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Viscosity of hydraulic oil is an important indicator of hydraulic oil, if viscosity become smaller, it will increase the leakage, reduce volumetric efficiency; if viscosity become larger, viscous friction will increase, and may even cause cavitation or stuck phenomenon. General hydraulic system will choose hydraulic oil which movement of most of the revolving degrees l06m / s (50 ℃).
(1) viscosity-temperature performance
When hydraulic system start work, with the pressure loss and the oil temperature increase, if the viscosity of hydraulic oil viscosity is poor, will cause a significant decline in viscosity, causing poor lubrication, leakage increases, and will affect the work accuracy; if in the winter, viscosity increase will affect start. So hydraulic system need suitable temperature and small changes of viscosity. General hydraulic oil temperature index is above 90℃
(2) anti-rust performance
Because the tools may stay in wearhouse very long time,the hydraulic components are easy to get corrosion, which requires hydraulic oil has good anti-rust performance.
(3) good oxidation resistance
When the hydraulic system work, with the oil temperature gradually increased,oil more and more easily deteriorate, especially in high temperature conditions, the oxidation rate is very fast, oil oxidation will generate sludge sedimentation residue, system pollution will affect normal operation.
(4) anti-emulsification performance
Hydraulic oil mixed with water, the hydraulic stability of the poor material to generate hydrophilic organic acids and soap, the pump to emulsify under agitation, reducing lubrication, affecting the performance of pumps and valves.
(5) anti-foam performance
If the hydraulic oil has foam, will make the hydraulic system crawling and noise.
(6) lubrication performance
Hydraulic components with a small gap between the moving parts, generally from a few microns to 100 microns or so in order to improve the life of components, requiring the formation of high-intensity surface of the movement of the oil film in order to constitute a liquid lubrication and reduce wear and tear.
(7) freezing point
Requirements of hydraulic oil freezing point should be lower than 10 ℃ at least, otherwise, low temperature and oil viscosity increasing will affect the start or even work.
(8) to have good compatibility
Oil with a variety of materials can not afford or less from the chemical role in order to avoid deterioration failure.