Tray sealing is the most widespread solution for packaging fresh meats, ready meals, cheeses and fresh produce for retail. It combines vacuum or MAP with a rigid, visually effective pack on the shelf.
How a tray sealer works
The pre-formed tray is inserted into the machine cavity. The upper plate lowers the cover film onto the tray, applies vacuum (and/or MAP gas) and seals the film with a heated plate at 140-200°C. After cooling, the pack is ready and the film is sealed across the entire rim.
- Tray in PET, PP, CPET or aluminium loaded manually or automatically
- Cover film: PA/PE, OPP/PE, PET/PE depending on required barrier
- Vacuum up to 99.5% or MAP gas flushing
- Sealing at 140–200°C for 1.5–4 seconds
- Easy-peel or permanent sealing available
Manual, semi-automatic and automatic tray sealers
Manual tray sealers require an operator for each cycle; investment costs are low (from €8,000) and suit production up to 400-600 trays/hour. Semi-automatics automate film advance but keep manual loading: up to 1,200 trays/hour. Automatic in-line tray sealers integrate conveyors, dosers and robots: 2,000-8,000 trays/hour.
- Manual: 400-600 trays/h — ideal for labs and small production
- Semi-automatic: 800-1,200 trays/h — cost/productivity balance
- Automatic in-line: 2,000-8,000 trays/h — for retail and large industry
Parameters that determine seal quality
An imperfect seal compromises shelf life and may cause retail rejections. Critical parameters are film-tray compatibility, temperature, contact time and plate pressure. Seal integrity is verified by immersion tests or gas chromatography for MAP packs.
- Film/tray compatibility: always test before production launch
- Temperature: ±5°C variation compromises the seal
- Plate pressure: 3-6 bar depending on material
- Rim contamination: main cause of micro-leaks
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