231-8420

Verify Cabinet Fan Operation

Open the control cabinet and verify all cooling fans are running. Check fan rotation direction matches airflow arrows on fan housing. Listen for abnormal bearing noise indicating imminent fan failure.

Disconnect mains power before opening cabinet. Wait 5 minutes for DC bus capacitors to discharge before touching components.

Measure Airflow Volume

Use an anemometer or airflow meter to check actual airflow velocity at power module heatsinks. Compare to cabinet specifications (typically 200-400 LFM minimum). Check that cabinet air filters are not clogged.

Heidenhain cabinets often have bottom-to-top airflow. Blocked intake filters at cabinet bottom are a common oversight during PM inspections.

Inspect Fan Power Supply

Check voltage at fan connectors (typically 24VDC or 230VAC depending on cabinet). Verify fan control relay is functioning if fans are thermostatically controlled. Replace failed fans with exact Heidenhain part numbers to maintain proper airflow characteristics.

Some TNC cabinets have fan monitoring contacts wired to PLC inputs - check the PLC diagnostics screen for fan failure indicators.

Measure Cabinet Ambient Temperature

Use infrared thermometer or place a calibrated thermometer inside the cabinet near the power modules. Record temperature with drives idle and under normal operation. Cabinet ambient should not exceed 40°C per Heidenhain specifications.

Check temperature at multiple heights - heat stratification can cause 10-15°C difference between top and bottom of cabinet.

Identify External Heat Sources

Look for heat-generating equipment mounted in or near the control cabinet (transformers, line reactors, braking resistors, VFDs for auxiliary equipment). Check if cabinet is exposed to direct sunlight or positioned near furnaces, welding equipment, or other heat sources.

Relocating or adding ventilation may require electrical code compliance review - consult qualified electrician.

Improve Cabinet Thermal Management

Install additional ventilation fans, add cabinet air conditioning unit rated for heat load, or relocate heat-generating components to separate enclosure. Ensure minimum clearances around cabinet for air circulation per Heidenhain installation manual.

Calculate total heat dissipation using drive current data from MOD > Diagnosis > Current actual values. Power modules dissipate approximately 3-5% of axis power as heat.

Monitor Drive Current in Real-Time

Press MOD function, select 'Diagnosis and Service', then 'Current actual values'. Observe the current draw on the affected axis (identified by %2.s in alarm). Compare actual current to motor nameplate rated continuous current. Document peak and RMS current values.

Access 'Machine Monitoring' screen to view historical current trends - this shows if overload is continuous or intermittent during specific operations.

Perform Manual Axis Movement Test

Enter Manual Operation mode and jog the affected axis through full travel range at reduced feedrate (10-25%). Listen for abnormal sounds, feel for binding or roughness. Check if current spikes occur at specific positions indicating mechanical interference or way damage.

Ensure work area is clear and machine guards are closed. Use reduced feedrate override for initial testing.

Inspect Mechanical Drive Components

Check ballscrew/linear motor ways for proper lubrication, check way covers for chips or debris causing binding, inspect coupling alignment between motor and ballscrew, verify counterbalance pressure (if equipped). Measure axis slide friction by disconnecting motor and checking manual movement resistance.

On rotary axes, check brake release - a dragging brake is a common cause of continuous high current and overheating.