A CNC machine tool is mainly composed of three major parts: numerical control system, servo system and machine body. Routine maintenance shall follow standardized daily, weekly and monthly inspections to effectively extend equipment service life and ensure machining accuracy.
I. Basic Structure of CNC Machine Tools
1. Numerical Control System
As the control core of CNC machine tools, it consists of input and output devices plus numerical control units. It receives and processes CNC machining programs, and outputs command signals to the servo system. This is the key feature that differentiates CNC equipment from ordinary machine tools.
Its core components include the operation panel and main control board. External equipment such as display screens and keyboards serve as input and output interactive devices.
2. Servo System
It acts as the motion executive component of the machine tool. It converts pulse signals from the numerical control unit into movement of machine moving parts, and controls the precise positioning and trajectory movement of worktables or cutting tools. Its precision and dynamic response directly determine the machining accuracy of the CNC machine tool.
The system mainly includes drive units and actuators. Common actuators cover stepping motors, AC/DC servo motors, equipped with detection and feedback devices to correct motion parameters in real time.
3. Machine Body
It is the mechanical main body that bears loads, provides support and directly completes cutting work. It is divided into three sections:
1. Basic supporting components: bed, base, column, crossbeam, etc. Most are made of high-strength cast iron or welded steel plates. Some high-end machines adopt new materials such as polymer concrete to guarantee the rigidity and stability of the whole machine.
2. Core moving components: spindle box, feed drive mechanism, tool post, automatic tool changer, etc. Ball screw pairs and rolling guide rails are widely used to shorten the transmission chain and improve precision.
3. Auxiliary devices: lubrication system, cooling system, chip removal system, hydraulic system and pneumatic system, which ensure smooth machining operation.
II. Routine Maintenance of CNC Machine Tools
1. Daily Maintenance (Before and after each shift)
① Motion inspection: Switch to manual mode and check whether the movement of each axis and manual tool change work normally.
② Guide rail cleaning: Wipe X and Z axis guide rails with industrial rags (cotton yarn is forbidden) to remove metal scraps and impurities.
③ Liquid level inspection: Check the oil level of the lubrication tank. Refill oil if it is below the lower limit, and do not exceed the upper limit after refilling.
④ Preheating: Start the spindle without load, gradually increase the rotating speed from low to high. Start machining after 5~10 minutes of warm-up operation.
2. Weekly Maintenance & Periodic Inspection
① Deep cleaning: Remove metal scraps and oil dirt inside the machine, wipe off impurities on guide rails and ball screws.
② Lubrication: Add lubricating oil to guide rails and lead screws, and confirm the automatic lubrication system supplies oil normally.
③ Dust prevention: Clean the ventilation filter screen of the numerical control unit to avoid dust blockage and overheating.
④ Clearance inspection: Check the connection clearance of screw drive pairs and tool magazine manipulators, and adjust preload timely.
3. Environmental Requirements & Long-term Storage Maintenance
① Environmental conditions: Keep the machine away from direct sunlight and vibrating equipment. Maintain a dry, low-dust environment to prevent corrosive gas from damaging electronic components.
② Power supply: Use an exclusive power line or install a voltage stabilizer to avoid excessive power fluctuation.
③ Long-term shutdown: Do not store the machine idle for a long time. Power on and run the equipment 1~2 times every month to keep circuit boards dry and prevent damp damage.
④ Troubleshooting: When a failure occurs, the operator shall keep the scene intact and describe the fault truthfully to maintenance personnel for quick troubleshooting.
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