The key to preventive maintenance of CNC machine tools is to strengthen daily maintenance. The main maintenance work includes the following contents: 1. The main items of daily inspection include hydraulic system, spindle lubrication system, guide rail lubrication system, cooling system and pneumatic system. Daily inspection is based on the normal situation of each tested system. For example, during the process inspection of the spindle lubrication system, the power light should be on and the oil pump should operate normally. If the power light is not on, the spindle should be stopped and contact the mechanical engineer. For maintenance. 2. The main items of weekly inspection are machine tool parts and spindle lubrication system, which should be checked correctly every week, especially the machine tool parts should be cleaned of iron filings and external sundries. 3. The monthly inspection is mainly to check the power supply and air dryer. Under normal circumstances, the rated power supply voltage is 180V-220V, and the frequency is 50Hz. If it is not normal, it must be measured and adjusted. The air dryer should be disassembled once a month, then cleaned and assembled. 4. Seasonal inspection Seasonal inspection should mainly be carried out from three aspects: bed, hydraulic system and spindle lubrication system. For example, checking the lathe bed mainly depends on whether the accuracy and level of the lathe meet the requirements in the manual. If you have any questions, please contact the mechanical engineer immediately. When checking the hydraulic system and the spindle lubrication system, if there are any problems, please replace them with new oil 6oL and 20L respectively and clean them. 5. After half a year, check the hydraulic system, spindle lubrication system and X axis of the machine tool. If there is a problem, replace it with new oil and then clean it. After being fully familiar with and mastering the knowledge of preventive maintenance, we must also have a deeper understanding and necessary grasp of the causes and treatment of abnormal phenomena in the oil pressure system. For example, the oil pump does not spray oil, the pressure is abnormal, and there is noise. We should know what the main reason is and what the corresponding solution is. The causes and treatment of abnormal phenomena in the oil pressure system should be understood from three aspects: (1) The main reasons why the oil pump does not inject oil may include low oil tank level, reverse rotation of the oil pump, low rotating speed, too high oil viscosity, low oil temperature, filter blockage, too large oil suction pipe volume, air intake, shaft and rotor damage, etc. The main reasons have corresponding solutions, such as refueling, confirmation signs, etc. (2) Abnormal pressure means that the pressure is too high or too low. The main reasons are various, such as improper pressure setting, bad action of pressure regulating valve coil, abnormal pressure gauge and leakage of oil pressure system. The corresponding solutions include dismantling and cleaning according to the specified pressure setting value, replacing a normal pressure gauge and checking each system in turn. (3) Noise is mainly generated by oil pumps and valves. The valve is noisy because the flow rate exceeds the rated standard, so the flow rate should be adjusted appropriately; When the oil pump is noisy, there are many reasons and corresponding solutions, such as high viscosity and low oil temperature. The solution is to increase the oil temperature. When there are bubbles in the oil, the air in the system should be released and so on. In a word, if you want to do a good job in preventive maintenance of CNC machine tools.