558

Check hydraulic or pneumatic pressure gauge at the spindle drawbar circuit. Verify pressure meets specification (typically 20-25 bar for pneumatic, 15-50 bar for hydraulic depending on system).

Ensure machine is in a safe state before checking pressure systems.

Inspect drawbar pressure confirmation switches (typically located on spindle head). Clean switches and check for proper mounting, damage, or disconnected wiring.

Using PMC ladder or I/O diagnostic screen, monitor drawbar clamp/unclamp switch signals during M6 tool change cycle to identify which switch is not changing state.

Check for air/hydraulic leaks in lines, fittings, rotary union, and solenoid valves. Replace damaged components and bleed air from hydraulic systems if applicable.

Locate drawbar proximity switches on spindle head (usually two switches: one for clamp confirmation, one for unclamp confirmation). Check LED indicators on switches during manual drawbar actuation.

Manually actuate drawbar only when spindle is stopped and locked out.

Measure switch sensing distance with feeler gauges. Verify air gap is within specification (typically 0.5-2mm). Adjust mounting bracket if switch is too far from target.

Clean switch sensing face and target surface to remove metal chips, coolant residue, or contamination that may block magnetic field.

Test switch continuity and resistance with multimeter. Replace faulty proximity switches with exact OEM equivalent specifications (voltage, normally open/closed, sensing distance).

Remove any tool from spindle and manually actuate drawbar with air pressure. Listen and feel for smooth operation versus grinding, sticking, or abnormal resistance.

Lock out spindle rotation before manual drawbar testing.

Inspect drawbar tube and internal spindle bore for metal chips, coolant sludge, or galling. Clean thoroughly with appropriate solvent and compressed air.

Wear safety glasses when using compressed air.

Check Belleville spring stack for proper compression, cracks, or loss of spring tension. Springs should provide sufficient force to pull tool holder into taper (typically 1500-3000 lbs pull force depending on taper size).

Examine drawbar collet fingers, tool retention knob threads, and pull stud for wear or damage. Replace worn components and lubricate drawbar mechanism per manufacturer specifications.