1. Loading the tray
The product is placed in a preformed tray, which goes into the sealing mould: by hand on manual and semi-automatic machines, or by conveyor on automatic ones.
Tray sealing: what it is and how it works
Tray sealing closes a pack with heat and pressure: a lidding film is welded to the rim of a preformed tray. It is the basis of tray packaging for meat, fish, ready meals, cheese and cut fruit.
The tray sealing process, step by step
2. Atmosphere (optional)
If the product needs it, the chamber closes and a vacuum is drawn, gas is injected (MAP) or skin film is applied. If not, the tray is sealed in air.
3. Sealing and cutting
A heated plate presses the film onto the tray rim for a set time and at a set temperature. The film is then cut to the outline and the waste is rewound.
Trays and lidding film
Tray and film are chosen together: the film has to seal onto the tray material. Plastic, aluminium and fibre trays are used, plain or compartmented, with clear, peelable or high-barrier films depending on the product and the planned storage.
Three settings govern seal quality: temperature, time and pressure. A rim free of product, fat or liquid matters as much as the machine settings. Our manual tray sealers adjust temperature from 0 to 240 °C.
A new tray format means a new mould, so it pays to decide early which trays you will use.
Types of tray sealer
| Type | How it works | Reference output | Models |
|---|---|---|---|
| Manual | The operator places the tray and lowers the head | 450 trays/hour | NEX-175, 175D, 225, 225D ↗ |
| Tabletop | Manual loading with gas flush, MAP or skin | 2–6 cycles/min | NEX-271, 272, 273 ↗ |
| Semi-automatic | The operator loads; the machine evacuates, flushes, seals and cuts | Seal only: 7–8 cycles/min | NEX-450M/2 ↗, NEX-550M ↗ |
| Rotary | Alternating loading and sealing on a rotating platform | Seal only: 7–8 cycles/min | NEX-370R ↗, NEX-450R ↗ |
| Automatic | Trays fed by conveyor, in line | Seal only: 8–10 cycles/min (NEX-450A) | NEX-450A ↗ and others |
One cycle can seal several trays depending on the mould. Figures are indicative and are confirmed in the quotation.
Tray sealing FAQs
What is tray sealing?
Closing a pack with heat and pressure, usually a film sealed onto the rim of a preformed tray.
What is the difference between tray sealing and thermoforming?
In tray sealing the tray arrives preformed and the machine only closes it. In thermoforming the machine makes the pack in line from a roll of film. We explain it in the thermoformer vs tray sealer guide.
What is lidding film?
The top film sealed onto the tray. It can be clear, peelable (easy-open) or high-barrier, and must be compatible with the tray material.
Can trays be sealed with modified atmosphere?
Yes. Tray sealers configured for MAP draw a vacuum and inject gas before sealing; some also run vacuum skin.
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