Pallet Wrapper Turntable Not Turning
A turntable that won't rotate is usually a drive fault, a mechanical obstruction under the table, or a brake that isn't releasing. Whether it stops immediately or won't start at all tells you where to look first.
Common symptoms
Note whether the turntable moves at all, whether it stops partway through a cycle, and whether the display shows a fault code. Each combination points somewhere different.
Turntable doesn't move at all on start
No rotation at all when the cycle starts usually means the drive isn't receiving a run signal, a brake isn't releasing, or the drive has tripped. Check the display for a fault code first - the drive will often log exactly what stopped it.
Turntable starts then stops mid-cycle
A mid-cycle stop that repeats at the same load weight or at the same point in the wrap often means the drive is overload-tripping. Either the load is too heavy for the speed setting, or there's a mechanical drag that's been building gradually.
Rotation is slow or inconsistent
Variable or sluggish rotation suggests either a drive parameter issue - speed reference, frequency output - or a mechanical problem creating drag. Debris or product that's fallen under the turntable is a common cause of increasing drag that's easy to miss.
Grinding or unusual noise during rotation
A grinding noise that's appeared gradually points to a bearing or drive component wearing. A sudden grinding usually means something is in contact with the underside of the turntable - stop the machine and check before running it again.
Manual mode works but auto doesn't
If the turntable rotates in manual but won't run in auto, the drive itself is fine. The issue is in the control sequence - a sensor input the PLC is waiting for, or a program condition that isn't being met before rotation is allowed to start.
Drive fault or alarm code on display
An alarm code on the inverter or control panel is the drive telling you what stopped it. Record the code before resetting. Common codes relate to overcurrent, overload, communication loss or brake fault. The code narrows the diagnosis significantly.
Typical causes
Drive motor or inverter fault
The inverter controls turntable speed and direction. A drive trip - overcurrent, overtemperature, communication fault - will stop rotation and log a code. Inverter faults need to be diagnosed from the code rather than reset and ignored, as the same fault will recur.
Mechanical obstruction under the turntable
Stretch film tails, product that's dropped from a load, or debris accumulation under the turntable can create enough drag to trip the drive on overload. The turntable itself may be physically fine - the problem is in what's sitting underneath it.
Brake not releasing
Most turntable drives use an electromagnetic brake that holds the table when the machine isn't running. If the brake doesn't release when power is applied - brake coil fault, wiring issue, or mechanical brake wear - the drive will trip on overload trying to turn against it.
Overload from excessive load weight or speed
If the load weight or turntable speed is at or beyond the drive's rated capacity, the inverter will trip on overload protection. This can also happen if a load shifts during wrapping and becomes unbalanced, putting intermittent overload on the drive.
What to check first
Don't reset and retry without recording what stopped it. The fault code is useful information - losing it by resetting means starting the diagnosis from scratch.
Check for and record any fault codes
Check the inverter display and the machine control panel for any alarm or fault codes. Write them down before resetting. If you've already reset without noting the code, run the machine again and let it fault - the code will return.
Check for obstructions under the turntable
With the machine isolated and safe to work on, look and feel under the edges of the turntable for film tails, debris or product. Clear anything you find. Film that has accumulated over time can bind the turntable mechanism without being immediately visible.
Try manual mode to isolate whether rotation is possible at all
If the machine has a manual or jog function, try rotating the turntable manually. If it runs in manual but not in auto, the drive is functional and the fault is in the control sequence or a sensor input. If it won't run in manual either, the drive or motor needs investigation.
Listen to the motor on start
When you attempt to start, listen to the motor. A motor that hums but doesn't turn suggests the brake isn't releasing or there's a mechanical lock. A motor that starts and then trips suggests overload. No sound at all from the motor points to a control or supply issue upstream of the drive.
If any of these apply, don't wait
- The drive is showing a fault code you can't identify or that keeps returning after reset
- The motor hums but the turntable doesn't move - brake or mechanical fault suspected
- Grinding noise has appeared during rotation
- The turntable runs in manual but won't run in auto and you can't identify the blocking sensor
Inverter faults that are reset repeatedly without identifying the root cause will often worsen. If the drive is tripping on overload, there is a reason - continuing to run it risks damaging the drive further.