What is the medical tray sealing process?

Medical tray sealing involves applying a specific temperature for a specific amount of time under a specific pressure so that the lid and tray materials are bonded together. First, the rigid plastic tray, usually empty, is placed into a tool in the tray sealing machine. Then, an operator manually places the product in the tray and rests the lid stock on top. Next, the tray is shuttled into the tray sealing machine where the correct temperature, time, and pressure are applied. Once the sealing is complete, the tray exits the tray sealer and the operator unloads the finalized sealed package.

Achieving a good bond between the lid and the tray requires an exceptionally flat and parallel sealing platform, as well as the highly regulated and consistent application of temperature and pressure. To achieve a hermetic seal, it is critical for the both the lid and tray to conform and make intimate contact all the way around the perimeter of the tray. That means the tray sealer must accommodate for the inherent variability of lid and tray materials by being accurate and consistent.

The difference between tray sealing and pouch sealing

The process used for tray sealing is similar to the one used for pouch sealing; however, the two processes do differ in significant ways. For example, with pouch sealing, two flexible materials are bonded together. With tray sealing, a flexible material (lid) is bonded to a rigid material (tray). In addition, pouch sealing involves bonding a narrow band across the top of the pouch, while tray sealing involves applying consistent temperature and even pressure over a much wider area. In fact, comparing the average tray versus the average pouch, the amount of seal area is quadrupled. That means tray sealing requires a larger press area and greater control over the application of temperature and pressure.

How medical device tray sealing differs than other types of sealing

The most important difference between medical device tray sealing and other types of sealing is that the materials used for the tray and the lid must be able to be bonded together to create a package that can be sterilized and maintain sterility over the shelf life of the product. In many cases, it is also important that the tray is designed to immobilize the product. Tray sealers used to package medical devices feature very precise systems for controlling time, temperature, and pressure during the sealing process. In fact, this level of accuracy and repeatability is what separates medical device tray sealers from other types of sealers. For packaging equipment to be even considered capable of sealing medical trays, it must be validatable, meaning that the sealer must be verified to provide the same results repeatedly with very little to no deviation.

What is tray sealing?

Tray sealing is a packaging process that binds a flexible, die-cut lid to a pre-formed, rigid tray that contains whatever it is that needs to be packaged. Usually, the lid is made from thin material such as Tyvek, laminated foil, paper, or film, and the tray is made from a rigid or semi-rigid plastic such as PETG.

Tray sealing is commonly used for packaging medical devices, particularly when clamshell packaging or blister sealing are not applicable. Tray sealing prevents products from moving in the tray during shipping and creates a hermetic seal so that products can be stored and shipped under sterile conditions.

Types of materials used for tray sealing

Tray and lid materials are carefully selected based on their inherent properties and the specific needs of the products being packaged. For medical tray sealing, the most common lid stock is Tyvek, and the most common tray material is PETG—because both of these materials are well-suited for sterilization. Alternative tray materials may be used for products requiring specific vapor transmission rates or other internal atmospheric conditions ( e.g., HDPE offers a higher vapor barrier than PETG).

Likewise, some products may be light sensitive and require an opaque tray material, while others may need more protection during shipping and therefore may be best packaged in materials that can resist cracking if dropped. For lids, a manufacturer might opt for foil rather than Tyvek if the sterilization process is not a concern and there is a need for additional puncture resistance, more moisture control, or a light barrier.

Products shipped and stored in sealed trays

Tray sealing is commonly used in the medical device industry to package products that need to be shipped and stored under sterile conditions. These types of medical devices cannot be packaged using clamshells because clamshells rely on snap closures and cannot be hermetically sealed. By contrast, tray sealing completely bonds the lid to the tray, enabling a hermetic seal. In addition, these products are typically high-value medical devices, such as joint replacements and implants, that need to be packaged so that they are immobilized and yet readily accessible and presentable in medical settings. It is easiest to do this using a tray, rather than a flexible pouch. Sealed trays also provide better puncture resistance than clamshells or pouches.