When the hydraulic system is working, with the gradual rise of the oil temperature, the oil is more and more easy to oxidize and deteriorate, especially under high temperature conditions, the oxidation speed is fast, the oil oxidation, will generate sludge sediment, pollute the system, affect the normal work of the system. The selection of hydraulic oil of pipe bending machine has special effects: because the hydraulic system works, with the pressure loss and the oil temperature rises, if the viscosity and temperature performance of the hydraulic oil is poor, the viscosity will decrease significantly, thus causing poor lubrication, leakage increase, and affect the working accuracy.

Good anti-emulsification performance, hydraulic oil, such as mixed with water, the hydraulic oil in the safety of the poor substances generated hydrophilic organic acids and soap, in the pump stirring emulsification, reduce lubricity, affect the pump and valve performance.

Good foam resistance

If the hydraulic oil has foam, it will make the hydraulic system crawl and noise.

Good lubrication performance

The clearance of the moving parts of the hydraulic components is very small, generally from a few microns to about L00 microns in order to improve the life of the components, the formation of high strength oil film on the moving surface is required, so as to constitute liquid lubrication and reduce wear. The freezing point of the hydraulic oil is required to be lower than the minimum ambient temperature of 10℃, otherwise the temperature will be too low, the oil concentration will increase, affect the start, and even can not work.

If start in winter due to viscosity increase start. Therefore, the change range of viscosity should be small within the range of operating temperature. General hydraulic oil temperature index above 90.