Hydraulic Machine Selection And Requirements for Hydraulic Oil

●What Kind of Hydraulic Oil Is the Best Choice for Hydraulic Presses

To make the hydraulic system of the hydraulic machine better transmit power and movement, the hydraulic oil used should have the following properties:

⒈Have a suitable viscosity, better viscosity-temperature characteristics.

⒉Good lubrication, sufficient oil film strength within the specified range to avoid friction;

⒊The composition is more pure, fewer impurities, good anti-foaming property. If the hydraulic oil contains some mechanical impurities, it is easy to block the oil passage. If it contains volatile substances, it will cause bubbles in the oil and affect the smoothness of the movement;

⒋The flow point and freezing point are also relatively low, and the flashpoint and the ignition point are relatively high. When used in some high-temperature applications, the flashpoint is required for fire safety; when working in a low-temperature environment, the freezing point is required below. The hydraulic oil used in the hydraulic system of the hydraulic press has a flash point of about 130 to 150 degrees and a freezing point of about -15 to -10 degrees;

⒌It is preferred to have good thermal stability, hydrolytic stability, and oxidative stability, shear stability and compatibility;

⒍Has good demulsibility and rust and corrosion resistance, so as not to erode the parts and sealing components;

⒎Low body expansion coefficient, high specific heat capacity, and heat transfer coefficient;

⒏It has good safety, is harmless to the human body, and has the low cost.

●Hydraulic Machine Requirements for Hydraulic Oil

⒈Appropriate viscosity and good viscosity-temperature characteristics.

Excessive viscosity will lead to an increase in viscous drag loss; a large temperature rise; poor suction performance of the pump, difficulty in starting, and even cavitation; control sensitivity is reduced. Too low a viscosity will increase leakage and decrease volumetric efficiency; control accuracy will decrease; the liquid lubricating film will become thinner, and even liquid lubrication will not be formed to increase wear.

⒉Good abrasion resistance.

Abrasion resistance is a property that is not related to viscosity but is achieved by adding an additive to the oil to form an oil film on the opposite side of the friction pair.

⒊Good oxidation stability and thermal stability.

Oxidation stability refers to the ability of the oil to resist oxidation. The oil is oxidized by heat, oxygen, water, and metal substances in the air to form organic acids and polymers. The color of the hydraulic oil becomes darker, the acid value increases, the viscosity changes, and the precipitated substances are formed, so the corrosion of the hydraulic oil Increases blocks small holes in hydraulic components and exacerbates wear.

⒋The hydraulic press has good demulsibility and hydrolysis stability.

The ability of the oil to resist mixing with water to form an emulsion is called demulsibility. The ability of the oil to resist chemical reactions with water is called hydrolytic stability.

●How to Use Hydraulic Oil In Hydraulic Press Reasonably

⒈The system should be cleaned before changing the oil. Before the hydraulic system is used for the first time, it must be thoroughly cleaned. When replacing the same type of hydraulic oil, it should be flushed 1-2 times with the new hydraulic oil.

⒉Hydraulic oil cannot be mixed at will. If it has been determined that a certain grade of hydraulic fluid is selected, it must be used separately. Without the consent of the hydraulic equipment manufacturer and scientific basis, it is not allowed to mix with different viscosity grade hydraulic oils, or hydraulic oils of the same viscosity grade but not the same manufacturer, and should not be mixed with other types of oil.

⒊Note that the hydraulic system is well sealed, and the hydraulic system using hydraulic oil must maintain a strict seal to prevent leakage and mixing of various external pollutants.

⒋Replace the hydraulic oil in time according to the oil change indicator. The hydraulic oil in the hydraulic press should be sampled and tested regularly. Once the physical and chemical indicators in the oil reach the oil change index, the oil should be changed.