Sachets and pouches are commonly rejected by a controlled air blast, drop flap or retracting belt, but the best method depends on pack weight, fill movement, seal profile, presentation and line speed. Stable belt support and accurate tracking are essential because flexible packs can slip, curl, overlap or catch on guides.
Handle the pack before rejecting it
Why are flexible packs harder to reject?
A rigid carton presents a repeatable face; a pouch can change shape as its contents move. Leading seals may lift, gussets can catch a guide and light sachets can be affected by airflow or static. These behaviours influence both product detection and the path taken after the reject device operates.
The conveyor should support the full pack, minimise uncontrolled transfers and maintain enough separation for the inspection and reject windows. Side guides, hold-down arrangements or belt choice may be needed, but must not trap a failed pack.
Air blast, flap or retracting belt?
Air blast can suit light, well-presented packs where a short jet provides clean separation. Nozzle direction, air volume and the receiving chute are proven by trial. A drop flap or retracting belt creates a downward path and can be more controlled for packs that fold around a pusher or respond inconsistently to air.
A mechanical pusher is possible for some robust filled pouches, but the contact face must avoid riding over, underneath or into the pack. The decision is based on the complete product range, not only the nominal pack size.
Inspection and product tracking
Sachets may be rejected after checkweighing, metal detection, X-ray, vision inspection, code verification or seal checks. The failed decision must remain associated with the correct pack even if the pouch slips relative to the belt. Sensor placement and, where appropriate, encoder tracking are configured around that risk.
Hygiene and reject containment
Food and pharmaceutical applications can use stainless-steel, cleanable construction with removable reject containers. Bin-present, full-bin and independent reject confirmation sensors can support a defined fail-safe response. The required materials and cleaning approach are agreed from the site environment.
Key project considerations
- Pillow packs and flat sachets
- Stand-up and gusseted pouches
- Flexible food and beverage packs
- Pharmaceutical sachets
- Checkweigher and inspection integration
- Cleanable stainless-steel construction