Hydraulic cylinders have a wide variety of applications such as construction, agriculture, manufacturing and other industries. And they are used to provide mechanical force to achieve pushing or lifting tasks. These working requirements make materials selection of hydraulic cylinders very important.
In this article, you will learn what materials are suitable for your hydraulic cylinders and key considerations about choosing them. I hope this article will help you choose suitable materials for your hydraulic cylinders and extend their service life.
What materials can you choose for Hydraulic Cylinders?
1. Steel
Steel is the most commonly used material for hydraulic cylinders, it has excellent performance of high tensile strength, good machinability and strong fatigue resistance.
Usually carbon steel and alloy steel are the most typical types of steel.
Carbon Steel has high tensile strength and is suitable for heavy loads and pressures in hydraulic systems. And its excellent welding properties allows hydraulic cylinder bottoms to be firmly connected to hydraulic cylinder barrels through a reliable welding process. This method can also help form an overall structure that can withstand huge impacts.
Alloy steel can be added chromium, nickel and molybdenum to better improve strength, hardness, resistance to wear and corrosion. These properties are sufficient to allow your hydraulic cylinders to withstand extremely high static and dynamic pressures. In addition, alloy steel can also extend hydraulic cylinders’ service life under harsh working conditions.
2. Stainless Steel
Stainless steel became high performance material for hydraulic cylinders due to its superior corrosion resistance. Chromium in stainless steel can create a very dense and stable passivation film on the surface, which can effectively resist moisture, chemicals or other corrosive media. This advantage makes stainless steel hydraulic cylinders particularly suitable for harsh environments. For instance, they can be exposed to moisture, seawater, corrosive atmospheres and will not rust or corrode easily.
Popular types of stainless steel are 304 and 316 stainless steel. 304 stainless steel is suitable for most common industrial requirements. But if your hydraulic cylinders need to operate in a more corrosive surroundings, you should choose 316 stainless steel because it has greater corrosion resistance and can help extend service life of your hydraulic cylinders.
3. Aluminum Alloy
Aluminum alloy, also known as Aluminum cylinder tube, is suitable for aerospace, automobile and other mobile hydraulic equipment because of its light weight. Even with that, aluminum alloys aren’t strong but still can deal with moderate pressure by adding copper, silicon and magnesium.
Furthermore, aluminum alloy has high corrosion resistance, it can form a dense oxide film on its surface. It also has excellent machining qualities and can be formed into any desired shapes for your hydraulic cylinder barrels.
4. Cast Iron
For one thing, cast iron has good wear resistance, which is ideal for internal hydraulic cylinder parts that are constantly subject to friction and reciprocating motion. These properties reduce wear rates between inner walls of hydraulic cylinder barrels and piston seals, extending the service life of piston seals.
For another, cast iron has far superior shock absorption properties than steel. It can not only
effectively reduce mechanical vibration in hydraulic systems and improve equipment operation stability, but also can control operating noise.
However, cast iron has insufficient toughness and relatively low tensile strength so it is usually not suitable for applications such as huge shock loads or ultra-high pressure working conditions.
5. Other Materials for Special Components
Bronze
Guide bushings and cylinder liners of hydraulic cylinders are often made of bronze because it is soft in texture. When it rubs against hard steel components, it can wear itself first to protect more important steel parts. It also has strong corrosion resistance and is particularly suitable for working in wet environments.
Rubber
Nitrile rubber, fluoro rubber and neoprene rubber are available choices for seals of hydraulic cylinders. Nitrile rubber is the most commonly used becuase of its absolute resistance to petroleum based hydraulic fluids, greases, aviation fuels etc. It is also extendable to most non-extreme hydraulic system operating temperatures between -30 °C and +100 °C.
If you require high temperature sealing materials then fluoro rubber should be considered, as it is able to cope with temperatures up to 200°C, while for outdoor use we have neoprene rubber grades due to its excellent weather and ozone resistance.
Key Considerations of Best Materials Selection
Environmental Conditions
Materials selection of hydraulic cylinders is deeply affected by environmental conditions.
For highly corrosive environments, materials with stronger corrosion resistance such as stainless steel, alloy steel and aluminum alloy should be considered. Especially those hydraulic cylinders that need contact with sea water or chemicals, these materials can improve their durability and reduce maintenance frequency.
Loading and Pressure Requirements
Loading and pressure requirements are decisive factors in material selection. Some industries like construction and mining machinery have higher requirements for loading and pressure, you can consider alloy steel because alloy steel has excellent toughness, which can ensure your hydraulic cylinders will not burst or permanently deform under extreme pressure. For moderate pressure and steady loading applications like ordinary machine tools, carbon steel or cast iron can meet the strength requirements.
Weight Considerations
On mobile hydraulic equipment such as engineering robotic arms, agricultural machinery and aerospace equipment, reducing weight means improving equipment maneuverability and reducing energy consumption. And weight is not a critical factor for stationary hydraulic equipment.
Different hydraulic cylinder types also have different material weight requirements. For example, telescopic hydraulic cylinders need to provide maximum stroke in the smallest installation space, so lightweight materials like aluminum alloy will be considered. But materials selection of hydraulic single acting cylinders focus more on strength and hardness of materials and carbon steel, stainless steel will be chosen.
Budget Constraints
Budget constraints are also realistic considerations in material selection. If you need cost-effective materials with a wide range of applications, carbon steel and cast iron are undoubtedly your reliable choice. If you require high performance and durable materials for your hydraulic cylinders, alloy steel and stainless steel can fit for your requirements.
Material’s Compatibility
It should be noted that materials must be compatible with hydraulic oil being used. Steel, cast iron, and stainless steel are all compatible with most hydraulic oil and will not produce chemical reactions with hydraulic oil to affect the normal operation of your hydraulic cylinders. But aluminum alloys may have specific compatibility requirements and you should choose suitable hydraulic oil according to the type of aluminum alloy.
Machinability
Carbon steel and cast iron are suitable for hydraulic cylinder barrels because they have excellent machinability and they can be easily machined into internal holes with precise dimensions and extremely low surface roughness. And carbon steel also has good welding performance so it can allow hydraulic cylinder bottoms to be firmly welded to hydraulic cylinder barrels and form a solid overall structure of hydraulic cylinder.
Conclusion
After reading this article, you should have mastered some considerations for selecting suitable hydraulic cylinder materials and this will greatly improve your hydraulic cylinders’ efficiency and service life of the entire equipment. If you have any requirements about selecting materials for your hydraulic cylinders, Target all can offer professional solutions to fit your needs.
FAQ
1. Can incorrect material selection reduce the performance of hydraulic cylinders?
Yes, incorrect materials selection will reduce the performance of your hydraulic cylinders.
On one hand, if your selected materials don’t have high strength, your hydraulic cylinder will not be able to withstand working pressure of its entire system and will be permanently deformed or even burst. On the other hand, if the material has poor wear resistance, it may accelerate components’ wear and even cause hydraulic oil leakage.
2. Are aluminum hydraulic cylinders strong enough for heavy-duty use？
No, aluminum alloy is not suitable for high loading applications. Although it can be added copper, silicon and magnesium to increase its strength, but it still cannot withstand high loading and is just suitable for moderate loading applications. In addition, its wear and scratch resistance is poor. If you have high loading capacity requirements, alloy steel can be considered.
3. What materials are the most popular choice for hydraulic cylinders?
Carbon steel is undoubtedly the most popular material for most hydraulic cylinders applications. Carbon steel is not only cost-effective, but also has high tensile strength and strong wear resistance. It can reliably withstand high pressure load inside your hydraulic system and external impact, providing a solid safety guarantee for cylinder barrels. But the cost of carbon steel is much lower than stainless steel and alloy steel and helps save your costs and achieve maximum manufacturing efficiency.
