Opening and finished-output features
Sachet Tear Notches, Perforation and Cutting
A tear notch, perforation and final cut must be designed with the film, seal margins, print repeat and downstream process. Define the finished output early so tooling and registration are not treated as late artwork details.
Direct answer
What is the difference between a tear notch, perforation and cut?
A tear notch is a local opening feature intended to help the user start a tear. A perforation is a controlled line of weakness that can join sachets into a strip or define a tear path. A cut separates the finished pack from the web or from adjacent packs. The correct combination depends on how the customer opens, collates and handles the sachet.
| Feature | Primary purpose | Key specification inputs | Acceptance evidence |
|---|---|---|---|
| Tear notch | Start an easy-open tear at a defined edge | Profile, side, height, distance from seal/cut, film structure and tear direction | Position, clean formation, no seal damage and filled-pack opening test |
| Perforation | Create connected strips or a controlled separation line | Pitch, strength, orientation, lane map, strip length and downstream handling | Strip integrity during discharge plus repeatable manual or automated separation |
| Individual cut | Separate every sachet for counting or direct handling | Cut type, position tolerance, pack length, code and registration relationship | Clean edge, correct length, no cut into seals and reliable downstream transfer |
Specify the tear notch from the user opening task
State which side the customer will open, the intended tear direction and whether the notch must be visible on a printed face. V- and U-shaped notches are common descriptions, but the selected profile, blade and position must suit the film and pack design. No single notch shape is automatically best for every laminate.
Keep the notch clear of the product cavity and critical seal corners unless the complete design has been validated. A notch that looks correct on an empty web may behave differently on a filled, tensioned sachet.
Use perforation when connected sachet strips are part of the process
Connected strips can simplify bundling, display or secondary packing, but the perforation must survive discharge and handling while still separating as intended. Define the number of sachets per strip, perforation direction, lane mapping, allowable broken strips and how the downstream process will count or collate them.
For multi-lane machinery, confirm whether perforations run between packs, between lanes or both. The drawing should show every pitch and the relationship to cross-seals.
Match individual cutting to the next operation
Individual sachets may be easier to count, inspect or feed into a cartoner, but they can be difficult to control if they are light, flexible or discharged at different orientations. Define edge quality, cut position, finished length and the receiving conveyor, chute or collection method.
If the next process uses vision, counting or robotic handling, provide the presentation requirement rather than specifying only that sachets should be “cut separately”.
Coordinate the feature with registration, coding and seals
The eye mark tells a registered-film machine where the repeat sits, but the finished pack still needs a controlled relationship between artwork, code, notch, perforation, seals and cut. Put those elements on one dimensioned drawing and include tolerances.
- Keep the variable code inside its approved print window.
- Keep the cut clear of the seal band and product cavity.
- Check that a splice does not create an unacceptable feature or registration fault.
- Define the reject response when the photocell cannot confirm the print repeat.
Test the actual film and tooling together
Film structure, gauge, orientation and tear behaviour influence notch and perforation performance. Use production-intent film, not a substitute with similar thickness. Check the feature after filling, sealing, cooling and normal downstream handling.
Cutting and notching components are wear parts. The maintenance plan should define safe inspection, replacement criteria, approved parts and checks after intervention. Operators should follow the machine manual and site isolation procedure.
Acceptance checklist
- Approve a dimensioned pack drawing containing every feature and tolerance.
- Run representative film and product across every required format.
- Check feature position at start-up, steady operation and after a planned stop or splice.
- Test opening and separation on filled packs, not only empty film.
- Check downstream transport, counting and collation.
- Record defects, interventions, samples and the accepted-output case.
Information to send with the enquiry
| Pack drawing | Finished dimensions, seal layout, cavity, notch, perforation, cut and tolerances |
|---|---|
| Film | Structure, gauge, orientation, print repeat, eye mark and production-intent reels |
| Output format | Singles, strip quantity, lane order, count and downstream presentation |
| Quality | Opening method, separation test, edge criteria, registration and reject rules |
Buyer questions
Questions about opening and cutting features
Should sachets be supplied individually or in strips?
Choose from the consumer, counting, cartoning and handling requirement. Singles and strips create different cutting, perforation and downstream-control needs.
Can a tear notch be added to any sachet film?
Not automatically. Film structure, orientation, seal margins, tooling and the required opening behaviour must be checked with production-intent material and filled samples.
Does the photocell control the cut position?
On registered printed film, the photocell provides a reference for the print repeat. The machine recipe and mechanical setup then control how that reference relates to the seal and cut.
Why do perforated strips break before secondary packing?
Possible causes include excessive weakness, handling shock, unsuitable film behaviour, poor feature position or uncontrolled discharge. The strip and downstream route must be trialled together.
What should be checked after changing a cutter or notch tool?
Follow the machine manual and isolation procedure, then verify tool security, position, edge quality, feature alignment, guarding and sample-pack acceptance before releasing production.
Define the finished output
Send the pack drawing, film and downstream requirement
Lancing can review the notch, perforation and cutting requirement with the seal layout, print registration and handling process before machinery is specified.