The role of hydraulic oil is very great. In the actual use effect, it can not only effectively extend the life of the machine, reduce the maintenance cost, but also increase production capacity, improve work efficiency and increase the competitive advantage of enterprises. So how much do you know about hydraulic fluids? Let's take a closer look at hydraulic fluids.
1. Viscosity and viscose-temperature characteristics: viscosity is the main index of hydraulic oil, which has an important impact on the smooth operation of the system. When the viscosity is too small, the lubricating surface is easy to wear, so that the internal leakage and external leakage of hydraulic components increase, the pump volume efficiency decreases, and the oil temperature rises. When the viscosity is too large, the pump is difficult to suck oil, the energy loss of the flow process increases, the heating of the system increases, and the oil temperature also rises. Therefore, it must have the right viscosity. In most cases, hydraulic oil is generally used at 40℃ kinematic viscosity 11.0-60.0mm2/s.
Because the construction machinery generally works in the open air, the oil temperature changes with the temperature, so in order to ensure the stable work of the hydraulic system, the greater the viscosity index of the oil, the better. General anti-wear hydraulic oil viscosity index requirements are not less than 90, low temperature hydraulic oil is not less than 130.
2. Low temperature: The low temperature of hydraulic oil includes three aspects: 1) low temperature fluidity. 2) Low temperature priming. 3) Cryogenic pumpability. The latter two properties are mainly related to the low temperature viscosity of the oil. Therefore, the manufacturers of various hydraulic pumps have stipulated the lowest cold start viscosity of the hydraulic oil used for the hydraulic pump.
3. Oxidation stability: hydraulic oil is required to have good oxidation stability, in order to reduce the adverse effect of oxidation deterioration to form acid substances and sediments on hydraulic equipment, and extend the oil change period. It is usually required that the acid value reaches 2mgKOH/g for no less than 100h.
4. Rust resistance and corrosion resistance: the hydraulic system in the process of operation, inevitably mixed with some air and water, these air and water will cause corrosion of the metal surface, affect the accuracy of the hydraulic components. On the other hand, corroded particles fall off, causing wear and tear. At the same time, rust is the catalyst of oil oxidation metamorphism. Therefore, the hydraulic oil is required to have good rust and corrosion resistance, in order to ensure the normal operation of the hydraulic transmission system for a long time.
5. Wear resistance: pump and high-power oil motor are the main moving parts in the hydraulic system. It is often possible to be in a boundary lubricated state when starting and stopping. In this case, if the lubrication of hydraulic oil is poor, poor wear resistance, adhesive wear, abrasive wear and fatigue wear will occur, resulting in reduced pump and oil motor performance, shortened life, system production failure. Therefore, a certain amount of anti-wear and anti-extreme pressure additives are often added to hydraulic oil. Like tritoluene phosphate and zinc dialkyl dithiophosphate, to improve the wear resistance and extreme pressure resistance of the oil, to meet the lubrication requirements.
