5.Beacon

[2]Types of hydraulic oil and selecting appropriate one

There are various types of hydraulic oil. They can be systematically categorized as follows:

(1)Mineral-based hydraulic oil

This oil is generally used and can be easily obtained. Thus, most hydraulic equipment uses this type of hydraulic oil.

(2)Synthetic hydraulic oil

This oil been developed for aircraft-related uses that have special requirements, and has excellent temperature characteristics and low temperature fluidity. However, this type of hydraulic oil is expensive.

Phosphoric acid ester-based hydraulic oil, which is used as flame-resistant hydraulic oil, also belongs to this category.

(3)Aqueous hydraulic oil

This oil is used as flame-resistant hydraulic oil for those pieces of hydraulic equipment that are in extreme danger of fire that can be caused by oil leaking or other factors. Die casting machines, mills, and heating furnaces, for example, use this type of oil.

(4)Biodegradable hydraulic oil

This oil has been developed for the purpose of environmental conservation. This type of oil is decomposed by bacteria so that soil and rivers will not be contaminated by oil leaks.

Table 5 shows the compatibility of each type of oil with the motor. Select hydraulic oil by following this table.

Table 5. Compatibility of Hydraulic Oil with the Motor

: This type of oil has no problem to be used. : Please contact us if this type of oil needs to be used. × : Do not use these types of oil as they can cause a problem.

[3]Selecting hydraulic oil appropriate for the operating temperature

The viscosity of hydraulic oil varies depending on the operating temperature. Since the viscosity of hydraulic oil significantly affects lubrication and drive force transmission of the motor, changing to hydraulic oil appropriate for the operating temperature is necessary.

Check the operating temperature of the mother machine and the management temperature of the hydraulic oil in the hydraulic equipment, and then select hydraulic oil to use based on Table 6.

Hydraulic Oil Compatibility with the Motor Mineral-based hydraulic oil

Synthetic hydraulic oil ×

Aqueous hydraulic oil × Biodegradable hydraulic oil

Table 6. Operating Temperature and Appropriate Hydraulic oil

[4]Managing the temperature of the hydraulic oil 1. Temperature of the hydraulic oil in operation

Hydraulic equipment is very sensitive to the viscosity of the hydraulic oil. In particular, when the temperature of the hydraulic oil becomes too high in the operating hydraulic equipment, deterioration of the oil will be accelerated and the extremely reduced viscosity of the oil will cause a malfunction or breakdown of the equipment. Table 7 shows the applicable viscosity range of the hydraulic oil used in the hydraulic equipment.

Table 7. Applicable Viscosity Range of the Hydraulic Oil

For continuous operation, use a cooler or other equipment to keep the temperature of the hydraulic oils between -10 to +80°C and within the viscosity range shown in Table 7.

2. Temperature of the hydraulic oil at low temperature

To start the motor at low temperature when the temperature of the hydraulic oil is below the allowable range shown in Table 7, raise the temperature of the hydraulic oil using a warm-up operation or a heater and slowly start the motor. When the temperature of the hydraulic oil is too low, the hydraulic pump suction may be weakened due to too high viscosity or oil may not circulate due to excessive resistance.

Operating Environment Cold Area Warm Area Hot Area Environmental temperature -10 to +25°C 0 to +35°C

Appropriate hydraulic oil ISO VG32 or equivalent ISO VG46 or equivalent ISO VG56 or equivalent

Note

If the machine is used in an wide range of environmental temperatures from low to high, consult with your hydraulic oil manufacturer and use abrasion-resistant hydraulic oil with high viscosity (140 or higher) that can be used for all seasons.

Do not mix different types of hydraulic oil. To change to different hydraulic oil, flush the hydraulic circuit thoroughly before replacing.

Important

Viscosity Oil Temperature ISO VG32 ISO VG46 Appropriate range 25 to 100 cSt +17 to +45°C +23 to +55°C Allowable range 15 to 500 cSt -7 to +60°C 0 to +70°C

Important

When the viscosity of the oil is too low, the sliding section of the piston motor can be scorched or worn earlier and become unable to operate. Therefore, select hydraulic oil appropriate for the environmental temperature and the operating temperature.

WAt low temperatures, do not rapidly start the operation after you have raised the temperature of the hydraulic oil. The rapid flow of warm hydraulic oil into the cold equipment rises the temperature of the equipment. This may cause the valves to malfunction because of the difference in thermal expansion between the parts. Therefore, start the operation slowly to gradually raise the temperature of the equipment.

Important

[5]Managing the degree of contamination in the hydraulic oil

The gap between the parts such as the piston motor and the double counter balance valve is very small, thus very sensitive to contamination in the hydraulic oil. Dirty hydraulic oil can cause a problem such as malfunction of valves and performance degradation. To prevent this problem, keep the degree of contamination in hydraulic oil within the level of NAS rank 9.

To manage the contamination in the hydraulic oil, set a filter in the hydraulic circuit. (See Chapter 5.) A dirty filter may reduce the filtering performance of the hydraulic oil, or worse, contaminate the oil. Therefore, use a filter with an indicator that allows checking the filter clog from outside and a built-in relief valve that can bypass the flow according to clog state.

To properly manage the degree of contamination in the hydraulic oil, the filter must also be managed. Regularly conduct maintenance checks for the filter.

Note

Important