1: Movement speed

The movement speed is very low (≤ 0.03/s), and it is necessary to consider the smoothness of equipment operation and whether there is crawling phenomenon. When the motion speed is high (≥ 0.8m/s), the ink used for lubrication may be damaged, and the sealing components may experience frictional heating due to poor lubrication, resulting in a significant reduction in lifespan. It is recommended that the rubber seal work within the speed range of 0.3m/s to 1.2m/s, which is suitable for sealing.

2: Temperature

Low temperature can reduce the elasticity of rubber composite seals, causing leakage and even making the entire oil seal hard and brittle. High temperature can cause the volume of the oil seal to expand and soften, resulting in a rapid increase in frictional resistance and a decrease in pressure resistance during movement. Suggest a continuous working temperature range of -10~+80 ℃ for rubber composite seals.

3: Work pressure

The oil seal has a requirement for starting pressure. Low friction performance should be selected for low-pressure operation Oil seals with low aerodynamic resistance. Below 2.5Mpa, rubber composite sealing is not suitable. When under high pressure, the sealing pressure should be considered, and there are special requirements for the processing of anti extrusion retaining ring grooves.

4: Working medium:

In addition to strictly selecting the working medium according to the manufacturer's recommendations, it is crucial to maintain the cleanliness of the working medium. The aging or contamination of oil not only causes components in the system to malfunction, accelerating the aging and wear of oil seals, but also the dirt inside may scratch or embed the seal, causing seal failure. Therefore, it is necessary to regularly check the quality and cleanliness of the oil seal, and replace the oil filter or oil according to the maintenance specifications of the equipment. Residual air in the oil cylinder can cause high compression and result in high temperatures, causing the oil seal to burn out or even carbonize. To avoid this situation, exhaust treatment should be carried out during the initial operation of the hydraulic system. The hydraulic cylinder should also run at low pressure and slow speed for several minutes to confirm that the residual air in the oil has been drained before it can work normally.

5: Lateral load

Generally, a support ring must be installed on the piston to ensure that the oil cylinder can withstand large loads. Seals and support rings play completely different roles. Seals cannot replace the support ring load. For hydraulic cylinders with lateral force, a strong load-bearing support ring must be added (a metal ring can be used for heavy loads) to prevent oil seals from leaking and experiencing abnormal wear when working under eccentric conditions.

6: Hydraulic impact

There are many factors that can cause hydraulic impact, such as the sudden collision of an excavator bucket with a stone, or the moment when a crane lifts or lowers a heavy object. Excluding other factors, for high-pressure and high flow hydraulic systems, when the actuator (hydraulic cylinder or hydraulic motor) changes direction, if the performance of the directional valve is not very good, it is easy to generate hydraulic shock. The instantaneous high pressure generated by hydraulic impact may be several times the working pressure of the system. Such high pressure can tear the oil seal or locally roll it into the gap in a very short period of time, causing serious damage. Generally, hydraulic cylinders with hydraulic impact should be equipped with buffer rings and retaining rings on the piston rod. The buffer ring is installed in front of the oil seal to absorb most of the impact pressure, while the retaining ring prevents the oil seal from being squeezed into the gap under high pressure and the root from being bitten.

7: Machining accuracy of oil cylinder

Experimental results have shown that when the surface roughness Ra of the moving working surface in contact with the oil seal exceeds 0.8 μ m, the leakage and wear values of the oil seal will directly increase. Therefore, it is recommended that the roughness of the moving working surface be Ra0.1~0.8 μ m To ensure the sealing performance of rubber plastic composite seals and avoid damaging the seals during assembly, the following aspects should be considered in the design and installation of hydraulic cylinders:

1) : Cylinder barrel

a: Material: Generally made of carbon steel, aluminum alloy, bronze, stainless steel, etc. can be used in low-pressure systems and situations with good friction conditions

b: Surface quality and roughness: The inner surface generally requires honing, polishing, or rolling, with a roughness of Ra0.1~0.8 μ m and no longitudinal or transverse knife marks.

2) Piston rod

a: Material: Generally carbon steel, chrome plated steel, aluminum alloy, bronze, stainless steel, etc. can be used in low-pressure systems and situations with good friction conditions.

b: Surface quality and roughness: The required roughness is Ra0.2~0.4 μ m, and the surface is coated with hard chromium after heat treatment. The piston rod of hydraulic cylinders used in construction machinery may be scratched by sand and gravel, and its surface hardness is required to be above HRC60.

c: Installation groove of oil seal

d: Local structural design

e: Wear resistant ring sliding fit gap f and oil seal extrusion gap g