What types of seals are used in hydraulic cylinder?

Fri November 17, 2023


Using the Correct Seals to Ensure Effective Sealing in Hydraulic Cylinders

Seals hold the hydraulic fluid or gas inside the hydraulic cylinder seals and piston system of hydraulic cylinders. In a variety of industrial applications, the longevity and correct operation of hydraulic cylinders depend on the selection of the appropriate hydraulic cylinder seals.

Common Types of Hydraulic Seals hyd cylinder seals Used in Cylinders:

1,The Piston Seal-

Sealing Function
Piston seals are located between the piston and cylinder wall. Their main function is to stop the working media from leaking between the  hydraulic cylinder wall and the piston. Pneumatic cylinder operating efficiency can be increased with a good sealing effect.

Sliding Characteristics  
Reducing friction between the piston and cylinder wall is necessary to enhance mechanical efficiency and lessen motion resistance while the piston travels inside the hydraulic cylinder seals. To enhance the piston’s sliding performance, lubricating grease is applied to the inner surface of the seals, or sealing materials with favorable sliding properties are chosen.

Adjustability to Deformation of the Cylinder
The materials used for piston seals are ptfe, pu or typically elastic rubber, which can adapt to slight deformations of the hydraulic cylinder seals when pressurized, improving the sealing effect.

Wear and Resistance to High Temperatures
Wear and friction between the hydraulic cylinder wall and seals are caused by prolonged piston movement. Working conditions with high temperatures also hasten seal wear. Selecting materials that can withstand wear and high temperatures can extend service life.

Simple Installation and Takedown
Piston seals should be easy to install into the piston groove and easy to remove for maintenance due to their structural design. Equipment downtime can be decreased with prompt seal replacement.

Conformity with Lubricant  
Lubricating the piston is necessary to minimize wear and enhance sliding performance. In order to maximize the benefits of both sealing and lubrication, the seal material and lubricating oil should be compatible.

To ensure the proper operation of hydraulic cylinders under a variety of working conditions, piston seals must balance a number of characteristics, including sliding, deformation adaptability, wear resistance, and others. Piston seals play a significant role in sealing.

2,Rod Seal-

Sealing Function
From the hydraulic cylinder seals end cap to the exterior, the piston rod extends. To stop working medium from leaking between the rod and end cap, piston rod seals are fitted at the end cap. Hydraulic cylinder efficiency is increased by a good sealing effect.

Sliding Characteristics
The piston rod’s reciprocating motion must also reduce friction with the end cap. To increase slidability, sealing materials with good sliding qualities are applied to the piston rod seal surface.  

Adjustability to Deformation of the End Cap
Because piston rod seal materials have some give, they can adjust to small end cap deformations when operating pressure is applied, ensuring a good sealing result.

Wear and Resistance to High Temperatures
Wear of the piston rod seals is caused by prolonged friction. High-temperature, wear-resistant seal materials can increase lifespan.

Prevention of Dust  
Dust must be kept out of the hydraulic cylinder’s interior while the piston rod is extending from it. A certain level of dust prevention should be included in piston rod seal designs.

Conformity with Lubricant
To maximize the benefits of lubrication and sealing, the lubricating oil used on piston rods should be compatible with the material of the seal.

To ensure normal hydraulic cylinder operation, piston rod seals require good slidability, deformability, and dust resistance in addition to their sealing function.

3,Wear Ring-

Guiding Function
A specific amount of clearance between the guide rings and the piston’s outer surface is installed inside the cylinder barrel. The hydraulic cylinder seals’ radial motion of the piston can be precisely guided by the guide rings’ precisely machined inner diameter, which stops the piston from wobbling laterally.

Support Function  
The piston’s torsional moment is supported by guide rings, which keeps the piston from rotating inside the hydraulic cylinder. They have some axial load resistance as well.

Lubrication Function
Guide rings are constructed of self-lubricating materials or have lubricating grease applied to their inner surface. This enhances slidability by lowering friction between the guide ring and piston.

Dust Prevention Function  
Seal life can be increased by preventing dust particles from entering the hydraulic cylinder seals through the clearance between the guide ring and cylinder barrel.

Heat Insulation Function
In order to lessen the thermal effects on seals, guide rings offer some heat insulation by slowing the heat transfer between the cylinder end cap and piston end face.

Clearance Fit
It is necessary to precisely control the clearance fit between the guide ring and cylinder barrel in order to prevent axial looseness and still allow for installation and lubrication.

In summary, guide rings are crucial for increasing motion precision, decreasing friction losses, and extending the life of hydraulic cylinders. The overall performance of a hydraulic cylinder can be maximized by choosing the right guide rings.

4,Dust Ring-

Dust Prevention Function
At the two extremities of the hydraulic cylinder barrel are dust seals installed. They stop dust particles from entering the hydraulic cylinder interior and abrading parts like the piston and seals by cleaning the cylinder bore.

Sealing Function
By supplying a certain amount of sealing between the seal and the hydraulic cylinder end, dust seals help to stop leaks and environmental pollution.

Wiping Function
Dust seals, which are made of elastic materials, can hug the surface of the cylinder bore tightly to remove dust and maintain a clean bore.

Deformation Adaptability  
Dust seal materials’ elasticity enables them to adjust to minute hydraulic cylinder end deformations when under load.

Easy Replacement
Dust seals are simple to install and remove, making replacements quick and easy.

Lubrication Compatibility
The materials used for dust seals are compatible with hydraulic cylinder.

Low Friction
Dust seals with low friction coefficients are less resistant to motion because of material choices.

In summary, dust seals must balance sealing, wiping, deformability, and lubrication compatibility in addition to filtering dust to achieve good dust prevention and prolong hydraulic cylinder service life.

5,Buffer Ring-

Cushioning Function
Buffer Rings are installed at both ends of the cylinder barrel to provide cushioning and shock absorption. When the piston moves at high speeds, cushion seals can reduce the impact force as the piston strikes the end caps.

Sealing Function  
Cushion seals stop leaks by adding some sealing between the seal and the hydraulic cylinder seals end.

Cushion seal materials can self-adjust and conform to end cap deformations because of their elastic nature.
High Pressure Resistance
Materials for cushion seals are resistant to the high pressure conditions found inside cylinders.

Thermal Stability
Cushion seals must have strong thermal stability and durability to tolerate high temperatures in cyclic cylinder operations.

Easy Installation
The simple structure of cushion seals enables easy disassembly and replacement for maintenance.

Low Friction
Cushion seal  material selection provides low friction coefficients.

Besides shock absorption, cushion seals also need to balance sealing performance, deformability, and heat resistance to prolong hydraulic cylinder service life.

6,O-rings – The most popular type of seal hyd cylinder seals use. O-rings are made of rubber or other elastomeric materials. Their circular ring shape provides effective sealing through compression.

7,U-cups – With their U-shaped profile, U-cup seals offer enhanced compression flexibility suited for high-pressure sealing applications in hydraulic cylinder seals.

8,V-rings – The V-shaped cross-section of these seals allows larger sealing surface area and interface compared to O-rings, improving sealing performance.

9,Composite meterial seals –  employ rubber compounds bonded with fabric reinforcement. They provide excellent heat resistance in hydraulic systems.

10,Metal seals – Metal seals made of stainless steel or other alloys offer high rigidity. They are commonly used in high-speed, high-temperature seals.

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