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Tray Sealing 101

Organizations in the food and beverage industry understand how vital packaging can be in keeping food fresh, ensuring it is easily transportable, and attracting customers. However, with so many different food packaging solutions available on the market, it can be easy to get lost in the jargon and variety of options.

Don’t stress. Your friends at Crawford Packaging are here to make it simple for you with this complete guide to tray sealing.

What Are Tray Sealers?

Also referred to as tray lidding machines, heat sealers, or top sealers; tray sealers are machines that apply plastic film lids to trays of varying materials, sizes, and depths. It is because of this versatility that top seal is the optimal packaging solution for a variety of applications, including industrial fasteners, fresh produce, meat, frozen meals, and ready-made meals.

various items in plastic trays on blue top seal machine outfeed conveyor

How Do Tray Sealers Work?

Product-filled trays enter the in-feed conveyor where they get indexed and spaced. These are then picked up by a transfer beam to be transferred within the tooling. The seal plate then picks up the product-filled trays and lifts them against the film. The film and trays are then compressed against the heated upper tooling to activate the sealing properties against the tray, while simultaneously cutting the film. Finally, after seal dwell time has elapsed, the seal station lowers the trays back down and the transfer on the next cycle ejects to the out-feed of the machine.


Types of Tray Sealing Machines

There are two main types of tray seal machines:

Packaging Automation PA182 – a semi-automatic tray sealing machine.

1. Semi-Automatic Tray Seal Machines

Semi-automatic tray sealers are most suitable for small and medium-sized operations.

Packaging Automation’s PA182 is a great example of a semi-automatic machine. The PA182 utilizes a rotating tray sealing station that is pushed manually by the operator. Just because it’s semi-automatic, doesn’t mean it’s not fast; the PA182 can seal up to 40 packs per minute.

Packaging Automation’s Revolution is a fully automatic tray sealing machine.

2. Automatic Tray Sealing Machine

Fully automatic tray sealers are most suitable for medium and large-scale operations. What makes them fully automatic are the conveyors that push the trays through the machine, lessoning the need for manual intervention.

Packaging Automation also offers several automatic machines, namely the Revolution. This tray sealing machine can seal up to 200 packs per minute, making it the fastest tray sealer on the market today.


Types of Tray Seal Films

  • Peelable – Film that can be removed once with minimal effort

  • Resealable – Film that can be opened and resealed by the consumer multiple times

  • MAP (Modified Atmosphere Packaging) – Film that has micro-perforations to control oxygen flow in and out of the package. This helps to extend the shelf life of perishable items.

peelable top seal film with green and red graphic print
peel and reseal technology top seal film with red graphic print
yellow and orange cherry tomatoes in top seal packaging tray

Tray Sealing Terminology

  • Tray: A solid, one-piece bottom that can be made from plastic, fibre, or metal.
  • Punnets: A small, light basket or other container often used for fruit and vegetables.
  • Tooling: Tooling is the physical component in the machine that is made to fit the product’s specifications. In top seal machines, there is tooling that contains the tray to seal the film, and as such, is made to match the profile of the tray to ensure proper seal positioning. Knife blades are also embedded in the upper tooling to create the cut profile to the desired tray.
  • Impressions: Count of each individual container placement (punnet or tray) within the tool.
  • Perforations (Micro and Macro): In this case, perforations are small holes that are cut onto plastic film.
  • Hermetic Seal: A hermetic seal refers to any type of sealing that makes a given object airtight.
  • Dwell Time: Refers to the amount of time it takes to activate time, heat, and pressure.

empty white trays with printed top seal film exiting outfeed conveyor of top seal machine

Benefits of Tray Sealing

  1. Reduce Plastic Material: Top seal packaging uses up to 25% less packaging material than traditional clamshell packaging.

  2. Extended Shelf Life: Top seal film helps protect products temperature changes that can cause food spoilage. This in turn reduces food waste as well as consumption.

  3. Improved Shelf Impact: Studies have shown that 50% of consumer purchase decisions are based on packaging. Therefore, the ability to customize trays and tray film provides an opportunity to increase branding and promote brand loyalty.

  4. Improved Product Safety: Tray sealing helps improve food safety by providing a strong airtight seal that minimizes the risk of contamination, as well as dirt and moisture from entering the container. Tamper-evident film provide consumers with clear evidence that a seal has been broken.

  5. Increased Flexibility: Many tray sealing machines can fit multiple tray sizes as well as the capability to can be integrated with other components in the production line.

  6. Reduced Downtime: The tooling can be changed in just 2 minutes by using interchangeable parts and a programmable interface. Remote diagnostics via the internet allow the Crawford Service Team to quickly diagnose and troubleshoot issues.

  7. Production Insight: Live web-based view of machine and its current operating state, live production statistics, historic details of stoppages, and changes to machine parameters.


How to Choose the Right Tray Sealer?

The choice of packaging machinery requires careful consideration of technical specifications, labour requirements, worker safety, maintenance, and flexibility. If you’re struggling to find the right machine, Crawford Packaging’s Packaging Specialists can conduct a packaging audit of your facility to determine the best machine and materials for your needs.

At Crawford Packaging, we take the complex problem of food packaging and simplify it by leveraging the expertise of our Packaging Specialists. Crawford is proud to offer a full complement of packaging consumables, both direct and indirect. No matter your product’s requirements, we’ll tailor a solution that will revolutionize the way you pack – guaranteed. Contact us today.

Tray Seal Case Studies

Learn how Crawford’s Tray Sealing solutions have helped other clients improve efficiencies and save on costs.


Crawford Packaging is a full-service packaging company located in London, Brampton and Waterloo, Ontario. From packaging to packaging equipment, installation and upgrades, and in-person equipment training and repair, we're focused on your business success every step of the way.