Why Is the Seal Weak?

Problem

Seals tear open easily by hand or in transport, or seal quality varies through the run — some packages hold, others open at the same seam position. The fault often appears after a film batch change or a speed increase.

Possible Causes

1. Sealing temperature is below the film's sealing range, or the controller is oscillating.
2. Jaw pressure is uneven across the seal face, or sealing jaws are worn.
3. Sealing surfaces are contaminated with product residue or film debris.
4. Seal dwell time is too short for the current production speed.
5. The film structure or supplier has changed without re-qualifying parameters.

What to Check

• STEP 1Verify the temperature setpoint.Compare against the film supplier's data sheet and confirm the actual temperature is stable at the jaw.
• STEP 2Inspect the sealing jaw faces.Look for residue, scoring and uneven contact; compare the jaw impression left on a piece of paper.
• STEP 3Run a short batch at reduced speed.If seals improve at lower speed, dwell time at production speed is the likely limit.
• STEP 4Confirm the film batch and structure.Check that the film on the machine matches the recipe's qualified specification.
• STEP 5Re-qualify after every change.Verify seals on consecutive sample packages before resuming production.

Corrective Actions

• Adjust temperature within the film supplier's recommended range in small steps, waiting for stabilization between changes.
• Clean or recondition worn jaw faces and restore even pressure.
• When speed must be maintained, work with Path Pack support to re-match dwell and pressure for the application.
• Store the qualified parameter set in the product's recipe and re-qualify after any film change.