10 CNC spindle common faults and troubleshooting methods revealed

The machine tool spindle is composed of a variety of accessories, such as spindles, bearings, transmission components (gears or pulleys), etc. However, some failures will inevitably occur over time.

The machine tool spindle, as one of the core components of CNC machine tools, mainly refers to the machine tool to drive the workpiece or tool rotation of the axis. Usually working in high humidity, dust, temperature differences, and other working environments, one not only needs to "day and night," but also needs to ensure the machining accuracy and precision. A machine tool spindle is usually composed of a spindle, bearings, transmission parts (gears or pulleys), etc., which is an important guarantee of CNC machine tool finishing, but time will inevitably have some failures. Therefore, the spindle repair method is a CNC machine tool that operators and maintenance personnel must master.

Spindles in practical applications are mainly divided into two categories: one is a high-speed electric spindle with zero transmission, and the other is a variable frequency spindle motor combined with a mechanical variable speed mechanism of the spindle. The former has an integrated structure with the motor, and after accurate dynamic balance calibration, although it has good rotary accuracy and stability, its output torque and power are limited; the latter's output torque and power are not too restricted, but its rotary accuracy and smoothness are relatively poor.

Therefore, the common CNC spindle faults generally have spindle parts damaged, spindle box and bed between the bolt loosening, drive belt loosening, oil pump steering is not correct, oil pipe clogging, hydraulic valve damage, damage to the electrical components, control system no detection signal, etc., and their corresponding solutions can be subdivided into the following ten categories:

Ⅰ. The spindle without a brake

Abnormal braking circuit or strong circuit components are damaged; check whether the bridge stack, fuse, or AC contactor is damaged; Check whether the strong electric circuit is disconnected.
The braking time is not long enough; adjust the braking time parameter of the system or frequency converter.
no braking signal output from the system: replace the internal components or send it to the factory for repair.
The control parameters of the frequency converter are not adjusted properly; consult the instruction manual of the frequency converter and set the parameters of the frequency converter correctly.

Ⅱ. The spindle stops immediately after starting

>The system output pulse time is not enough. adjust the system M code output time.
>The frequency converter is in the point state. Refer to the instruction manual for the frequency converter, set the parameters.
damage to the control components of the spindle circuit: check whether the contacts on the circuit contact are good; check whether the DC relay, AC, or contactor is damaged, resulting in contacts not self-locking.
pindle motor short circuit, resulting in thermal relay protection: find the cause of the short circuit so that the thermal relay resets.
The spindle control circuit does not have a self-locking circuit, and the parameters for the pulse signal output are set so that the spindle can’t run normally. The system controls spindle start-stop parameters in level control mode.

Ⅲ. The spindle rotation can’t stop

The AC contactor or DC relay is damaged and can’t be controlled because of long time absorption. Replace the AC contactor or DC relay.

Ⅳ. The spindle rotates immediately when the system is powered on

The AC contactor or DC relay is damaged, long-absorbing, and can’t be controlled. Replace the AC contactor or DC relay;
system IC2803 breakdown: replace the IC2803 or system motherboard.

Ⅴ. Without frequency conversion, spindle does not turn

caused by mechanical transmission faults: check whether the belt drive is broken or whether the machine is in neutral gear;
three-phase power supply to the spindle phase or phase reversal: check the power supply, replace any two power lines;
incorrect circuit connections: refer to the circuit connection manual carefully to ensure correct connections;
The system has no corresponding spindle control signal output; use a multimeter to measure the system signal output, if there is no spindle control signal output, you need to replace the relevant IC components or send them to the factory for repair;
The system has a corresponding spindle control signal output, but between the power supply line and the control signal output line, there is a broken circuit or component damage. Use a multimeter to check the system and the spindle motor between the power supply circuit and the signal control circuit to see if there is a broken circuit; whether there is a broken circuit; whether the contact between the line contact is poor; the AC contactor and DC relay to see if there is damage; check whether the thermal relay is overcurrent; Check whether the fuse is burned, etc.

Ⅵ. The spindle with an inverter does not turn

It may be caused by mechanical transmission failure: check whether the belt drive is broken or whether the machine tool is in neutral gear;
Three-phase power supply to the spindle phase: check the power supply and replace any two power lines;
The frequency converter control parameters of the CNC system are not open. Consult the system manual to understand the frequency conversion parameters and change them.
The system and the frequency converter line connection error: check the system and the frequency converter connection instructions to ensure that the connection is correct;
Analog voltage output is not normal: use a multimeter to check whether the analog voltage output from the system is normal. Check whether the analog voltage signal line is connected correctly or has poor contact, and whether the analog voltage received by the frequency converter is matched.
The strong electric control part is broken or the components are damaged. Check whether the contacts of the spindle power supply line are connected reliably, whether the line is broken, whether the DC relay is damaged, and whether the fuse is burned out.
Frequency converter parameters are not adjusted: the frequency converter contains control mode selection, divided into frequency converter panel control spindle mode, NC system control spindle mode, etc. If you do not select the NC system control mode, you can’t use the system to control the spindle. Modify this parameter; check whether the relevant parameter settings are reasonable.

Ⅶ. Inverter-controlled spindle speed is not controlled

The main board used has no frequency conversion function: replace the main board with a frequency conversion function.
The analog voltage of the system has no output; check that the relevant parameter settings are reasonable.
The system analog voltage output or connection with the frequency converter has a broken circuit: first check the system analog voltage output; if not, then the system failure, if so, check the line to see if it is not a broken circuit.
The system and the frequency converter connection line are not broken circuit.
System and inverter connection error: consult the connection manual; check the connection.
System parameters or inverter parameters are not set. Open the system frequency parameters and adjust the inverter parameters.
The system software caused by the shaft speed display is not correct: when the frequency converter is from S500 to S800 but the display is still S500, you need to use the G04 delay in programming, pending system software improvement.

Ⅷ. Without frequency conversion, spindle (shift spindle) speed is not controlled

The system does not have S01-S04 control signal output: check that the system has no gear shift control signal output. If not, it is a system failure, replace the IC or send it to the factory for repair.
connection line failure: if the system has a shift control signal output, then check the connection line to see if there is a broken circuit or poor contact, check whether the DC relay or AC contactor is damaged.
spindle motor damage or short circuit: check the spindle motor.
mechanical not in gear: hang up the gear.

Ⅸ. With electric coupling, the spindle does not turn

Electromagnetic clutch coils have no voltage supply, so the transmission gear can't be closed, resulting in the spindle not being able to rotate. coil short-circuit, disconnection may also lead to the spindle not working properly. Check that the clutch coil power supply is not normal; fuse is not damaged. Check that the clutch coil is not damaged, replace the components in line with specifications.

X. The spindle does not rotate while holding the brake coil

Electromagnetic clutch coils have no voltage supply, so the transmission gear can’t be closed, resulting in the spindle not rotate; coil short-circuit, disconnection may also lead to the spindle not work properly: Check that the clutch coil power supply is not normal; fuse is not damaged. Check that the clutch coil is not damaged, replace the components in line with specifications.

Conclusion

In summary, in the CNC machine tool repair work, because of the complexity of the cause of the failure, the repair law should be: first of all, list the reasons that may cause the failure according to the main draw up feasible troubleshooting program; and then, determine the general failure of the site before the maintenance of the hands. Overall, CNC machine tool spindle failure is relatively common. As long as the mechanical structure of the spindle is analyzed and the cause of the failure, maintenance and troubleshooting, you can ultimately make the spindle to restore the normal work of the machine tool!