TL;DR

A glue blockage stops labeling. Check the glue tank level and temperature first, then trace the supply path from tank to drum for solidified glue.

What you might see

glue not reaching the glue drum or application roller
label not sticking to container
glue pump running but no flow indication
cold glue tank temperature above setpoint

Likely causes

Tap to mark as ruled out

Solidified glue in a supply line or nozzle from a temperature drop
Glue tank heater failure allowing the glue to solidify
Glue pump filter blocked with paper or glue skin
Glue type changed to an incompatible viscosity grade

Required tools

IR thermometer
Heat-resistant gloves
Approved glue line cleaning solvent
LOTO kit
Cleaning brushes

Safety first

Hot melt glue operates above 150 degrees C. Splashed or dripped glue causes severe burns. Wear heat-resistant gloves and face protection at all times near the glue system.
Lock out the glue pump and heat system before opening any supply line connection.

Procedure

7 steps · ~30 min

1
Check the glue tank level. Low level can allow air into the pump causing a vapor lock.
2
Verify the glue tank heater is at the correct setpoint and the actual temperature is within 5 degrees C of setpoint.
Warning: Hot melt glue is at high temperature. Wear heat-resistant gloves and face protection when working near the glue tank or supply lines.
3
Check the glue supply line from the tank to the pump for cold spots using an IR thermometer. A cold section indicates a blockage or a failed heat trace.[1]
4
Lock out the glue system and allow it to cool if a line disassembly is needed. Do not disconnect hot melt lines while under pressure or temperature.[1]
5
Remove and clean the glue pump inlet filter. Rinse with the approved solvent for the glue type.
6
If a line is blocked with solidified glue, apply external heat (heat gun) gently to the blocked section while maintaining glue tank temperature.
7
After clearing the blockage, prime the pump and confirm glue flow at the drum before restarting production.

Sources

Krones Krones Contiroll / Solomatic Labeler / Cartoner general technical documentation, Krones
Krones Contiroll / Solomatic labeler general glue system maintenance and blockage procedures (general)

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