An in-mould label can be printed correctly and still fail at the next operation because the finished stack is counted incorrectly, reversed, mixed with another job or difficult to present to the moulding process. These are not details to settle after die-cutting. The converter needs an approved output specification before the reel reaches the finishing line. Start with the physical label, stack and pack that the receiving process can accept, then configure inspection, cutting, counting and collection around that result.
Start with the label and stack required by the receiving process
Obtain the approved label drawing, material identification, printed artwork reference and finished dimensions. Add the running direction, print-face orientation and the way the label must be presented in the stack. If the moulding or handling equipment uses a defined leading edge, datum or pick position, show it on a drawing rather than describing it only in words.
Define the number of labels per stack, permitted count tolerance, stack height limit where applicable, separator or interleave requirement and the inner and outer packing arrangement. State whether different designs, shapes, cavities or language versions may share a production order and how they must remain separated. A correct label in the wrong stack is still a release failure.
Keep a physical approved stack or a dimensioned packing standard where possible. Photographs are useful for orientation, but they do not replace the material code, label revision, count and packaging details. Agree who accepts the first stack and what evidence must accompany it before the full reel is converted.
Map every operation from printed reel to collected stack
Write the intended route in order: unwind, web guiding, printed-register control, inspection, die-cutting, waste removal, cutting or sheeting, counting, stacking and packing. Identify which stage creates the final label edge and which stage confirms the count. This prevents an option being added to the line without a defined production responsibility.
PRATI describes SATURN Omnia as a modular multiuse platform for self-adhesive labels, in-mould labels, flexible packaging, A4 sheets and wet-glue labels. Its current product information also refers to stacking different-shaped wet-glue and in-mould labels. That range is useful only when the offered configuration is checked against the exact web width, repeat, material, die-cut, inspection and output required for the job.
Do not treat roll-to-roll, roll-to-sheet and roll-to-stack as interchangeable outputs. Each requires its own release criteria and material flow. Confirm how rejected labels are removed, how the count is corrected after a stop, and how completed stacks are transferred without losing their identity or orientation.
Inspect the incoming reel before using finishing adjustments
Record the reel identity, material and batch, web width, print repeat, splice positions and the approved print reference. Check the first accessible repeats for register, damage and the correct design sequence. If the printed image or web position is outside the agreed condition, preserve the evidence instead of moving the die or guide to hide an upstream fault.
Use production material for the setup and acceptance trial. A substitute film or paper may feed, cut and stack differently from the job material even when the nominal dimensions are similar. Keep samples from the start, normal running condition, stop and restart, and the final accepted stack.
Separate print inspection from stack inspection. A camera or operator may confirm that the printed image is present and in register, while the release check still has to confirm the physical cut label, orientation, count and pack. Save both records against the same reel and job identity.
Prove the die-cut result before evaluating the stack
Inspect the complete perimeter of representative labels from across the web and around the repeat. Record incomplete cuts, tags, damaged corners, distortion or visible debris and match each fault to its position. Do not compensate for a local cutting fault by changing the complete stack process.
Keep the die, cylinder or cutting-tool identity with the job. Record the setup condition and any adjustment made after warm-up. If the design contains several shapes or closely spaced labels, confirm that every version releases and reaches the correct collection position. A stack that looks square can still contain a repeated cutting defect.
Check waste removal separately. Confirm that waste leaves the cutting area and does not enter the finished stack or remain attached to a label. Where a stop is needed to clear waste or correct a cut, identify the last accepted stack and repeat the count and orientation check after restart.
Validate counting, orientation and stack transfer through real events
Run enough material to include startup, stable production, a controlled stop, restart and an approved changeover. Verify the first and last label in selected stacks, the number of labels, print-face direction, leading-edge direction and separation between designs. Record the machine counter and the physical count used to approve the result.
Challenge the process with events that occur in production, including a splice, a rejected repeat and removal of an incomplete stack. The procedure must explain whether that stack is completed, recounted or quarantined. Do not return a partial stack to production without a controlled identity and count.
Confirm that the transfer from collection point to inner pack preserves the accepted condition. Mark the job, revision, design, quantity, line and production time on the container or traveller required by the plant. If several operators handle the stack, the handover should not depend on remembering which way it was facing.
Release the job with a retained stack standard
The release record should identify the printed reel, material batch, artwork revision, finishing route, tool, output configuration, accepted count, orientation, packing method and inspection result. Add photographs of the approved stack and labels from the top, middle and bottom where the plant procedure permits it. Retain a labelled sample appropriate to the customer and material requirements.
Review repeat problems by event and position. Mixed designs point to a different control failure from incomplete cuts, reversed stacks or count losses after a stop. Preserve the first failed stack before reworking it. The arrangement of labels inside it may show when identity or orientation was lost.
Royal Coat represents PRATI finishing technology across India, Bangladesh, Sri Lanka, Nigeria and Kenya. For an in-mould label roll-to-stack review, send the printed reel and material details, label drawing, web width, repeat, design sequence, die-cut requirement, inspection method, count and orientation standard, packing specification, normal run length, photographs and retained accepted and failed stacks.
Questions from production and purchasing teams
What to ask about in-mould label roll-to-stack finishing
What should an in-mould label stack specification contain?
Include the label and material revision, finished dimensions, print-face and leading-edge orientation, labels per stack, permitted count tolerance, separation between designs, stack or pack limits and the required inner and outer packing identification.
Does print inspection prove that an IML stack is acceptable?
No. Print inspection can confirm the image and selected defects, while the finished-product check must also verify the cut label, orientation, count, design separation, stack condition and packing.
Should a substitute material be used for the roll-to-stack trial?
Use the intended production construction wherever possible. A substitute may behave differently through guiding, cutting, waste removal and stacking, so its result should not be treated as final job acceptance without approval.
What happens to the count after a rejected label or machine stop?
The operating procedure should identify the affected stack, correct or restart the count by the validated method, and require a physical verification before that stack is released.
What information is useful when specifying an IML finishing configuration?
Provide the exact material, web width, repeat, artwork and design sequence, required inspection, die-cut and waste route, finished label dimensions, stack count and orientation, packing method, run length, changeover pattern and representative printed reels.