Tray sealing is one of the most common packaging formats in food manufacturing and retail — and increasingly, it’s used well beyond food, in medical, industrial, and consumer goods applications too. Walk down any supermarket chilled aisle and you’ll see it: meat, fish, ready meals, fresh produce, and bakery items sitting in a rigid or semi-rigid tray with a film lid sealed tightly around the rim. Behind every one of those packs is a tray sealing machine.
For manufacturers evaluating packaging equipment for the first time — or looking to upgrade an existing line — understanding the different types of tray sealers, and what they’re each best suited for, is essential to making the right investment. This guide breaks down how tray sealing works, the main machine types, and how to match a system to your production needs.
How Does Tray Sealing Work?
At its core, a tray sealing machine takes a pre-formed tray (already filled with product), places a film lid over the top, and applies heat and pressure to bond the film to the tray’s rim — creating an airtight or protective seal. Many machines also cut the film to size and, where required, remove air from the pack or replace it with a protective gas before sealing.
The process typically involves:
- Tray infeed — Filled trays enter the machine, either manually loaded or fed automatically from an upstream filling process.
- Film feeding — A roll of lidding film is drawn across the top of the tray.
- Sealing — A heated sealing tool presses the film onto the tray rim, bonding the two together.
- Atmosphere modification (where applicable) — Air inside the pack may be evacuated and replaced with a gas mix to extend shelf life.
- Cutting and discharge — Excess film is trimmed away and the sealed tray moves on to labelling, cartoning, or dispatch.
Types of Tray Sealing Machines
Traditional (Ambient Air) Tray Sealers
The simplest form of tray sealing, these machines seal a film lid onto the tray without modifying the internal atmosphere. They’re straightforward, fast, and cost-effective — well suited to products with a shorter required shelf life or those that don’t benefit significantly from gas flushing.
Best for: bakery items, fresh produce with a short shelf window, ready meals sold and consumed quickly, and any product where cost-efficiency matters more than extended shelf life.
Modified Atmosphere Packaging (MAP) Tray Sealers
MAP tray sealers remove the ambient air inside the tray before sealing and replace it with a specific gas mixture — commonly combinations of carbon dioxide, nitrogen, and oxygen — tailored to the product being packed. This significantly slows spoilage, preserves colour and texture, and extends shelf life, which is critical for retail distribution.
Best for: raw and cooked meat, fish, poultry, dairy, and other perishable goods that need extended shelf life for supply chain and retail requirements.
Vacuum Skin Packaging (VSP) Tray Sealers
A step beyond standard MAP, vacuum skin packaging draws a flexible film tightly over the product, almost like a second skin, removing virtually all air and moulding closely to the product’s shape. This offers excellent product presentation, leak resistance, and shelf life extension.
Best for: premium meat and fish products, retail displays where visual presentation matters, and products prone to leakage in standard trays.
Rotary vs. Linear Tray Sealers
Beyond the sealing method, tray sealers also differ in their mechanical format:
- Rotary tray sealers use a continuously rotating sealing mechanism, allowing very high throughput — well suited to high-volume operations running large numbers of trays per minute.
- Linear (intermittent motion) tray sealers seal trays in batches as they stop momentarily under the sealing head. These are typically more flexible for handling multiple tray sizes and are well suited to mid-volume operations or facilities running varied product lines.
Choosing the Right Tray Sealer for Your Line
1. Consider Your Required Shelf Life
If your product needs to travel further, sit longer in distribution, or hold retail shelf presence for several days or weeks, MAP or VSP sealing is likely necessary. If your supply chain is short and turnover is fast, a traditional sealer may be perfectly adequate — and considerably more cost-effective to run.
2. Match Machine Speed to Your Output Targets
Rotary sealers deliver high throughput but are generally less flexible with tray size changes. Linear sealers offer more flexibility for varied production but at a lower top-end speed. Be realistic about your actual required output — over-specifying speed adds unnecessary cost, while under-specifying creates a bottleneck.
3. Factor in Tray and Film Compatibility
Not all sealers work with every tray material or film type. If you’re using recyclable or mono-material packaging (increasingly a requirement for sustainability commitments and regulatory compliance), confirm your chosen machine is compatible with those materials and can achieve a reliable seal.
4. Plan for Product Variety
If your facility runs multiple SKUs with different tray sizes, look for machines with fast, tool-less changeovers. A sealer that requires lengthy manual adjustment between formats will slow your whole line down.
5. Think About Integration
Your tray sealer doesn’t operate in isolation — it needs to work smoothly with upstream filling or portioning equipment and downstream labelling, checkweighing, metal detection, and cartoning systems. A well-integrated line minimises manual handling and reduces the risk of bottlenecks or quality issues.
6. Don’t Overlook Hygiene and Cleaning Requirements
For food production environments, machines need to be designed for fast, thorough washdown and cleaning between shifts or product changeovers, with hygienic construction that meets food safety standards.
Common Signs You Need to Upgrade Your Tray Sealing Equipment
- Frequent seal failures or leaking packs reaching customers or retailers
- Manual or semi-automatic sealing creating a production bottleneck
- Inability to meet shelf-life requirements for new retail contracts
- Increasing downtime or maintenance costs on ageing equipment
- Difficulty sourcing recyclable or sustainable packaging materials compatible with your current machine
Frequently Asked Questions
What’s the difference between MAP and vacuum skin packaging?
MAP replaces the air inside a tray with a protective gas mixture while keeping the tray’s original shape, whereas vacuum skin packaging draws film tightly over the product itself, moulding to its shape and removing virtually all air for a tighter, leak-resistant pack.
Are tray sealing machines compatible with recyclable packaging?
Many modern tray sealers can run recyclable or mono-material trays and films, but compatibility depends on the specific machine and sealing technology. It’s worth confirming this with your supplier early if sustainable packaging is a business priority.
How do I know if I need a rotary or a linear tray sealer?
Rotary sealers suit high-volume, relatively consistent production runs, while linear sealers offer more flexibility for facilities running multiple tray sizes or lower to mid-range volumes. Your actual throughput and product variety should drive this decision.
Can tray sealers integrate with existing filling equipment?
Yes, and they generally should. A tray sealer is most effective when it’s integrated smoothly with upstream filling or portioning and downstream labelling and cartoning equipment, minimising manual handling across the line.
Getting Expert Guidance Before You Invest
Tray sealing equipment represents a significant investment, and the right choice depends on your product, shelf-life requirements, throughput targets, and existing production line — not just the headline features on a spec sheet.
At LVP Automation, we help Irish manufacturers assess their tray sealing requirements from the ground up, recommending traditional, MAP, or VSP systems — and rotary or linear formats — based on your actual product, packaging materials, and production goals. We also ensure your tray sealer integrates cleanly with the rest of your line, from filling through to final dispatch.
Get in touch with LVP Automation to discuss the right tray sealing solution for your production line.
