The Medical Tray Sealing Process

The Medical Tray Sealing Process

Aug 2, 2021 | Blog, CeraTek, Medical Tray Sealer

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.

 

Tray Sealing 101

Jul 28, 2021 | Blog, CeraTek, Medical Tray Sealer

Ceratek Medical Tray Sealer

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.

 

How to Find the Right Vendor

Jul 19, 2021 | Blog, CeraTek, Medical Pouch Sealer

How to select a vendor for heat sealers for medical pouches

With so many types of heat sealers and ancillary features available today, the process of choosing for the right vendor can seem a bit daunting. Here are the key capabilities you need to look for:

First, it’s important to find a heat sealer vendor that has the ability to customize their equipment to meet your specific medical pouch sealing needs. Look for a company that can handle the design engineering in house so that they can tailor a solution to fit your production flow.

Second, it’s critical for you to find a heat sealer vendor that understands the industry requirements of validation and package testing. They should also be involved at the industry level through ASTM, AAMI, and other organizations such as the IoPP medical packaging subcommittee. The vendor you choose needs to understand not only where the industry is today, but also where it’s going, so that you can rest assured that you are getting the most up to date technology to meet your needs.

Third, look for a heat sealer vendor that has a strong field service engineering team. They need to be able to handle both remote and on-site service support, regardless of where your packaging operations are located throughout the world. Look for a vendor that will partner with you as your equipment supplier, complete with a field service engineering network that offers rapid support for all your medical pouch heat sealing needs.

Validating Heat Sealers

Jul 12, 2021 | Blog, CeraTek, Medical Pouch Sealer

Validation of heat sealers using IQ, OQ, and PQ

Heat sealers must be validated before they can be used in production. This validation is a three-phase process.

The first phase is the IQ, which stands for installation qualification. During the IQ, the medical device manufacturer verifies that the heat sealer was built to spec, has the needed utilities, and was installed properly.

The second phase is the OQ, or operational qualification. For the OQ, the medical device manufacturer must walk through all the control processes of the heat sealer and verify that it operationally functions every time as it should. The temperature control, pressure control, time control, recipe control, alarms and all other operational aspects must be verified.

The final phase is process qualification, or PQ. The PQ phase involves observing the heat sealer in combination with the medical pouch it’s going to seal, i.e., the actual heat sealing process. The IQ and the OQ are focused on the heat sealer itself. The PQ phase verifies that the heat sealer is delivering a repeatable process and that the medical pouch is sealing in a repeatable fashion. It confirms that the output is what it’s supposed to be.

Any heat sealer used for medical pouch sealing should be ISO 11607-compliant. ISO 11607 is a guidance document that is used to define many different aspects of sterile packaging. For example, for a piece of sealing equipment to be ISO 11607-compliant, it must have the ability to verify and alarm temperature, pressure, and time.

FDA approval of medical pouches

Just as medical products require FDA approval, medical packaging must also be FDA approved. Medical device manufacturers need to have their manufacturing and packaging processes regularly audited to ensure that they are using the proper equipment and that it has been validated and maintained properly. The FDA offers approval guidelines for medical manufacturers to follow, but it does not provide instructions.

The types of heat sealer options

Today’s heat sealers can come equipped with options that help with compliance and risk mitigation. Traditionally, medical pouch sealing has been mostly a manual operation. However, more and more medical device manufacturers are implementing automation and other features to minimize operator error and mitigate other risks.

For example, some heat sealers are not enabled to cycle until the product which is put into the package is confirmed by weight. Others are equipped with barcode readers, vision cameras, or other sensors that detect certain markings on a pouch to verify that it has been positioned correctly for sealing. The cycle will only begin if the medical pouch is properly oriented and located. In some cases, heat sealers come equipped with alarms to alert the operator of errors and that a pouch needs to be put into a quarantine bin before the next cycle can start. They can also have outputs designed to control conveyors that move a pouch to the next process based on whether or not there was a good or a bad cycle.

Features for printing are also becoming more popular. For example, inkjet printers or embossing type systems can be added to continuous band or a rotary band sealers so that the medical pouches are printed on as they are sealed. Embossers can also be added to jaw type heat sealers to emboss a fixed imprint into the pouch.

In addition, other ancillary equipment can be added to heat sealers to help operators work more efficiently. For instance, some heat sealers have a pouch opening system that will pull a pouch out of a magazine and present it to the operator in an open format. After the operator places the product into the pouch, the pouch opener releases the package so that the operator can seal it. Since operators working in a clean room are typically gloved, this type of pouch opening system can significantly increase throughput. Efficiency can also be improved using static elimination options, which range from an overhead ionizing fan blowing down on the assembly area to reduce the static field to static elimination chambers for the medical pouches to pass through.

How to Optimize Heat Sealers

Jul 5, 2021 | Blog, CeraTek, Medical Pouch Sealer

Medical pouch seals must be optimized to maintain sterilization

In the medical device manufacturing field, sterility is a fundamental concern. If a medical device needs to be sterile for use, it must be delivered to the end user in a sterile condition. Otherwise, the product is worthless. The pouch materials and the heat sealing conditions must be carefully determined so that the seal can both sustain and maintain sterilization.

Heat seals are created by delivering a specific temperature, under a specific pressure, for a specific amount of time. When designing a package and defining its optimal sealing parameters, manufacturers run a DOE (Design of Experiments) to determine what the low and high points are for temperature, pressure, and dwell time.

Then, they use this data to create a 3D matrix, where the center point marks the optimal temperature, pressure, and time. They also identify a process that has a range above and below the temperature set point, time set point, and pressure set point, where an acceptable, although not optimal, seal can still be achieved. This creates a window for alarming around the optimal seal parameters where the heat sealer can operate.

The more consistent a heat sealer is in delivery of temperature, pressure, and time, the more repeatable the seal strength will be—and the more repeatable the seal strength is, the tighter the manufacturer’s statistical control over that packaging process. Tight statistical control is important. If a manufacturer has to defend their packaging process during an FDA audit, tight statistical control will give the FDA more confidence in the development of the packaging process.

Manufacturers need to validate their heat sealers to verify that they deliver the same seals in a repeatable manner cycle, after cycle, after cycle. These processes must be minimally affected by operators, and they need to deliver the designated temperature, pressure, and dwell time repeatedly and reliably.

How to measure medical pouch heat seal integrity

There are a few different ways to verify seal integrity and quality. The most common way is to measure peel strength using a tensile tester. This process involves clamping a sample of the seal into the two plates/grippers of a tensile tester, and then measuring the force required to separate the seal. The goal is to achieve a repeatable seal strength, so this test will typically be conducted multiple times. Another way to test seal integrity is to use a burst test, where the inside of the pouch is increasingly pressurized until it bursts and/or the sterility is compromised. Medical device manufacturers use a Process Capability Index called CpK, to describe how accurate and repeatable the seal strength is over the course of a sample lot.

Recently, the FDA has begun to focus more than ever before on the statistical control that medical device manufacturers have on their processes. This means medical device companies are being driven to have a higher process capability, or Cpk. CpK indicates how accurately a medical device manufacturer can control medical pouch seal strength, and how repeatable their processes are. It is imperative for medical device manufacturers to identify the sources of variability in their heat seal processes, and then control those variables with precise and reliable systems for temperature, pressure, and timing.

Different heat sealers run differently. For example, in an impulse sealer, heat can build up in the bar that supports the wire, and that can change the amount of heat that packages is exposed to over the course of a production run. This type of variability can result in peel strengths that change throughout the production run. This is one of the reasons why it is more difficult to achieve a high CpK with an impulse sealer compared to a constant heat sealer. With a constant heat sealer, the seal heat is stable, leading to a high CpK.  

Keep in mind that temperature, pressure, and dwell time are all interrelated. Of these, the two most critical factors in seal strength are temperature and dwell time. Pressure is the least impactful, because once intimate contact is achieved, increasing seal force, or seal pressure, will not have a big impact until the pressure level increases to the point of squeezing the adhesive layer out of the seal. So seal force is the least impactful, once you’ve achieved intimate contact.

Throughput objectives can be a factor, as well. If a medical device manufacturer wants to maximize throughput, they may increase temperature and decrease dwell time, because they want to get more medical pouches sealed faster. Another manufacturer may want more process stability, and so they may opt for a lower temperature with a longer seal time. The ultimate goal of either throughput or stability will drive the sealing process toward low temperature with high time, or low time with high temperature.