Maintenance of hydraulic system of CNC machine tools. 

Selecting the right hydraulic fluid

Hydraulic oil plays the role of pressure transmission, lubrication, cooling, and sealing in the hydraulic system, and improper selection of hydraulic oil is the main reason for early failure and durability of the hydraulic system. The hydraulic oil should be selected according to the grade specified in the "Instruction Manual", and when special circumstances require the use of substitute oil, the performance should be the same as the original grade. Different grades of hydraulic oil should not be mixed to prevent chemical reactions and performance changes of hydraulic oil. Dark brown, milky white, odorous hydraulic oil is degraded oil, can not be used.

Prevent solid impurities from mixing into the hydraulic system

Clean hydraulic oil is the life of the hydraulic system. There are many precision couples in the hydraulic system, some have small damping holes, some have gaps, and so on. If the invasion of solid impurities will cause the precision coupling strains, hairpin, oil channel blockage, etc., endangering the safe operation of the hydraulic system. General solid impurities invade the hydraulic system through unclean hydraulic oil; unclean refueling tools; refueling and repair, maintenance careless; hydraulic components debris, etc.

Cleaning of hydraulic system

The cleaning oil must use the same grade of hydraulic oil used in the system, the oil temperature is between 45~80℃, and the impurities in the system are taken away as much as possible with a high flow rate. The hydraulic system should be cleaned more than three times repeatedly, and after each cleaning, all of them should be released from the system when the oil is hot. After cleaning, clean the filter and replace it with a new filter element and fill it with new oil. Prevent air and water from invading the hydraulic system.

Prevent air intrusion should pay attention to the following points.

1) After repair and oil change, to be in accordance with the random "instruction manual" to exclude the air in the system, in order to normal operation.

2) Hydraulic oil pump suction pipe mouth must not be exposed to the oil surface, the suction pipeline must be well sealed.

3) The seal of the oil pump drive shaft should be good, we should pay attention to the replacement of the oil seal there should use "double lip" genuine oil seal, can not use "single lip" oil seal instead, because "single lip" oil seal can only seal oil in one direction, does not have the function of sealing gas.

Prevent water intrusion into the hydraulic system

Excess water in the oil will cause the hydraulic components to rust, oil emulsion degradation, lubricant film strength reduction, and accelerate mechanical wear.

In addition to the maintenance to prevent water intrusion, but also pay attention to the oil storage barrel when not in use, to tighten the lid, the best inverted placed; water content of the oil to be filtered several times, each filter to replace a drying filter paper, in the absence of special instruments to detect, can be dropped to the hot iron plate, no vapor and immediately burn before refilling.

Oil tank

 The oil level must be correct and the oil must be of the specified type and of the appropriate viscosity. For large systems, periodic oil sample analysis can be performed to confirm that the oil can continue to be used. Suction line: must be checked for damage and serious bending, it will reduce the diameter of the oil pipe and become a source of the noise.

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