TL;DR

Worn drive chains cause pitch error and label indexing drift. Measure chain elongation and sprocket wear, and replace when the elongation exceeds the service limit.

What you might see

indexing inaccurate at high speed
chain slap or rattle noise
label pitch drifting over a production run
chain link wear measurement above spec

Likely causes

Tap to mark as ruled out

Chain elongation from extended operation reducing sprocket engagement accuracy
Sprocket tooth wear causing backlash and indexing error
Lubrication failure accelerating chain pin and bushing wear
Chain contamination from cleaning chemicals or product attacking the lubricant

Required tools

Chain elongation measuring tool or steel rule
LOTO kit
Chain lubricant (food-grade H1 rated)
Replacement chain and sprocket set

Safety first

Chain and sprocket drives have severe entanglement hazards. Lock out the drive completely before removing any covers.
Use food-grade H1 rated chain lubricant. Do not use mineral oil lubricants on chain drives exposed to food contact surfaces.

Procedure

7 steps · ~30 min

1
Stop the labeler and lock out. Remove the drive cover.[1]
2
Measure the chain elongation by pulling a known number of links tight and comparing the length to the new-chain specification. Elongation above 3 percent indicates replacement.[1]
3
Inspect the sprocket teeth for hooked or undercut profiles. Worn sprockets cause chain jump.
4
Check the chain lubrication. A dry chain or one contaminated with cleaning chemical will elongate faster.
5
Check the drive belt (if fitted) for cracking, fraying, or tension loss.
6
Replace chains and sprockets as a matched set. Installing a new chain on worn sprockets accelerates the new chain wear.
7
Re-lubricate the new chain per the specified interval and lubricant grade.

Sources

Krones Krones Contiroll / Solomatic Labeler / Cartoner general technical documentation, Krones
Krones Contiroll / Solomatic labeler general drive chain and belt maintenance procedures (general)

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