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How should CNC machining centers perform equipment maintenance before and after the long holiday?

2023/9/26 14:45:17 click:

As we all know, the correct operation and maintenance of CNC equipment can reduce abnormal wear of machine tools and reduce the probability of temporary sudden failures. It can also maintain the processing accuracy and long-term stability of machine tools and extend the service life of machine tools. Therefore, this work must be paid attention to by everyone from top to bottom and implemented resolutely.

The Mid-Autumn Festival and National Day are approaching. In order to ensure that the CNC machining center can operate normally after the holidays and resume production quickly, the following equipment shutdown and maintenance work must be done before the holidays.

1. Clarify the specific person responsible for maintenance;

① Make it clear that operators are responsible for the use, maintenance and basic maintenance of equipment.

② Make it clear that equipment maintenance personnel are responsible for equipment repairs and necessary maintenance work;

③ Make it clear that workshop managers are responsible for supervising various operators and equipment maintenance in the entire workshop;

2. Basic requirements for the use of CNC equipment

(1) CNC equipment is required to avoid places with moisture, dust and corrosive gases;

(2) Avoid direct sunlight and other heat radiation, and keep precision CNC equipment farther away from equipment with large vibrations, such as punch machines, forging equipment, etc.;

(3) The operating temperature of the equipment should be controlled between 15℃-35℃. The precision processing temperature should be controlled around 20°, and temperature fluctuations should be strictly controlled.

(4) In order to avoid large power fluctuations (when the amplitude is higher than plus or minus 10%) and predictable instantaneous signal interference, CNC equipment generally uses dedicated lines for power supply (such as a separate line from a low-voltage power distribution room for use by a separate CNC machine tool) ) Adding a voltage stabilizing device, etc. All the above operations will reduce the impact on power supply quality and electrical interference.

3. Daily processing accuracy maintenance

① After turning on the machine, it must be preheated for about 10 minutes before processing; if the machine is not used for a long time, the preheating time should be extended. Especially when returning to work after the Mid-Autumn Festival + National Day holidays, you should pay special attention to this.

② Check whether the oil line is smooth;

③ Before shutting down, place the workbench and saddle in the center of the machine (move the three-axis stroke to the middle position of each axis' stroke)

④ Keep the machine tool dry and clean

4. Daily cleaning work

① Clean the chips and cutting fluid on the worktable and X, Y, Z axis guards in the machine.

② Clean the chips in the tool magazine, the chips on the tool handle, and the chips and oil on the tool claws.

③ Clean the chips and cutting fluid in the spindle taper hole, and do not install the tool holder on the spindle.

④ If the machine is shut down for a long time, clean the chips in the three-axis guard and the chips and oil on the screw and guide shaft.

⑤ To stop the machine tool, the three and four axes need to be moved to the center position.

5. Lubrication and anti-rust

① Lubricate the transmission parts of the tool magazine and apply grease. Grease: Make sure the grease is of high quality.

② Lubricate the axis of the spindle unclamping mechanism with grease. Grease: Make sure the grease is of good quality.

③ Carry out anti-rust treatment on the workbench and three-axis guard, dry them and apply anti-rust paste.

④ Apply grease to the spindle taper hole. Grease: Make sure the grease is of good quality.

6. Warm up and run dry

Machine tool warm-up: When the machine tool has been parked for a long time, when it is turned on for the first time, warm up the electrical appliances first, turn on the machine power, and release the emergency stop for 20 minutes.

Spindle preheating: Before running the machine tool again after being shut down for a long time, the machine tool must be run dry according to the following steps:

a) Fix the spindle speed at a safe speed of 1000 rpm;

b) Rotate the spindle at 500 rpm for about half an hour;

c) Rotate the spindle at 1000 rpm for about half an hour;

d) Stop the spindle rotation and preheat each axis (X-axis, Y-axis, Z-axis, run at a speed of 12m).

Special precautions

a) After long-term shutdown, the X-axis, Y-axis, and Z-axis must be idle for about half an hour at a speed of 12m/min (12 meters per minute) before running again;

b) If the machine tool is not used for a long time, if the spindle speed is too high, the spindle bearing or chuck hydraulic cylinder may be damaged.

7. Daily maintenance

(1) Clean dust and iron filings on machine tools every day: including machine tool control panel, spindle taper hole, tool car, tool head and taper shank, tool magazine arm and magazine, turret, etc.; XY axis sheet metal guard, machine tool Internal flexible hose, chip chute, etc.;

(2) Check the lubricating oil level to ensure the lubrication of the machine tool

(3) Check whether there is enough coolant in the cooling box and add it in time if it is not enough;

(4) Check whether the air pressure is normal;

(5) Check whether the air blowing into the tapered hole in the spindle is normal, wipe the tapered hole in the spindle with a clean cotton cloth, and spray light oil on it;

(6) Clean the tool magazine, tool arm, tool, and claw

(7) Check all signal lights and whether the abnormal warning lights are normal;

(8) Check whether there is leakage in the hydraulic unit pipe

(9) The machine tool needs to be cleaned after the daily work is completed.

(10) Keep the environment around the machine clean and tidy;

8. Weekly maintenance

① Clean the air filter of the heat exchanger, the cooling pump, and the lubricating oil pump filter;

② Check whether the tool pull bolt is loose and whether the tool handle is clean;

③ Check whether the far point of the three-axis machine is offset

④ Check whether the movement of the tool changer arm of the tool magazine or the rotation of the tool magazine's cutter disc is smooth;

⑤ If there is an oil cooler, please check the oil cooling oil. If it is lower than the scale line, please add oil cooling oil in time;

⑥ Clean impurities and moisture in the compressed gas, check the amount of oil in the oil mist separator, check whether the solenoid valves are working normally, and check the sealing in the starting system, because the quality of the gas system directly affects the tool change and Lubrication system;

⑦ Prevent dust and dirt from entering the CNC device. There is generally oil mist, dust and even metal powder in the air in the machine shop. Once it falls on the circuit boards and electronic devices in the CNC system, it is easy to cause the insulation resistance of the components to decrease, leading to damage to the components and circuit boards.

9. Monthly maintenance

1) Check the lubrication condition of the shaft track, and the track surface must be well lubricated;

2) Check and clean limit switches and bumpers

3) Check whether there is enough oil in the oil cup of the cutting cylinder. If it is insufficient, please add it in time;

4) Check whether the indicator plates and warning plates on the machine are clean and present.

10. Half-year maintenance

① Disassemble the shaft chip guard, clean the shaft oil pipe joint, ball guide screw, and three-axis limit switch, and check whether they are normal. Check whether the hard rail scraper blades on each axis are in good condition

② Check whether the servo motors and heads of each axis are operating normally and whether there are any abnormal sounds;

③ Replace the hydraulic unit oil and tool magazine deceleration mechanism oil;

④ Test the clearance of each axis and adjust the compensation amount if necessary;

⑤ Clean the dust in the electrical box (make sure the machine tool is turned off)

⑥ Comprehensively check whether all contacts, connectors, sockets, and switches are normal;

⑦ Check whether all buttons are sensitive and normal;

⑧ Check and adjust mechanical level

⑨ Clean the cutting water tank and replace the cutting fluid

11. Annual professional maintenance or repairs

(1) Note: Professional maintenance may be performed by professional engineers.

(2) The grounding protection system should have perfect continuity to ensure personal safety

(3) Perform regular inspections of vital parts such as circuit breakers, contactors, single-phase or three-phase arc extinguishers. For example, if the wiring is loose or the noise is too loud, find out the cause and eliminate the hidden dangers.

(4) Make sure the cooling fan in the electrical cabinet is running normally, otherwise it may cause damage to the vitality parts;

(5) The fuse is blown and the air switch trips frequently. The cause should be found and eliminated in time.

(6) Check the vertical accuracy of each axis and adjust the geometric accuracy of the machine tool in order to restore or meet the requirements of the machine tool. Because geometric accuracy is the basis of the overall performance of machine tools. For example: poor perpendicularity of XZ and YZ will affect the coaxiality and symmetry of the processed workpiece, poor verticality of the spindle to the table will affect the parallelism of the processed workpiece, etc. Therefore, the restoration of geometric accuracy is the focus of maintenance.

(7) Check the wear and clearance of the motor and screw rod of each axis, and check whether the support bearings at both ends of each axis are damaged. When the coupling or bearing is damaged, it will increase the noise of the machine tool operation, affect the transmission accuracy of the machine tool, damage the screw cooling seal ring, cause cutting fluid leakage, and seriously affect the life of the screw and spindle.

(8) Check the protective cover of each axis and replace it if necessary. A poor protective cover will directly accelerate the wear of the guide rail. If there is large deformation, it will not only increase the load on the machine tool, but also cause greater damage to the guide rail.

(9) During routine inspections, the procuratorate will first place the screw rod in its natural state, and then install the screw rod in accordance with the maintenance procedures to ensure that the screw rod does not exert tangential force as much as possible during movement, so that the screw rod is also in a stable state during processing. state of nature;

(10) Check and adjust the belt drive system of the machine tool spindle, adjust the tightness of the v-belt appropriately to prevent the machine tool from slipping or losing rotation during processing, replace the spindle v-belt if necessary, and check the pressure pulley cylinder for high-low gear conversion of the 1000r/min spindle The amount of oil. Add it when necessary. Lack of oil will cause failure during low-speed switching, seriously affect the surface roughness during milling, and reduce the cutting torque.

(11) Cleaning and adjustment of tool magazine. Adjust the rotation of the tool magazine so that it is parallel to the table, replace the circlip if necessary, adjust the angle of the spindle directional bridge and the rotation coefficient of the tool magazine, and add lubricating grease to each moving part.

(12) Prevent system overheating: You should check whether each cooling fan on the CNC cabinet can work normally. Check whether the air duct filter is clogged. If too much dust accumulates on the filter and is not cleaned in time, it will cause the temperature inside the CNC cabinet to be too high.

(13) The input and output devices of the CNC system also require regular maintenance. For example, regularly check whether the transmission signal of the machine tool is damaged, whether the screws and nuts of the interface connector are loose and fallen off, whether the network cable is firmly inserted, cleaning and maintenance of the router, etc.

(14) Regular inspection and replacement of DC click brushes. Excessive wear of the DC motor affects the performance of the motor and may even cause damage to the motor. For this reason, motor brushes should be inspected and replaced regularly, and CNC lathes, CNC milling machines, and machining centers should be inspected once a year.

(15) Regularly check and replace storage batteries.