1. The Client Brief & Challenge
A fresh-cut vegetable supplier had won a new contract to supply shredded iceberg lettuce to fast food outlets. The customer already packed lettuce and needed an additional line at one production site, designed to produce 30 bags per minute at 2.5 kg per bag within a tight delivery window and budget.
- Light, damp product: Washed lettuce has low bulk density and can stick during conveying and weighing. The line needed sufficient bucket volume and product distribution suited to shredded leaves.
- Heat-sensitive film: The customer specified a mainly polyethylene-based film with a narrow sealing window. Nitrogen flushing and seal control were needed to support the intended shelf life.
- Washdown throughout: The conveyors, weighing system, platform and bagger had to support washdown cleaning and access for dismantling and reassembly.
- Room, budget and deadline: The layout had to suit the production room, with delivery requested in under four months and installation limited to a weekend.
2. The Process Plant Network Solution
PPN supplied an all-new line using IOPAK, its in-house machinery brand. Custom conveyors and a washdown platform were combined with a multihead weigher and bagger modified for the application. The bulk hopper and incline conveyor feed the weigher; measured portions drop into a continuous-motion vertical form-fill-seal bagger before the finished bags leave on the outfeed conveyor.
The 14-head weigher uses 7.5 L dimple-plated buckets and a rotating cone to distribute the light, damp lettuce and limit sticking. A sturdy platform helps limit vibration at the weigher and includes a wash wall for cleaning its components. The bagger combines nitrogen flushing with sealing controls suited to the customer’s heat-sensitive film, while a date coder prints best-before information.
The line was configured for 2.5 kg bags measuring 320 mm wide by 510 mm long, with the layout customised to suit the customer’s production room.
System Equipment Composition
New Equipment
- Custom washdown bulk hopper feed conveyor.
- Custom incline elevating conveyor to feed the multihead weigher.
- 14-head multihead weigher with 7.5 L dimple-plated weigh buckets and a rotating distribution cone.
- Custom heavy-duty washdown platform with a wash wall.
- Continuous-motion, servo-driven vertical form-fill-seal bagger with nitrogen gas flushing.
- Outfeed conveyor for finished bags.
- Date coder for best-before information on the bag.
Proof of Concept & Workshop FAT Testing
The complete line was assembled at PPN and factory acceptance tested with the customer using several megabins of shredded lettuce. Testing brought the product, weighing system and specified film together before the line was dismantled and dispatched for installation.
