How to Correctly Choose Hydraulic Oil for Hydraulic Presses

The four-column hydraulic press delivers hydraulic oil to the valve block under the action of the oil pump. The control system controls each valve so that high-pressure hydraulic oil reaches the upper and lower chambers of the hydraulic cylinder, prompting the hydraulic press to move. Hydraulic press is a device that uses liquid to transmit pressure.

Hydraulic oil is very important for four-column hydraulic presses and is one of the important measures to reduce machine wear. Choosing the correct hydraulic oil is directly related to the service life of the hydraulic machine.

When selecting oil for a four-column hydraulic press, you must first select the appropriate viscosity. The selection of oil viscosity should consider the structural characteristics, working temperature and working pressure of the hydraulic system. In the hydraulic transmission system, the oil pump is one of the most sensitive components to changes in hydraulic oil viscosity. Different types of pumps each have a minimum and maximum allowable viscosity. In order to reduce power consumption, oil with low viscosity should generally be used as much as possible. However, in order to lubricate key components and prevent leakage, hydraulic oil of appropriate viscosity needs to be selected.

1. Hydraulic Oil Model Classification

Hydraulic oil models are classified into three national standard categories: HL type, HM type, and HG type.

(1) HL type hydraulic oil is formulated from a refined, relatively high-depth medium base oil, plus antioxidant and anti-rust additives. According to the movement at 40 degrees Celsius, the viscosity can be divided into six grades: 15, 22, 32, 46, 68, and 100.
(2) HM types include high alkaline, alkaline low zinc, neutral high zinc and ashless types. According to the movement at 40 degrees Celsius, the viscosity is divided into four grades: 22, 32, 46, and 68.
(3) HG type has anti-rust and anti-oxidation properties. Moreover, a viscosity index improver is added, which has good viscosity-temperature characteristics.

2. Hydraulic Oil Model Usage

(1) HL hydraulic oil is used for lubrication in bearing boxes and low-pressure circulation systems of various machine tools where there are no special requirements for oil and the ambient temperature is above zero degrees Celsius. Such products generally have very good sealing adaptability, and the maximum operating temperature can reach 80 degrees Celsius.
(2) HM hydraulic oil is mainly used in hydraulic systems of heavy-duty, medium-pressure and high-pressure vane pumps, plunger pumps and gear pumps. In addition, this type of hydraulic oil is also suitable for medium-pressure and high-pressure engineering equipment and vehicle hydraulic systems.
(3) HG hydraulic oil has good anti-rust, anti-oxidation, anti-wear, and anti-stick-slip properties, so it is mainly suitable for lubrication systems that use machine tool hydraulics and guide rails.

The operating temperatures of hydraulic oils of different viscosity grades under different requirements are as follows.

There are many types of hydraulic oil on the market, and there are also many types of hydraulic machines. Although the functions of hydraulic oil are basically the same, it is still necessary to choose different hydraulic oils for different hydraulic machines. When selecting hydraulic oil, the staff should understand what it is mainly asked to do, and then choose the correct hydraulic oil for the hydraulic machine.

How to Choose the Right Hydraulic Oil for Hydraulic Press

Two methods are often used when selecting hydraulic oil. One is to select hydraulic oil according to the oil types and specifications recommended by the hydraulic press manufacturer’s samples or instructions. The other is to comprehensively consider the selection of hydraulic oil based on the specific conditions of the hydraulic machine, such as working pressure, working temperature, movement speed, type of hydraulic components and other factors.

When selecting, the main tasks to be done are: determining the viscosity range of the hydraulic oil, selecting the appropriate hydraulic oil variety, and meeting the special needs of the hydraulic system.
Usually selected according to the following aspects:

(1) According to different choices of hydraulic press working machinery

Precision machinery and general machinery have different viscosity requirements. In order to avoid deformation of machine parts caused by temperature rise and affect working accuracy, precision machinery should use hydraulic oil with lower viscosity.

(2) Select according to the type of hydraulic pump

The hydraulic pump is an important component of the hydraulic press. In a hydraulic press, its movement speed, pressure and temperature rise are high, and its working time is long, so the requirements for viscosity are stricter. So the hydraulic pump should be taken into consideration when choosing the viscosity.

(3) Select according to the working pressure of the hydraulic press

When the pressure is high, oil with higher viscosity should be used to avoid excessive system leakage and low efficiency. When the working pressure is low, it is better to use oil with lower viscosity, which can reduce pressure loss.

(4) Consider the working environment temperature of the hydraulic press

The viscosity of mineral oil changes a lot due to the influence of temperature. In order to ensure a more suitable viscosity at the working temperature, the influence of the surrounding ambient temperature must also be considered.

(5) Consider the movement speed of the working parts of the hydraulic press

When the moving speed of the working parts in the hydraulic system is very high, the flow rate of the oil is also low, the hydraulic loss increases randomly, and the leakage is relatively reduced, so it is better to use oil with lower viscosity.

(6) Choose the appropriate type of hydraulic oil

Choosing hydraulic oil from regular manufacturers can reduce hydraulic press machine failures and extend the life of the press machine.