Start with a dimensioned finished-sachet drawing
Show finished width and length, longitudinal and transverse seal bands, tear notch, corner or cut form, perforation, coding area and the clear internal space available for product. Identify whether dimensions are nominal and state tolerances where they are controlled.
Do not assume the outside pack area equals usable fill volume. Seals, headspace, nozzle clearance, product settling and the distance needed to keep product out of the jaws reduce the internal space. Trial the intended dose in a representative pack geometry.
Relate dose to density, shape and headspace
A mass value does not define volume. Powder bulk density can change with aeration and settling; granules occupy space according to particle size and packing; liquids and pastes need headspace for clean cut-off and sealing. Include the range that occurs in production.
For a family of doses, identify the most demanding combination rather than only the smallest and largest figures. A low-density powder at an intermediate weight can need more pack volume than a heavier dense product.
Define the film web as a controlled machine input
Provide laminate structure, thickness, web width, reel core, maximum reel diameter or mass where relevant, winding direction and splice method. For printed film, add repeat length, eye-mark drawing, lane layout, artwork revision and print tolerance from the converter.
Film width is not simply finished sachet width multiplied by lane count. Longitudinal seal overlap, lane pitch, slit/cut allowance, edge trim and the machine’s forming arrangement must be calculated by the supplier from the approved pack and web drawing.
Select a seal pattern that matches the forming route and pack need
Back-seal packs use a longitudinal fin or lap seal plus top and bottom transverse seals. Three-side and four-side formats use different web handling and seal layouts. Stick packs are typically narrow and rely on a controlled longitudinal back seal.
State the required finished appearance and opening method, but allow the machinery and film review to confirm practical seal widths. Seal strength and integrity depend on compatible materials, clean sealing surfaces and a validated temperature/pressure/dwell window.
Create a lane map for multi-lane webs
Number every lane and show lane pitch, finished width, longitudinal seals, slit positions, transverse cut or perforation, artwork, registration marks and code areas. Confirm whether finished packs leave individually or in linked groups.
Lane maps should be used by the film converter, machine supplier, coder and quality team. During acceptance, retained samples and dose/seal/code records should identify the lane.
Protect artwork from seals, cuts and normal web variation
Establish quiet zones around seals, notches, cuts, perforations and variable-code areas. Keep critical text and regulatory content within the converter’s and machine’s controlled print/cut window. Review the final artwork against the approved technical drawing before film is ordered.
When artwork changes, control the revision and confirm that the print repeat and eye mark have not changed unintentionally. A visual design approval alone is not a machine-web approval.
Match material performance to product and process
The film supplier should confirm that the structure is suitable for the intended product, filling temperature, sealing process, storage, distribution and shelf-life requirement. Food-contact applications require suitable materials and documented compliance for the intended use.
Machinery trials establish runnability and seal-process conditions; they do not replace product shelf-life, migration, compatibility or regulatory assessments. Retain the film specification and reel identification with trial evidence.
Sachet and film specification worksheet
| Finished pack | Width, length, tolerances, seal bands, tear notch, corner/cut, perforation, linked or individual discharge. |
|---|---|
| Product and dose | Nominal and range, mass/volume/count basis, density or viscosity range, particles, settling and required headspace. |
| Film structure | Layer description, total thickness, sealant layer, declared suitability, friction/handling information and supplier data sheet. |
| Reel | Web width, core, outer diameter or mass, winding direction, print side, splice and reel identification. |
| Artwork revision, repeat length, eye-mark dimensions/contrast, lane map, tolerances and approved code area. | |
| Machine relationship | Forming route, longitudinal seal type, lane pitch, slit/cut/perforation positions, sensor and coder arrangement. |
| Quality method | Dimension, registration, code, visual seal and integrity tests, sample frequency and acceptance rules. |
| Trial evidence | Production-intent reel, product batch/condition, settings, retained packs, lane identity and approved deviations. |
For food applications, review the intended material and use with the film supplier and the current Food Standards Agency food-contact-material guidance. Machinery trials do not replace regulatory, migration, shelf-life or product-compatibility assessment.