How a sachet or vertical form-fill-seal process works
Unwind and control film
Maintain web tension and guide the printed laminate through coding and registration sensors.
Form the pack
Shape film around a forming set or bring webs together to create the intended sachet geometry.
Make the initial seals
Create longitudinal and/or transverse seals with controlled alignment, heat, pressure and dwell.
Dose the product
Deliver the programmed volume while protecting the sealing area from strings, splashes and pieces.
Close and cut
Form the final seal, cut or perforate the pack, and discharge it without damaging a warm seal.
Inspect and collate
Check relevant print/seal features and count or group sachets for secondary packing.
Treat the laminate as a machine component
The film supplier, product and machinery supplier should agree the intended structure and operating window. Roll width alone is not enough.
| Film input | Why it matters |
|---|---|
| Structure and sealant layer | Controls product compatibility and the available seal window. |
| Thickness and stiffness | Influence tracking, forming, wrinkles and cut behaviour. |
| Coefficient of friction | Affects web transport and contact with forming surfaces. |
| Print repeat and eye mark | Set registration logic and finished pack length. |
| Roll dimensions and winding | Determine unwind compatibility, changeover and handling. |
| Supplier tolerances | Need to be included in acceptance testing, not only a perfect trial roll. |
Confirm the machine direction, seal areas, eye mark, code zone, cut position and any clear or metallic regions before releasing a commercial print run.
Match the dosing system to flow, temperature and inclusion size
Low-dose sachets expose cut-off problems quickly because even a small tail can enter the seal area. The product may also cool faster in small hoses and nozzles.
Smooth low-viscosity sauce
Control splash, foaming and drain-down at short cycle times.
Viscous smooth paste
Use positive transfer and an effective anti-drip cut-off.
Seeded or fibrous product
Review clearances and whether fibres bridge the outlet or drag through the seal.
Products with pieces
Confirm the largest piece passes through the complete path and fits the formed pack opening.
Develop all seals across a practical operating window
| Seal | Control points | Common failure modes |
|---|---|---|
| Longitudinal seal | Overlap/fin geometry, tracking and continuous heat transfer. | Channel, wrinkle, contamination or misalignment. |
| Top/bottom seal | Jaw temperature, pressure, dwell, cooling and product timing. | Weak peel, burn-through, trapped product or fold. |
| Cut/perforation | Registration, blade condition and relationship to seal. | Cut through print, incomplete separation or damaged seal. |
| Spout/fitment seal | Component presentation and laminate compatibility. | Skew fitment, leak path or distorted film. |
Seal acceptance may use visual checks, controlled peel methods, leak tests or other agreed procedures appropriate to the pack. The website does not substitute for the packer's own food-safety validation.
Place variable information where it remains readable
Batch, date and traceability information may be printed on the web before forming. The stable code zone must avoid seals, folds, perforations and high-friction contact.
- Confirm print technology compatibility with the film surface and line speed.
- Set the eye-mark contrast and sensor position around the final artwork.
- Define code content, character height, orientation and inspection method.
- Allow for web stop/start behaviour and reject any unreadable transition packs.
- Keep the code legible after sealing, cutting, collation and outer packing.
Choose rollstock or pre-made pouches on total process needs
| Consideration | Form-fill-seal | Pre-made pouch |
|---|---|---|
| Pack creation | Machine forms each pack from rollstock. | Pack is converted and supplied ready made. |
| Format flexibility | Change forming set, film and settings. | Change magazine, grippers and pouch recipe. |
| Presentation | Efficient sachet/pillow formats; shape options depend on machine. | Broader premium pouch shapes and closures may be available. |
| Material development | High dependence on web, registration and sealing integration. | High dependence on pouch opening and handling consistency. |
| Best decision | Use samples, output, pack appearance and total cost—not format fashion. | Use samples, output, pack appearance and total cost—not format fashion. |