Common CNC Lathe Faults

I. CNC System Faults

System cannot start or alarms

Symptoms: No display upon startup, screen flickering, system crash, frequent alarms.

Causes: Power module failure, corrupted system software/files, motherboard or memory failure, incorrect parameter settings.

Troubleshooting: Check power module voltage; try restarting the system or restoring factory settings; check program syntax and coordinate values; contact manufacturer technical support.

II. Mechanical Structure Faults

1. Spindle Faults

Symptoms: Spindle does not rotate, abnormal speed, abnormal noise, vibration, overheating, decreased accuracy.

Causes: Spindle bearing wear, spindle motor or inverter failure, broken drive belt, poor spindle lubrication or insufficient cooling.

Troubleshooting: Check the spindle lubrication and cooling system; check the motor and inverter connections; measure spindle runout and vibration; replace worn bearings.

2. Feed System Failure

Symptoms: Slow axis movement, vibration (creeping), abnormal noise, inaccurate positioning, overtravel alarm.

Causes: Worn guide rails or leadscrews, poor lubrication, loose connection between servo motor and driver, improper parameter settings.

Troubleshooting: Check guide rail and leadscrew lubrication and cleanliness; check motor and driver connection; recalibrate origin; adjust servo parameters.

III. Tool Magazine and Tool Changer Failure

1. Tool Changing Action Jammed or Failed

Symptoms: Tool changing timeout, incorrect tool position, tool cannot be clamped or released.

Causes: Worn tool magazine mechanical parts, insufficient air pressure, poor lubrication or foreign objects in the tool changing robot joints.

Troubleshooting: Check tool magazine air pressure; clean tool magazine metal chips; check tool disc positioning pins; adjust air pressure valve or replace worn parts.

IV. Hydraulic and Pneumatic System Faults

1. Insufficient Pressure or Abnormal Actuator Operation

Symptoms: Insufficient clamping force, abnormal opening and closing of the protective door, failure of the chip blowing function.

Causes: Hydraulic pump wear, air leakage, filter blockage, valve core malfunction.

Troubleshooting: Check hydraulic oil level and air pressure; clean or replace the filter; check air circuit sealing; adjust or replace valves.

V. Auxiliary Device and Sensor Faults

1. Limit Switch or Sensor Faults

Symptoms: Shaft movement not in place, alarm, automatic cycle interruption.

Causes: Limit switch engagement device failure, switch quality problem or damage.

Troubleshooting: Check whether the relevant limit switches are engaged normally; replace damaged switches or sensors.

VI. Process and Operation Faults During Machining

1. Workpiece Dimensional and Shape Errors

Symptoms: Dimensional deviations, poor surface roughness, taper, roundness deviations.

Causes: Tool wear or improper installation, decreased machine tool geometric accuracy (e.g., guide rail wear, spindle runout), improper process parameters, workpiece clamping deformation.

Troubleshooting: Reset the tool and check tool compensation; check machine tool geometric accuracy; optimize cutting parameters; improve clamping methods.

Core Principles of Troubleshooting:
1. Safety First: In case of a malfunction, immediately press the emergency stop button to cut off the power source.

2. Observation and Recording: Carefully check alarm codes, abnormal sounds, smoke, oil leaks, etc., and record them.

3. From Simple to Complex: First check basic items such as power supply, air pressure, and hydraulic pressure, then check the mechanical and electrical systems.

4. Using Tools: Use multimeters, oscilloscopes, etc., to measure voltage, current, and signal waveforms.