Before initiating any pressure adjustment work, fully isolate the hydraulic power unit from the main power supply and relieve all residual stored pressure in the main circuit through the designated pressure relief port. Technicians should confirm all moving axes of the CNC machine are parked at a safe, stationary position, and no workpiece or tool is clamped in the working area that could shift unexpectedly during pressure tuning. All pressure measurement points should be fitted with properly calibrated pressure gauges, and the gauge range must be selected to cover 120% of the maximum expected working pressure to avoid over-range damage during testing.
Baseline pressure mapping for full circuit
Run the hydraulic system at idle speed for 10 to 15 minutes to bring the hydraulic oil up to its standard operating temperature, so viscosity stabilizes and pressure readings stay consistent across all test points. Record the static no-load pressure value of the main pump, then activate each individual hydraulic actuator one by one to log the real-time pressure reading under no-load movement. This full baseline mapping process helps identify any hidden pressure drop points caused by partially blocked filters, worn sealing elements, or improperly adjusted valve openings that could disrupt stable pressure control under working load. Every recorded value should be documented in sequence to create a clear reference for subsequent tuning and fault diagnosis.
Dynamic load pressure calibration
Mount a standard test workpiece with known clamping force requirements on the worktable, and run the machine through its full programmed machining cycle while monitoring pressure changes across the entire hydraulic circuit. Adjust the main system pressure regulating valve in small, gradual increments, and observe the pressure gauge response to confirm the system can maintain stable target pressure when the actuator encounters peak machining resistance. Avoid turning the adjustment screw too far in a single step, as sudden large pressure spikes can shock the hydraulic seals and cause premature wear of internal precision components. Verify that the pressure relief valve triggers at the pre-set upper limit to provide reliable overpressure protection for the entire system.
Real-time pressure stability maintenance
Check the condition of all hydraulic filters at scheduled intervals, as accumulated contaminants trapped in the filter element can create unintended flow resistance that causes unexpected pressure fluctuations during operation. Inspect all hydraulic piping connections for signs of minor external leakage, as even a tiny continuous leak will gradually reduce system pressure stability under long continuous production runs. Perform a full pressure calibration check every time the hydraulic oil is replaced, to ensure the new fluid with fresh viscosity properties works in sync with the adjusted valve settings and maintains consistent pressure output for all hydraulic functions of the CNC machine.
