What aspects should be paid attention to when choosing hydraulic oil?

As the temperature decreases, the viscosity of hydraulic oil increases, the pressure loss of the system is large, the efficiency decreases, and the oil suction condition of the pump deteriorates, which is prone to cavitation and cavitation, making the pump difficult to operate. If the viscosity is too low, the system will leak too much, the volume loss will increase, the system efficiency will be low, and the rigidity of the system will deteriorate. In addition, due to seasonal changes and changes in the temperature of hydraulic oil before and after starting and during normal operation of the four column hydraulic press, it is required that the viscosity of the working medium change less with temperature in order to ensure the normal and stable operation of the hydraulic system.
2. Lubricity
Excellent hydraulic oil lubricates the various moving parts in the hydraulic system of a four column hydraulic press, reducing friction and ensuring that the system can operate normally for a long time. In recent years, hydraulic systems and components have been developing towards high performance, and many friction components are in a boundary lubrication state. Therefore, hydraulic oil is required to have good lubricity.
3. Antioxidant
Hydraulic oil will undergo oxidation and deterioration when in contact with air. High temperature, high pressure, and certain substances such as copper, zinc, aluminum, etc. can accelerate the oxidation process. After oxidation, the acid value of the medium increases, and the corrosiveness is strong. In addition, the viscous substance generated by oxidation can block the holes and gaps of the components, affecting the normal operation of the system. Therefore, hydraulic oil is required to have good antioxidant properties.
4. Good shear stability
The working medium undergoes severe shear when passing through pumps, valves, and microporous components. This mechanical action will cause two forms of viscosity changes in the medium, namely temporary viscosity loss at high shear rates and permanent viscosity decrease caused by the destruction of polymeric thickening agent molecules. This situation is particularly severe at high speeds and pressures. After the viscosity decreases to a certain degree, it cannot continue to be used, therefore, it is required that the hydraulic oil has good shear stability.
5. Rust proof and non corrosive metals
Many metal parts in hydraulic systems come into long-term contact with hydraulic oil, and their surfaces will corrode under the action of dissolved moisture and air in the medium, causing damage to accuracy and surface quality. Corrosion particles circulating in the system can also cause accelerated component wear and system failure. At the same time, it is not allowed for the medium itself to have a corrosive effect on metal parts, or to slowly decompose and produce corrosive substances such as acids. Therefore, it is required that the oil used in hydraulic presses has good performance in protecting metals, preventing rust, and not corroding metals.