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Piston rod is a moving part with frequent movements and high technical requirements. It is one of the main key components of the hydraulic cylinder.
01. Common materials for piston rods
The piston rod is a shaft-type part. It is relatively slender and has a relatively large length-diameter ratio. It is mainly made of the following materials:
1. 45# steel (also called CK45, 1045)
45# steel is a high-quality carbon structural steel with low hardness and easy cutting. After quenching, its surface hardness can reach 45~52HRC. It also has good cutting performance and high strength, toughness and other comprehensive mechanical properties, so it is one of the commonly used materials for shaft parts.
2. 40Cr steel
40Cr is a grade of alloy steel. “40” means the average carbon content of the steel is 0.40%, and Cr means the main alloying element in the steel is Cr (chromium), and its average content is less than 1.5%. After quenching and tempering, 40Cr steel has good comprehensive mechanical properties, good low-temperature impact toughness and low notch sensitivity. 40Cr steel has medium cold deformation plasticity, good machinability, poor weldability, and good toughness index.
3. 42CrMo steel (Corresponding to international 4140)
42CrMo steel is an alloy structural steel in terms of material classification. It has good mechanical properties and machinability and is widely used. It mainly has two types of materials: plates and round bars. Its comprehensive performance is better than 40Cr and has been recognized by the industry.
42CrMo steel is an ultra-high strength steel with high strength and toughness, good hardenability, no obvious temper brittleness, and high fatigue limit and multiple impact resistance after quenching and tempering treatment. It has good low-temperature impact toughness. 42CrMo steel is suitable for manufacturing large and medium-sized plastic molds that require certain strength and toughness.
4. Stainless steel
Stainless steel is resistant to weak corrosive media such as air, steam, and water. Commonly used materials are 304, 316, 402, duplex 2205, duplex 2507. These materials have good weldability, polishability, heat resistance, corrosion resistance, and corrosion resistance. Through precision cold drawing, fine grinding, high-precision polishing and other processes, the various technical indicators of the piston rods manufactured meet and exceed national standards, so they are often used in hydraulic cylinders.
02. Selection of piston rod material
1. The piston rod of the hydraulic cylinder is usually made of 45# steel, which is quenched and tempered, and the surface is turned and ground before being chrome-plated with a thickness of 0.03 to 0.05 mm.
Typical chrome-plated piston rods use 45# steel, which is an easy-to-process and weld material with high strength and wear resistance. You can expect tensile strengths of more than 80,000 psi, and you may also expect 0.0005 inches (1/2 thou) of chrome to further increase surface hardness and reduce the possibility of corrosion.
2. When there is large impact force, heavy load transmission, in order to make the piston rod have sufficient working strength, 40Cr steel can be selected.
3. In some special fields, due to environmental factors, the equipment needs to have corrosion resistance and other requirements. Stainless steel piston rod has corrosion resistance and acid resistance, and can also help improve fatigue strength. Long-term use will not cause wear of parts, so it is especially suitable for use in some high-strength large-scale equipment.
4. The piston rod is generally designed as a cylinder. If the diameter is larger, a hollow piston rod can be used.
There are two types of piston rods: solid rod and hollow rod. The solid piston rod is made of 35# and 45# steel, and the hollow piston rod is made of 35# and 45# seamless steel pipe.