TL;DR
Layer pattern misfeeds are almost always caused by an infeed conveyor speed mismatch or a case stop photo-eye not detecting cases reliably. Check sensor alignment and verify conveyor speeds match the pattern recipe.
What you might see
- cases arrive at the layer forming station out of sequence
- layer pattern fault alarm on the HMI
- jams at the tier sheet or case positioning conveyor
- pallets with incorrect layer patterns
Likely causes
Infeed conveyor speed out of sync with the layer former cycle time causing case gaps or overlaps
Reflective photo-eye sensor dirty or misaligned, missing cases or double-detecting
Case stop solenoid valve sticking, releasing cases late or not releasing at all
Product recipe parameters in the HMI not matching the actual case dimensions
Required tools
- HMI access for recipe and I/O diagnostics
- Lint-free cleaning cloth for photo-eyes
- Compressed air and screwdriver for solenoid valve inspection
Safety first
- Palletizer machines have large, heavy moving heads and can deliver crushing force. Always use the machine's safety-rated access interlock before entering any guarded zone.
- Confirm the palletizer is in a safe-access state and cannot cycle before reaching into the case metering or layer-forming area.
Procedure
- 1
Review the active recipe on the HMI and confirm the case length, width, and height parameters match the actual cases being run.[1]
- 2
Clean the infeed photo-eyes with a lint-free cloth. Confirm the sensor indicator LED is solid (not flickering) as cases pass by.
Warning: Before entering any guarded area of the palletizer to check sensors or mechanical stops, use the area gate interlock or the safety-rated access key switch to put the machine into a safe access mode. The palletizer head has large moving masses. - 3
Run the machine at reduced speed (if your HMI supports a jog mode) and observe case metering. Count cases versus expected count per layer.
- 4
Check the case stop cylinder actuation timing on the HMI I/O diagnostic screen. Compare the actual dwell time to the recipe setpoint.
- 5
Inspect the case stop solenoid valve for air leaks or internal contamination. Replace the solenoid if it is slow to respond in either direction.
- 6
If misfeeds persist only with specific SKUs, compare infeed conveyor speed and case metering timing for that product recipe against a product that runs correctly.
Sources
Columbia / Okura Columbia FL / GP / HL Palletizer (Robotic / Conventional) general technical documentation, Columbia / Okura
Robotic and conventional palletizer programming and troubleshooting, case metering systems, general material handling references (general)
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