that are compatible with the working medium.
6) Dust In The Work Environment
Heavy dust in the work environment may cause the seal to wear and cause leakage as a result. This is why we need to design a dust-proof seal to achieve leak-proof performance.
When the dust is particularly serious, it is even necessary to consider adding a corrugated sleeve to the hydraulic cylinder rod.
Secondly, even the correct seal requires a reasonable structural design. If the size of the seal does not match the metal groove, it may cause leakage.