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Preventive maintenance of CNC equipment

Preventive maintenance is to pay attention to the factors that may cause equipment failure and are difficult to solve after the failure before the failure occurs.Generally speaking, it should include: the selection of equipment, the correct use of equipment, and roving inspections in operation.

①The selection of CNC equipment from the perspective of maintenance

In the research on the selection of equipment, in addition to the availability parameters of the equipment, the maintainability parameters should include: the advanced, reliable, and maintainable technical indicators of the equipment.Advanced refers to the technical content of the equipment that must have the level of development of the times; reliability refers to the average trouble-free time and average failure rate of the equipment, especially whether the control system has passed the quality inspection assessment of the national authority, etc. ; Repairability refers to whether it is easy to repair, whether there is a good spare parts market purchase space, whether the technical information for various repairs is complete, whether there is good after-sales service, whether the maintenance technical capabilities are available, and whether the equipment performance and price ratio are reasonable.Here, special attention should be paid to the integrity of the drawing data, the backup system disk, the PLC program software, the system transmission software, the means of transmission, the operation password, etc., which are indispensable.The technical training of the user cannot go through the motions. These must be specified and carefully implemented in the order contract, otherwise it will bring consequences to future work.In addition, if it is not a special case, try to choose the same series of CNC systems from the same company, so that spare parts, drawings, and materials are required.Programming and operation are both beneficial, but also conducive to equipment management and maintenance.

②Adhere to the correct use of equipment

The correct use of CNC equipment is the key to reducing equipment failures and prolonging service life, and it occupies a very important position in preventive maintenance.According to statistics, one-third of all failures are caused by humans, and general maintenance (such as oiling, cleaning, inspection, etc.) is carried out by the operator. The solution is to emphasize equipment management, use and maintenance awareness, strengthen business and technical training, and improve the quality of operators so that they can master the performance of machine tools as soon as possible, strictly implement equipment operating procedures and maintenance procedures, and ensure that the equipment is operating in a reasonable working state.

坚持Adhere to the roving inspection in the operation of the equipment

According to the advanced nature, complexity and high intelligence of CNC equipment, its maintenance and maintenance work is much more complex and demanding than ordinary equipment.Maintenance personnel should pass regular inspections, such as the operation of the exhaust fan of the CNC system, whether the cabinet and motor are heating up, whether there is abnormal sound or odor, whether the pressure gauge indicates whether it is normal, whether the pipelines and joints are leaking, whether the lubrication condition is good, etc., and actively do a good job of fault and accident prevention. If abnormalities are found, they should be resolved in time, so that it is possible to eliminate the fault in the state of Mengya, which can reduce all unavoidable losses.

Examples of CNC equipment maintenance

1.Fault diagnosis of CNC system

①system self-diagnosis

Generally, CNC systems have a relatively complete self-diagnosis system. Whether it is a Fanuc system or a Siemens system, it can make limited self-diagnosis of itself or the interface during power-up initialization or operation.Maintenance personnel should be familiar with various alarm information for self-diagnosis of the system.Analyze according to the manual to determine the fault range.For locating faulty components, imported CNC systems can generally only be located at the board level.

②The soft failure of the CNC system

The soft failure of the CNC system refers to the system software and PLC program of the control system.Some systems write them in EPROM and plug them into the motherboard, and some live on the hard disk.Once there is a problem with these software, the system will cause all or part of the confusion. When the analysis determines that it is a software failure, the spare software or spare EPROM should be used to replace it, and the operation steps should be strictly followed after initialization and trial operation.Such failures are generally not difficult to recover as long as there are backup files.The difficulty lies in the incomplete backup software, the lack of dedicated transmission equipment, or the confidentiality of passwords set in the manufacturer’s operating methods, which cannot be restored due to factors such as incomplete backup software, the lack of dedicated transmission equipment, or the manufacturer’s operating methods.

③Use PLC program to locate the interface failure between the machine tool and the CNC system

Nowadays, general CNC control systems are equipped with PLC controllers, most of which are built-in PLC controls.Maintenance personnel should analyze the machine tool control appliances according to the ladder diagram, and visually see the status of the CNC system I/O on the CRT.Through the logical analysis of the PLC program, the parts of the problem can be easily checked.Such as the self-diagnosis page in the FANUC-OT system, the T command in the FANUC-7M system, etc.

2.Troubleshooting steps

①The reason for the operator’s failure is asked

When a failure occurs, maintenance personnel generally do not rush to do it. They should carefully ask what working state the bed was in when the failure occurred, its manifestations, the consequences, and whether it was a misoperation.Whether the fault can be reproduced, etc.

②facial and basic power supply inspection

Mainly observe whether the equipment has abnormal conditions, such as mechanical stuck, motor burned out, insurance fuse, etc.First check whether the AC\DC power supply is normal and narrow the fault range as much as possible.

③Analyze the drawings and determine the fault site

Analyze the ladder diagram according to the drawings to determine whether the fault site is a mechanical, electrical, hydraulic or pneumatic failure.

④Expand your thinking and analyze based on experience

According to empirical analysis, we must expand our thinking, not limited to the scope of the maintenance manual. The maintenance information only provides one idea, which is sometimes very limited.For example, a FANUC—OT CNC lathe in our factory has no screen on the CRT after it is turned on, and the alarm indicator light of the power module is on. According to the maintenance manual, it is found that the 24EDC power supply common to the CRT and I/O interface has only 1—2Ω resistance between the positive terminal and the DC ground, while similar equipment uses 155Ω resistance. According to the information, this kind of failure is generally on the motherboard and can only be sent to the manufacturer for repair, and we expand our thinking, first unplug the Ml8 cable plug, the fault is still there, and then unplug the C-Sl4 plug. There is a short circuit phenomenon, after troubleshooting. , The machine tool returned to normal.

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