Inconsistent Package Length

Problem

Measured pack length drifts or varies package to package. The trend may correlate with speed, reel diameter, or a film batch change — the pattern is the fastest route to the cause.

Possible Causes

1. Film slip at the feeding rollers — worn, contaminated or insufficiently pressed.
2. Film feed encoder signal issues.
3. Tension behavior changed with a new film batch or reel size.
4. Mechanical backlash in the film feed path.
5. Registration corrections masking a primary length error.

What to Check

• STEP 1Measure the pattern.Log lengths of consecutive packs: slow drift points to tension or reel effects; random scatter points to slip or measurement.
• STEP 2Inspect feed rollers.Check for glazing, product residue, and pressure per the machine manual.
• STEP 3Verify encoder mounting and cabling.Confirm the film feed encoder is securely fixed and its cable undamaged.
• STEP 4Correlate with film changes.Check whether the variation began with a new film batch or reel size.
• STEP 5Rule out registration interaction.Observe raw length behavior to separate registration correction from primary feed error.

Corrective Actions

• Clean or recondition feed rollers and record the intervention.
• Qualify each new film batch with a measured sample run before production.
• Keep a length trend log per product — it shortens diagnosis dramatically on recurring issues.
• Secure or service the encoder mounting where movement or damage is found.