Basic maintenance and care of CNC lathes

CNC lathes are characterized by the integration of machinery, electricity, and hydraulics, making them technology-intensive and knowledge-intensive. They are advanced processing equipment with a high degree of automation, complex structure, and high cost. To fully utilize their benefits and reduce the occurrence of faults, daily maintenance work must be done well. Therefore, CNC lathe maintenance personnel must not only have knowledge of mechanics, processing technology, and hydraulic and pneumatic systems, but also possess knowledge of electronic computers, automatic control, drive, and measurement technology. This comprehensive understanding is essential for effective maintenance.

1. The main daily maintenance and upkeep tasks for CNC machine tools:

1. Choose a suitable operating environment: The operating environment of CNC lathes (such as temperature, humidity, vibration, power supply voltage, frequency, and interference) can affect the normal operation of the machine. Therefore, when installing the machine, it is essential to strictly adhere to the installation conditions and requirements specified in the machine's manual. If economic conditions permit, CNC lathes should be installed separately from ordinary machining equipment to facilitate maintenance.

2. Specialized personnel should be assigned for programming, operation, and maintenance of the CNC system: These personnel should be familiar with the mechanical parts of the machine, the CNC system, high-voltage equipment, hydraulics, pneumatics, and the operating environment and processing conditions, and should be able to use the CNC lathe correctly according to the machine and system manuals.

3. Maintenance and upkeep for CNC lathes that are not used for a long time: When the CNC lathe is idle, the CNC system should be powered on regularly, allowing it to run empty while the machine is locked. During humid rainy seasons, it should be powered on daily to utilize the heat generated by electrical components to drive away moisture from the CNC cabinet, ensuring the stable and reliable performance of electronic components.

4. Maintenance and upkeep of the hardware control parts in the CNC system: An experienced maintenance electrician should check it once a year. Check whether the relevant reference voltages are within the specified range, such as the output voltages of the power module and the reference voltage of the CNC unit. If abnormal, clean the dust; check whether the connections of various electrical components in the system are loose; check whether the fans of each functional module are operating normally and clean the dust; check whether the connections of the external regenerative discharge units used by the servo amplifier and spindle amplifier are reliable and clean the dust; check whether the voltage of the backup batteries for the memory used by each functional module is normal, and generally replace them regularly according to the manufacturer's requirements. For machines that have been idle for a long time, they should be run for 4 hours each month to extend the service life of the CNC machine.

5. Maintenance and upkeep of the mechanical parts of the machine: Operators should clean up the chips scattered on the drag plate, guide rails, etc., after each shift of processing; during operation, they should check whether the chip removal device is functioning properly to avoid chip accumulation, which could damage the precision of the guide rails and jeopardize the lifespan of the ball screw and guide rails; before finishing work, all servo axes should return to the origin before stopping the machine.

6. Maintenance and upkeep of the spindle motor: Maintenance electricians should check the servo motor and spindle motor once a year. Focus on checking their operating noise and temperature rise. If the noise is too loud, investigate the cause, whether it is a mechanical issue like bearings or a parameter setting issue with the matching amplifier, and take appropriate measures to resolve it. For DC motors, check, adjust, repair, or replace the brushes and commutators to ensure they are in good working condition. Check whether the cooling fan at the motor end is operating normally and clean the dust; check whether the connection plugs of the motor are loose.

7. Maintenance and upkeep of the feed servo motor: For the servo motors of CNC lathes, maintenance should be performed every 10 to 12 months, and for machines with frequent acceleration or deceleration changes, maintenance should be performed every 2 months. The main maintenance tasks include: blowing off dust from the brushes with dry compressed air, checking the wear of the brushes, and if replacement is needed, selecting brushes of the same specifications. After replacement, run the motor without load for a certain period to ensure it matches the surface of the commutator; check and clean the armature rectifier to prevent short circuits; if equipped with a speed sensor and pulse encoder, they should also be checked and cleaned. The DC servo motors in CNC lathes should be checked at least once a year, generally under conditions where the CNC system is powered off and the motor is completely cooled; remove the rubber brush cap, unscrew the brush cover with a screwdriver to take out the brushes; measure the length of the brushes. If the brushes of a FANUC DC servo motor have worn from 10mm to less than 5mm, they must be replaced with the same model; carefully check whether the arc contact surface of the brushes has deep grooves and cracks, and whether there are any burn marks on the brush springs. If any of these phenomena occur, consider whether the working conditions of the motor are excessively harsh or if there is a problem with the motor itself. Use compressed air free of metal powder and moisture to blow into the brush holes, cleaning off the brush dust stuck to the walls of the holes. If it is difficult to clean, gently use the tip of a screwdriver to clear it until the walls are completely clean, but be careful not to touch the surface of the commutator. Install the new brushes and tighten the brush cover. If new brushes are replaced, the motor should run without load for a period to ensure the surfaces of the CNC lathe brushes and the commutator match.