Guide to Troubleshooting Spindle Drives 

In every industrial facility, operators face tough decisions from time to time regarding the state of certain machines, parts, tools and devices. In the midst of forecasting overhead budgets and mulling over profit margins, a machine part might suddenly show symptoms of irregularity. When it comes to a crucial part of the manufacturing line, such as the spindle drive, you might find yourself wondering whether it is time to replace the item in question, or if spindle drive troubleshooting tips will solve the issue or help to get the drive repaired.

DIY spindle drive repair is not always possible, especially not when the problem is too far out of hand. If the parts are really worn and aged, there won’t be much left to salvage you may need to send it out for professional repair.  After all, if you continue to use a faulty spindle drive, the impact on your productivity could severely undercut your bottom line.

All things considered, spindle drive troubleshooting tips can help you save money when the problem is minor and easily reversible. In some cases, the problem can be fixed with minor tinkering, as long as you catch the problem early. In other cases, the issue might require more skill and know-how to rectify properly, but the troubleshooting steps can ultimately be effective as long as you have the knowledge and necessary tools on hand.

Common Spindle Drive Problems and Troubleshooting Suggestions

The following list details common problems with spindle drives, some of which can be remedied with a bit of troubleshooting and others that indicate a need for parts replacement and professional repair.

#1. Parameter Settings

On Wye/Delta-wired machines, determine that the bounds are placed at high torque. This creates a dwell angle of roughly one second, which enables the Wye/Delta Contractors to flip into place in advance of spindle activation. The delay that this creates lessens the possibility of contractor arcing.

Additionally, the insertion of this parameter enables a post-shifting range dwell that precedes the commanding of a spindle. The additional time makes it possible for the more sluggish hydraulic idlers to become engaged in full. However, if the setting is off, the belts could possibly chirp when the spindle is activated.

#2. Main Power Disconnect

Inspect the fuses. If the fuses are worn or expired, replace them with new ones. Even if the fuses appear to be in good shape and seem capable of handling voltage, it does not mean that the fuses will be able to supply the necessary current.

Clean the contacts of the blade engagement. If corrosion is present, remove it with the proper formula. If the connection is poor, it could cause DC low errors that might ultimately prevent the motor from achieving maximum rotations per minute.

#3. Transformer

A target input voltage of 230 VAC is required for the spindle drive. If the voltage exceeds this limit, it could cause DC high errors or resistor failure at the braking registration. If the voltage falls under the required amount, DC low errors will result.

#4. Drive Input Power Connections

If the connections are slack or in any way poor on the L1 L2 L3 GND, phase loss issues and low DC errors are liable to result. In these cases, the motor will not be able to achieve maximum rotations per minute.

#5. Breaking Resistor

If the connection is worn, loose, open or simply wrong, it can result in high DC errors during the deceleration phase of operation. To correct and determine the origin of the problem, remove the REGEN wires and inspect the resistor’s OHM value. If the value is zero, or open, there lies the root of the problem.

#6. Spindle Encoder

With a vector drive, the output current is impacted by the encoder. Therefore, the encoder must be tested to ensure it works properly.

#7. Motor Connections

Inspect the connections on both sides of the motor. If looseness is present at the T1 T2 T3 GND of the drive, or at the Wye/Delta connectors, problems such as overcurrent will result. One of the most frequent causes of faulty diagnosis in this area is impedance — defined as the opposition to electrical current flow in a conductor.

If the motor does not receive the necessary electric current, it loses torque. The current is especially crucial to the stability of motor control with a Vector drive. The drive wires that carry circuits to the motor must supply the correct level of current and voltage. In some cases, a mega ohm test might work.

#8. Junction Box

Check all of the motor’s 12 lead connections. If any of them are loose, faults with the current are liable to result. One piece that is known to be problematic is the bolt-clamp connector of the motor, which is prone to wear down and is likely to inflict random shorts. The wires should also be checked for traces of wear, which can form along the insulation as the result of friction rubbing.

On certain drive systems, the junction box will contain a terminal block to enable motor connections. This type of system is known for high impedance.

#9. Wye/Delta Contactors

For all machines with Wye/Delta contractors and for all machines that run 7500 rotations per minute — if the contactors are aged or pitted, replace them. Once they have corroded, the problem cannot be rectified with sandpaper because the light silver plating would only be damaged further. When faults with the spindle emerge as the machine ages, the contactors are the first things that should be replaced.

Aside from the arcing and pitting of the contacts, problems might be found with the electromagnet system, which is liable to wear out with age. Whether or not you can even hear the sound, it will be problematic for the drive. Moreover, the parameters of the drive table could be randomly switched by the contactor micro switch, even though the contactors don’t actually switch. Consequently, the spindle drive could be using incorrect motor parameters.

#10. 1100-1 CNC Board — Only on Wye/Delta

On the Wye/Delta board, the contractor is under the control of the Solid State Relays (SSR). The high range SSR is Relay K27 – F30 (VMC 15), which switches the contactors and keeps them in place by activating the coils within each contractor. The SSR board will eventually fail if it lacks gold plating, in which case, a new SSR will be necessary.

#11. Speed Signal

The 1010 spindle controller is the card that is responsible for the speed of the spindle. The speed is controlled by a 10-volt DC signal. To test the variants of the spindle speed, use the M49 code, which halts the override potentiometer. The voltage is equal to the rotations per minute, and is supposed to be reliably steady.

#12. Drive Enable

The drive of the machine is enabled with FWD and REV relays, which command the direction of the 1100-2 board. To facilitate the drive, the two relays are shut with Rigid Tap. The direction of the rotation is activated by the ±10 VDC signal.

By contrast, with Non-Rigid tap, one relay is shut for forward rotation, and the other relay is shut for reverse. Here, the direction of the rotation is activated by the 0-10 VDC signal. If the relays fail, replace with new ones or change-out with pre-used working relays.

#13. Motor Rewinds

On Closed Loop Vector drives, the motor might turn back and forth following the replacement of a spindle motor with a rewound motor. In cases like these, swap the T1 and T2 of the motor to re-sink the order of rotation. For a drive that lacks an encoder, swap the T1 and T2 while the motor spins in the reverse direction.

#14. 1010 Spindle Controller

In the 1060 motherboard, the spindle card in the #14 slot controls the following functions of the spindle:

• Speed command, indicated by a 10-volt DC signal. On Rigid Tap machines — ±10 VDC. On non-Rigid Tap machines — 0-10 VDC. The voltage is equal to the rotations per minute and should always be steady.
• Orientation magnet, which has the same input signal as the primary CPU, and is also used for calibration and to detect overload errors in the motor.
• Spindle fault, which reports to the CPU any fault lines with the spindle drive.

#15. Motor Test

In order to conduct the motor test, you must first disconnect the T1, T2 and T3 motor wires from the drive. The test can be conducted with a Mega Ohm meter of at least 1000 VCD, which will determine the presence of shorts within the insulation of the motor and wires. The quality to look for is consistency across the three legs. With the reading of the motor at 500 meg or below, test the motor at the following points:

• Test each of the T1, T2 and T3 leads of the motor. The purpose of these tests is to gauge the path between each output of the drive to the contactors, along the junction box and windings of the motor. Perform each test in high and low ranges of the WD configuration.
• Test the six motor winding coils, which can be found within the motor.

#16. Wiring

Determine that the connectors and wiring are sending the proper currents, but steer clear of the internal wiring as you carry out this step. To verify whether a problem exists, you might need to test more than just the Ohm or Mega Ohm. To perform a bypass test, you must run an external wire between the outputs of the motor — T1, T2 and T3 — and straight to the junction box, without touching the inner wiring. For the test to work, the testing wire must match the gauge of wiring used within the machine.

To verify whether the legs of the motor have uniform currents, make current measurements with an AC probe as the motor runs. The legs need to be uniform within two amps. If the current is off-balance when the internal wires are bypassed, the motor likely has issues.

Once you have completed this test, put the internal wiring back into place and inspect the wires and connecting points that join the spindle motor and drive. When testing a 7500 Wye/Delta machine, take the Hi/Low contactors into account. Inspect the amperage of the drive itself and at the connecting points of the motor wire.

#17. Drive Bypass

The drive can be bypassed if you supply the motor with a 230 VAC 3 phase device. By steering clear of the drive, you can more easily verify whether the motor and its wiring are in good shape. Take out the spindle belt or disengage the air supply and draw back the two idlers. Disconnect the motors and power-input wires — T1, T2 and T3 for the motor and L1, L2 and L3 for the power — from the spindle drive. Take the motor wires and connect them directly to the input of the 230 VAC 3 phase.

Upon activation, the motor will immediately spin at 1760 rotations per minute. It is not necessary to activate the CNC with the green button because the CNC will activate on its own. To verify that each of the legs of the motor share a uniform current, take an AC amp probe to gauge the motor current. All of the legs must be uniform within two amps. If one of the legs is out of balance with the others, the problem is likely down to improper wiring or faulty connections.

If the high/low contactors are worn, they need to be replaced. Inspect the amperage between the circuit and the wiring.

Professional Spindle Drive Repair 

No matter what issue might arise with the spindle drives in your industrial machinery, any such problem should be examined upon the first signs of irregular performance. If the problem is small and detected early, spindle drive troubleshooting will work in many cases as long as you know which parts to inspect and have the proper tools on hand.

In some cases, however, spindle drive repair should be handled professionally, because the problems are too advanced, and you would actually save time and money by investing in having it refurbished. Often times, when a spindle drive declines in performance, the problem is simply due to age and the fact that nothing is built to last forever. So having it professionally repaired where weak and aging components get replaced is the best solution.  If you have an issue with a spindle drive, regardless of whether you even know what the issue is stemming from, chances are you should have the drive professionally tested and repaired before you have to make the choice of spending at least double the cost and replacing the drive.

At Global Electronic Services, we fix a wide variety of the kinds of drives and motors used at industrial facilities as well as any industrial electronics. If your company has equipment that needs to be repaired, our service specialists can diagnose the problem and make the proper repairs or recommendations. To find out more about our repair services and surplus solutions, contact Global Electronic Services.