Maintenance & Troubleshooting of CNC Turret Punch: How to Do It Well?

1. Main uses and characteristics of CNC turret punch

CNC turret punch is the most viable integrated machine, electric and hydraulic product in pressure processing equipment.

It is an efficient and precise plate processing equipment controlled by CNC system, which can automatically complete a variety of complex pass and shallow deep drawing molding processing at one time.

Through automatic programming, the plates can be accurately positioned in the X and Y directions, and the molds in the rotary table mold library can be automatically selected for automatic processing according to the requirements.

Small punching dies can also be used to punch large round holes, square holes, waist holes and curve contours of various shapes in the way of step punching, and special process processing can also be carried out, such as louvers, shallow stretching, counterbores, flanging holes, stiffeners, embossing, etc.

CNC turret punch

2. Use requirements of CNC turret punch

1. Operating environment

In order to improve the service life of CNC turret punch press, it is generally required that the room temperature should not be too high.

Direct sunlight and other thermal radiation should be avoided, and places with too much moisture, dust or corrosive gas should be avoided.

Keep away from high-frequency and electromagnetic equipment, such as hydrogen arc welding machine, electric welding machine, etc.

2. Power requirements

Special lines are generally used for power supply.

In order to avoid large fluctuations and high-order harmonics in the power grid, three-phase AC voltage stabilizing devices are generally equipped to reduce the impact of power supply quality and electrical interference.

The starting end of the power supply is well grounded.

The three-phase power supply entering the CNC turret punch press should adopt the three-phase five wire system.

The neutral line (N) and grounding (PE) should be strictly separated, and the protective grounding should be done well.

3. Operating procedures

In the use and management of CNC turret punch, practical and effective operating procedures should be formulated.

For example, lubrication, maintenance, reasonable use and standardized shift system, formulating and abiding by operating procedures is one of the important measures to ensure the safe operation of CNC machine tools.

Practice has proved that many faults can be reduced by observing the operating procedures.

4. Personnel requirements

The operator of CNC turret punch should be specially trained and qualified before operating the equipment, otherwise it may cause damage to the machine tool and even endanger personal safety.

Such lessons have been many and should be borne in mind.

The personnel operating the equipment shall be stable, skilled and master the equipment conditions as far as possible to ensure the stable operation of the equipment.

5. Routine maintenance

Daily maintenance can keep the CNC punch in good condition and prolong the service life of the machine tool.

At the same time, hidden dangers can be found and eliminated in time, so as not to cause heavy losses.

6. Dynamic storage of numerical control equipment

After purchasing the CNC turret punch, we should make full use of it, especially in the first year of operation, so that its weak links that are prone to failure can be exposed as soon as possible, so as to eliminate it within the warranty period.

When there is no addition task, the CNC turret punch should also be powered on regularly, preferably once a week, in order to reduce the humidity in the machine by using the calorific value of the machine tool itself, so that the electronic components will not be affected by moisture, and at the same time, it can also detect the alarm of insufficient battery power in time, so as to prevent the loss of the parameters set by the system.

3. Maintenance of CNC turret punch

(1) Keep the surrounding of the machine tool clean and free of sundries.

The surface of the machine tool should be scrubbed regularly to ensure that the surface is free of oil stains and the workbench is free of debris.

The moving surfaces such as lead screws and guide rails are cleaned once a week.

Clean up the waste materials around the turntable in time to prevent the lower plane of the lower turntable from being scratched, scratched, and material inclusion and collision.

(2) Do a good job of lubrication and ensure that all lubrication pipelines are unobstructed.

Regularly check the centralized lubrication device and hydraulic station to ensure that the oil level is high and the oil quality is good.

Drain the air compressor every day, drain the water distributor equipped on the machine tool, and check the oil level of the oil mist to ensure that there is enough oil to effectively lubricate the air pipeline.

(3) Check the mold regularly to prevent damage to the mold due to wear of the die opening or guide key.

(4) During the operation of the machine tool, it is not necessary to press the “emergency stop” button under non emergency conditions, especially when using the rotating die.

(5) It is forbidden to pull the synchronous belt of the rotary die by hand to avoid the dislocation of the C-axis.

(6) Regularly check the dust on the components in the electrical cabinet, especially the module with cooling fan, and clean it at least once a month.

Baote electric control cabinet is dry and clean.

(7) Check the hydraulic components and pneumatic components for oil and air leakage.

4. Typical fault analysis and troubleshooting of CNC turret punch

1. Strip failure

Due to insufficient material returning force, the punch fails to withdraw from the sheet when the die goes up, or the continuous stamping time is not well matched, and the die goes up with the sheet.


① Spring fatigue;

② The timing of stepping and punching is not well matched;

③ The cutting edge of the upper die is fused, causing wear;

④ Unreasonable clearance;

⑤ Poor lubrication of mold;

⑥ The cutting edge of the lower die is worn.


① Replace the spring;

② Adjust the step length;

③ Prevent the upper mold from melting and burning, and use multiple molds of the same specification to rotate or replace the punch material;

④ Select the mold with corresponding clearance according to different plate thickness and materials to ensure the alignment of the mold during blanking;

⑤ Clean the mold frequently and keep it well lubricated;

⑥ Grind the lower die in time, keep the lower die sharp, and have a small arc at the right angle of the blade.

2. Waste rebound fault

In the punching process, the upper die brings the blanking after the hole out of the lower die.


① There is oil on the upper surface of the plate or the bottom surface of the die, causing the waste to adhere to the punch, and the waste is brought up;

② The mold (or sheet) is magnetic;

③ The stamping speed is high and the return stroke is fast, forming its empty effect;

④ The previously washed waste is stuck in the lower die, forming an air tight cavity, and the waste is rebounded;

⑤ The height of the mold is incorrect;

⑥ Blunt for mold;

⑦ Die clearance value is too large;

⑧ Aluminum plate or stainless steel plate with film;

⑨ The unloading bar used is aged or damaged.


① Remove the oil stain on the plate surface, and the pushing rubber column on the end face of the punch should be replaced in time without missing;

② The die is completely demagnetized after grinding;

③ Reduce stamping times appropriately;

④ Properly increase the modulus, generally ≥ 1mm;

⑤ When there is a vacuum suction device, check whether the vacuum system is normal;

⑥ Sharpen the mold in time to keep the edge sharp;

⑦ Select the lower mold with appropriate clearance;

⑧ Use the lower mold to prevent the waste from bouncing.

3. Rotary table dislocation fault

When the CRT gives an alarm that the t-pin is not in or the pin is not in, the rotary table shakes.


After the machine is used for a period of time, the dislocation of the rotary table positioning pin relative to the rotary table positioning hole caused by the deformation of the chain or other reasons is very likely to occur.

Sometimes, the upper and lower rotary tables may be misaligned, and sometimes there may be only one rotary table misaligned.

No matter what happens, the adjustment method is the same.

Adjustment method:

Power on;

Set the machine to manual operation position;

Press the pin out button to exit the locating pin;

Loosen the screws that fix the end cover of the drive shaft sprocket so that the drive shaft and sprocket can rotate relatively;

Manually move the rotary table to align the locating pin with the locating pin hole of the rotary table;

Press the pin in and pin out buttons repeatedly to check whether the pin is aligned with the rotary table. After adjustment, pin the pin;

Before adjustment, check the tightness of the chain. If the chain is loose, tension the chain first, and then adjust the alignment of the locating pin.

When the tension of both sides of the chain is close to the same, fix the fixing sleeve of the sprocket;

Finally, return to automatic mode.

4. Hydraulic system failure

In case of 1050 alarm, the punch is not at the top dead center, and the X-axis, Y-axis and T-axis cannot act.

(model vt-500, CNC system FANUC oi–p ℃: hydraulic system is doctor Rexroth).

After this fault occurs, checking the maintenance technical data only indicates that the main hydraulic pump is not on, and there is no other prompt, but the oil pump has been started normally.

The disadvantage of the hydraulic system is that the oil temperature is high, and the temperature of the 4wrse same service valve is also high.

It is likely that the servo valve is faulty.

Because the valve is not good for split inspection, it is difficult to judge whether it is good or bad.

First, check whether the voltage at both ends of the power supply a and B of the intermediate service valve is 24V, whether the plug of the same service valve is plugged in, and whether the operation light and power light of the HNC control card are normally on.

Normally, when the oil pump is turned on, the punch should move a few millimeters, and whether the oil pressure changes between the set values.

Whether the data bus plug between HNC control card and CNC system is well connected.

If necessary, open the plug shell and check whether the wiring is good.

Check the top dead center PTE signal, which can enter the self diagnosis function.

The sequence is SYS TEM/PMC/PMCDGN/STATUS/ input X8, and the corresponding x8.2 must be 1.

Check whether the voltage of the signal from HNC100 between wire numbers 411 and 100 is DC24V, and between wire numbers 612 and 100, and the voltage must also be DC24V.

If there is no problem after the above inspection, you can use Win-ped5.05 software to further connect the HNC control card for diagnosis and check various parameters.

If there is no problem, you can judge that the service valve has mechanical failure, and you can replace the valve for test.

If the problem is solved, the failure is the damage of the service valve.

After the above inspection, the fault cannot be eliminated.

It is best to contact the manufacturer.

5. Faults related to punch vibration

(1) In the stamping process, stop the pressure, the system will restart automatically, and it can work normally again.

This fault occurs repeatedly in the stamping process without alarm prompt. It is difficult to find the cause of the fault in normal conditions.

Most of this fault is related to vibration.

If the three-phase voltage is checked to be stable, it is generally because the DC24V voltage of each valve or induction switch has an instantaneous short circuit, causing a voltage drop and causing the system to restart.

Because of the rapid stamping of the CNC punch, the high-frequency vibration is easy to cause the DC24V power line of each valve and induction switch to be damaged or the wiring to be loose, causing the short circuit to the ground between Shun and shun. Such problems have been encountered many times in the actual maintenance.

This kind of fault requires the maintenance personnel to check carefully one by one, focusing on the signal lines around the turret.

(2) In the continuous stamping process, it often stops for about 2S and continues to work, without fault alarm.

Such faults are mostly related to vibration, especially the thicker the punching plate is, the more likely it is to appear, that is, the greater the vibration is, the more likely it is to appear.

After careful observation, it was found that the instrument pointer on the air pressure triplet fixed on the bed exceeded the set value of the minimum air pressure due to the vibration amplitude.

Cause the instantaneous air pressure alarm and stop, separate the air pressure triplet from the punch bed, and eliminate the fault.

5. Conclusion

To make the CNC turret punch achieve high efficiency and good effect, it all depends on the quality of operators and Weiyou personnel, who should have a high sense of responsibility and good professional ethics.

The operator should be familiar with the performance of the machine tool, operate and maintain it in strict accordance with the regulations, and pay attention to the maintenance work, especially the cleaning and lubrication of the machine tool.

Maintenance personnel should not only pay attention to analyzing problems and accumulating experience, but also be diligent in learning, good at learning and good at thinking.

Through the appearance of the fault, they should think and analyze various possible causes of the fault, so as to quickly find out the root cause of the fault and eliminate it.

Do “use your brain and hands carefully”, and avoid hasty conclusions and blind replacement of components.

In short, good maintenance is the effective preventive measure to avoid failures, and it is also the best policy.

Instead of taking time to study repair, it is better to take time to do good maintenance.

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