The electro-hydraulic servo universal testing machine is a precise and valuable testing equipment, and its accuracy, stability, and service life greatly depend on standardized operation and systematic, periodic maintenance.
1、 Daily maintenance (after each test or daily)
Cleaning work:
After the experiment is completed, immediately clean the metal debris, oxide scale and other residues on the jaws and workbench.
Wipe the dust, oil stains, and sweat stains on the surface of the equipment with a clean cotton cloth to keep the host clean and dry.
Pay special attention to cleaning key moving parts such as the crossbeam guide rail and screw, and apply a small amount of rust proof oil.
Jaws and fixtures:
Check if the jaws are worn, damaged, or cracked.
Remove the sample in a timely manner after the experiment to avoid the fixture from being under stress for a long time.
Store the removed fixtures properly to prevent collision and corrosion.
Hydraulic system
Check if there is any looseness or oil leakage at the joints of each oil pipe.
Check if the oil level in the hydraulic oil tank is above 2/3 of the oil gauge (check when the equipment is stationary).
Shut down
Turn off the power to the host and control box.
If the equipment is not used for a long time, the jaws should be coated with anti rust oil.
2、 Regular maintenance (monthly or every 500 hours of operation)
Hydraulic oil inspection:
Check the color of the hydraulic oil. Normally, it should be light yellow or transparent. If the oil turns dark brown or cloudy, it indicates oxidation or contamination, and replacement should be considered.
Check for bubbles (emulsification) or impurities in the oil.
Filter element inspection:
Check the blockage of the oil suction filter and pipeline filter. Timely replacement of filter elements according to alarm prompts or maintenance cycles is one of the key measures to protect hydraulic pumps and servo valves.
Tightening inspection:
Check all fastening bolts and nuts for looseness, especially at the connections of load-bearing components such as bases, screws, and crossbeams.
Control system inspection:
Clean the ventilation filter of the control box to ensure good heat dissipation.
Check all cable connections for damage or looseness.
3、 Hydraulic oil replacement (annually or every 2000-3000 hours of operation)
Oil change cycle: Strictly follow the manufacturer's recommendations, usually one year or 2000 hours of operation, whichever comes first. In heavily polluted environments, the cycle should be shortened.
Oil change steps:
Heat engine: Turn on the machine to raise the oil temperature to 40-50 ℃, then turn off the machine, which is beneficial for removing sediment with the old oil.
Drain oil: Open the bottom drain port of the fuel tank and completely drain the old oil into the waste oil recycling bin.
Cleaning: Rinse the oil tank with new hydraulic oil or specialized cleaning oil. Add a small amount of new oil and run it without load for a few minutes before emptying it again. It is strictly prohibited to use cotton yarn to wipe the inside of the fuel tank to avoid fiber blockage of the oil circuit.
Refueling: After replacing the filter element, add the recommended brand of new hydraulic oil to the specified oil level.
Exhaust: After starting up, let the piston (crossbeam) run continuously without load multiple times to eliminate air from the hydraulic system.
Hydraulic oil grade: The anti-wear hydraulic oil specified in the equipment manual (such as N46 # or N68 # anti-wear hydraulic oil) must be used. Mixing different brands and grades of oil is strictly prohibited.
4、 Special maintenance of critical precision components
Servo valve (core component):
Ensuring the cleanliness of hydraulic oil is an important method for protecting servo valves. Oil contamination is the main cause of servo valve failure.
Non professionals are absolutely prohibited from disassembling or adjusting servo valves.
If there are problems such as decreased control accuracy, slow response, zero drift, etc., they should be inspected and calibrated by the manufacturer or professional engineer.
Force sensor, extensometer:
Handle with care to avoid collision, overload, and falling.
Regularly (annually) send the data to the national metrology department or third-party authoritative institutions for verification/calibration to ensure its accuracy.
When not in use, it should be stored properly in a dedicated box.
Ball screw and guide rail:
Regularly (every six months) remove old grease and apply new lithium based grease.
Keep the dust cover intact to prevent hard particles from entering the worn screw.
5、 Annual comprehensive maintenance and inspection
It is recommended to invite equipment manufacturers or professional service engineers to conduct a comprehensive inspection, maintenance, and calibration once a year, which includes:
System accuracy calibration: Calibrate the force value, deformation, and displacement system throughout the entire process.
Comprehensive inspection of hydraulic system: check the working status of oil pump, oil cylinder, seals, and valve group.
Control system inspection: Check the circuit, software performance, and accuracy of the data acquisition card.
Mechanical structure inspection: Check the stiffness, coaxiality, etc. of the host.
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