Why is Seal Strength so Important in Medical Device Packaging?

Dec 15, 2022 | Blog, CeraTek

heat sealing machineWhy is Seal Strength so Important in Medical Device Packaging?

In the realm of medical device packaging, an often-underestimated factor emerges for preserving product efficacy and patient well-being: seal strength.

Behind the scenes of sterile barriers and materials lies a critical element that wields influence far beyond its seemingly modest role.

Dive into the multifaceted significance of seal strength in medical device packaging and explores its implications for safeguarding the integrity of medical products.

What are the key attributes that makeup Seal Strength: Let’s Dive In!

  • Tensile Strength: Tensile strength refers to the force required to pull apart the sealed components in opposite directions. It measures the integrity of the seal under stress, indicating how well the seal can resist forces that might occur during transportation, handling, or accidental impacts.
  • Peel Strength: Peel strength measures the force required to peel back the sealed layers in a direction parallel to the seal interface. This attribute is particularly important for packages that are opened by peeling, such as pouches with easy-tear features. Adequate peel strength ensures that the package can be opened without compromising the integrity of the seal.
  • Burst Strength: Burst strength assesses the pressure required to rupture the seal, simulating conditions like pressure changes during air travel or other environmental stressors. It ensures that the seal remains intact even under increased pressure differentials.
  • Shear Strength: Shear strength evaluates the force needed to slide one sealed layer over another. This attribute is essential for packages that might experience sliding forces during transportation or handling. A strong shear strength prevents the layers from separating unintentionally.
  • Environmental Resistance: The seal’s ability to resist degradation when exposed to external factors like moisture, temperature fluctuations, light, and chemicals is crucial. It ensures that the seal maintains its strength over the device’s intended shelf life.
  • Consistency and Reproducibility: Seal strength should exhibit consistent and reproducible results across different batches of packaging. Manufacturers need to ensure that the seal strength remains within a specified range to guarantee uniform product quality.
  • Material Compatibility: The materials used for the packaging and the sealing layer should be compatible to achieve optimal seal strength. Mismatched materials might lead to weak seals that can easily break or fail.
  • Sealing Process Control: The method used to create the seal, such as heat sealing, ultrasonic sealing, or adhesive sealing, plays a crucial role in determining the seal’s strength. Manufacturers need to have precise control over the sealing process parameters to achieve consistent results.
  • Regulatory Compliance: Regulatory standards often define acceptable seal strength criteria. Meeting these criteria is essential to ensure that the packaging complies with industry regulations and can withstand the challenges of the healthcare supply chain.

Three Reasons Seal Strength is of Utmost Importance in Ensuring Patient Safety

  1. Contamination Prevention: The primary purpose of medical device packaging is to maintain the sterility of the enclosed products. A strong seal ensures that the package remains impervious to external contaminants, such as microorganisms and particulate matter. Inadequate seal strength can lead to breaches in the packaging, potentially allowing harmful agents to enter and compromise the sterility of the medical devices. This can result in serious infections and health risks for patients.
  2. Product Integrity and Performance: Medical devices often contain sensitive components or materials that can be negatively affected by environmental factors such as moisture, oxygen, and light. A robust seal acts as a barrier, protecting the contents from these elements that could compromise the device’s functionality or structural integrity. A compromised seal might lead to damage, degradation, or alteration of the device, rendering it ineffective or unsafe for use.
  3. User Confidence: Healthcare professionals and patients place their trust in medical devices and the manufacturers behind them. A reliable seal reinforces this trust by signaling that the product inside has been meticulously protected and remains uncontaminated. User confidence is essential for the effective adoption and usage of medical devices, and a strong seal contributes significantly to this assurance.

The complex nature of medical device packaging demands a deep understanding of materials, manufacturing processes, and quality assurance protocols.

A compromised seal could lead to devastating consequences. Thus, achieving optimal seal strength is not just a technical requirement but also a moral, ethical, and legal obligation.

We recognize the weight of this responsibility and are committed to providing solutions that ensure the highest standard of seal strength. Our expertise in this field stems from years of dedicated research, technological innovation, and collaboration with industry experts.

Our team is driven by a shared mission to advance the reliability of medical device packaging, constantly pushing the boundaries of what’s achievable. Contact us to learn more.

Safeguarding Lives: The Crucial Role of Sterile Packaging in the Medical Field

Aug 15, 2022 | Blog, CeraTek

surgeon using medical devices in an operating roomIn the intricate realm of modern medicine, one of the most critical yet often overlooked elements is sterile packaging. While the remarkable advancements in medical technology and treatments grab headlines, the importance of maintaining sterility through proper packaging cannot be understated.

Sterile packaging is not just about aesthetics; it plays a pivotal role in preventing infections, complications, and even fatalities.

Let’s explore the importance of sterile packaging within the medical realm and its role in preserving and enhancing human lives.

Why is Sterile Packaging Important?

Sterile medical packaging involves creating an environment free from microorganisms, ensuring that medical equipment, instruments, and supplies remain uncontaminated from manufacturing to their final use. This meticulous process involves using specially designed materials and techniques that inhibit the growth of bacteria, viruses, and fungi.

The ultimate goal is to provide healthcare professionals with tools and products that are entirely free from potentially harmful pathogens, reducing the risk of infections and complications in patients.

Preventing Infections

In healthcare settings, where patients are already vulnerable due to illness or injury, infections can be particularly devastating. Sterile packaging acts as a barrier, shielding medical devices and instruments from contaminants that could otherwise compromise patient health.

Surgical site infections, bloodstream infections, and other healthcare-associated infections can lead to

  • Prolonged hospital stays
  • Increased medical costs
  • Mortality

By utilizing sterile packaging, medical professionals can significantly reduce the incidence of these infections, ultimately saving lives and improving patient outcomes.

Enhancing Surgical Procedures

Surgical interventions are intricate procedures where precision and sterility are of primary concern.

Surgeons rely on a wide array of tools and equipment to perform procedures that range from routine to complex. Sterile packaging ensures that these instruments are devoid of any harmful microorganisms, reducing the risk of post-operative infections.

A meticulously packed sterile instrument tray contributes to a seamless surgical process, allowing surgeons to concentrate on the procedure itself rather than worrying about contamination issues.

Protecting Implantable Devices

Implantable medical devices, such as pacemakers, joint replacements, and stents, have revolutionized the treatment of numerous conditions. However, if these devices are not packaged and handled with stringent sterilization practices, they can introduce infections or complications when implanted within the body.

Proper sterile barriers of these devices ensure that they remain free of pathogens, minimizing the potential for adverse reactions and contributing to the longevity of the implants.

Emergency Preparedness

In times of crisis, healthcare systems are strained to their limits. Having access to pre-packaged sterile medical supplies becomes even more critical in these scenarios.

Sterile packaging allows for quick and efficient distribution of medical products to emergency response teams and healthcare facilities. These supplies can be readily deployed to treat patients in dire circumstances, preventing secondary infections and saving lives amidst challenging conditions.

Ultimately, sterile packaging may not be as glamorous as cutting-edge medical technologies, but its impact on patient outcomes cannot be overstated. By preventing infections, enhancing surgical procedures, protecting implantable devices, and aiding emergency preparedness, sterile packaging plays a vital role in saving lives within the medical field.

As we celebrate the remarkable strides in medical science, let’s also acknowledge the significance of the seemingly simple act of maintaining sterility.  Please contact us to learn more about how to safeguard lives and promote the well-being of patients around the world.

Guide to Applying a Vacuum or a Vacuum and Gas Flush to a Pouch

Mar 9, 2022 | Medical Pouch Sealer

Pouch Sealing

Your Step-by-Step Guide to Applying a Vacuum or a Vacuum and Gas Flush to a Pouch

Many manufacturers have questions about applying a vacuum only or a vacuum and gas flush to a pouch. In this blog post, we’ll explain:

  • The most common applications for applying a vacuum or a vacuum and gas flush to a pouch
  • How pouch materials impact which application is optimal and the best methods for working with common pouch material combinations
  • The process for using a nozzle to apply a vacuum or a vacuum and gas flush to a pouch
  • The process for using a chamber to apply a vacuum or a vacuum and gas flush to a pouch

Understanding these fundamental concepts and best practices will help you determine which application is optimal for your use case.

How to apply a vacuum or a vacuum and gas flush to a pouch

A vacuum or a vacuum and gas flush can be applied to a pouch in one of two ways—either by using a nozzle sealer or by placing the pouch in a chamber sealer. The optimal method is dependent on the type of pouch materials being used, whether vacuum only or vacuum and gas flush is required, and other factors.

A nozzle sealer is most commonly used for:

  • Volume reduction. The goal of volume reduction is to remove enough air from the pouch to prevent it from popping during high altitude shipments or so that it can fit into a box or secondary container. Because volume reduction applications are considered a “gross” vacuum process, either time-based or level-based programs can be used; however, a time-based mode is the most popular. Product sensitivity can play a role in how much volume should be drawn out of the pouch.
  • Product immobilization. In certain cases, it is critical to remove air from the pouch so that the product being packaged is immobilized. Product immobilization applications are considered a “gross” vacuum process so either time-based or level-based programs can be used; however, since the final internal volume in the pouch is a function for immobilizing the product, operating in level mode provides greater reassurance that the appropriate internal pressure has been achieved to restrain the product in the pouch. Product sensitivity can play a role in how much volume should be drawn out of the pouch.
  • Reducing O2 or relative humidity (RH). Multiple vacuum/flush cycles can be programmed to progressively reduce the O2 or RH in the pouch. While modifying the atmosphere in the pouch can be programmed as a time-based function, vacuum and flush levels are critical in adequately and repeatedly reducing oxygen or relative humidity. That is why most applications requiring reduced O2 or RH operate in level mode. The flexibility of the pouch materials and their ability to conform around the geometry of the nozzle can affect the achievable goal, even with multiple cycles.

A chamber sealer is most commonly used for:

  • Achieving ultra-low residual O2 Vacuum and gas flush applications requiring an extremely low residual oxygen level (below 1%) require a chamber sealer. A nozzle sealer cannot be used for these applications because of the “leak points” around the nozzle while it is processing the pouch. For ultra-low residual O2 level applications, the entire chamber atmosphere is modified and level setpoints as low as 1mbar can be programmed. A dwell time at each step can be programmed to maintain the level for the specified amount of time and allow the product to acclimate.
  • Sealed header pouches. Sealed header pouches that need to be vacuumed and/or flushed must use a chamber sealer because it is physically impossible to insert a nozzle into a hermetically sealed and terminally sterilized pouch. In these cases, the atmosphere inside the pouch is modified by vacuuming and/or flushing through the Tyvek window on the pouch. For this type of application, a program that has the flexibility to allow multiple steps in either direction (vac-vac-vac-flush-vac-flush-flush, for example) with programmable dwell times at each step will provide the control required to vacuum the pouch without bursting it or to flush the pouch without crushing the product or pinching off the header. The atmosphere inside the chamber can change significantly faster than the interior of the pouch because the header acts as a filter, hampering the flow of air and/or gas into and out of the pouch. A dwell time at each vacuum or flush step can provide the necessary time for the pouch to acclimate to the chamber atmosphere before the next process step begins.

Pouch materials impact whether a nozzle or chamber should be used for applying a vacuum or a vacuum and gas flush

The pouches used for vacuum (no gas flush) and vacuum and gas flush applications are typically made from laminated or mono-layer flexible materials including—but not limited to—Tyvek, coated foil, and film. The specific materials used impact whether a nozzle or chamber is optimal, and these are the most common pouch material combinations and the method that works best for applying a vacuum and/or gas flush to each one:

  • Foil/Foil: Nozzle or chamber
  • Film/Foil: Nozzle or chamber
  • Film/Film: Nozzle or chamber
  • Foil/Tyvek Header: Chamber
  • Film/Tyvek Header: Chamber
  • Film/Tyvek: Nozzle

Other factors to consider before deciding to use a nozzle to apply a vacuum or a vacuum and gas flush to a pouch

A number of different factors should be considered before deciding to use a nozzle sealer to apply a vacuum or a vacuum and gas flush to a pouch. Here is a sampling of the top concerns:

  • Headspace. Since using a nozzle involves employing a clamp between the guarding and the sealing die, the pouch must have sufficient “free” material (i.e., headspace) for loading into the sealer.
  • Nozzle length. In order to be able to load the pouch over the nozzle, the nozzle must extend out of the sealer at least ½” resulting in nozzle penetration into the pouch of typically at least 1½” for constant heat sealers.
  • Product sensitivities. If the nozzle must not come into contact with the product, the pouch length must be sized appropriately to allow the product to remain safely distant from the nozzle.

Other factors to consider before deciding to use a chamber to apply a vacuum or a vacuum and gas flush to a pouch

Before deciding to use a chamber to apply a vacuum or a vacuum and gas flush to a pouch, it is important to consider factors such as:

  • Immobilizing the pouch. It is critical to immobilize the pouch during the vacuum and flush process. The air inside the chamber can become turbulent, and if the pouch shifts out of alignment with the seal bar, the pouch will not be sealed correctly.
  • Cycle time. The cycle time when using a chamber sealer will always be longer than when using a nozzle sealer because of the volume of air that is being modified. A nozzle sealer is modifying only the interior of the pouch. By contrast, a chamber sealer is modifying the volume of the entire chamber and the pouch. Additionally, processing a header pouch for a low residual oxygen level application requires the most time and may require multiple vacuum/flush steps with dwell times at each step.
  • Window for visibility. Using a chamber sealer that has a window for viewing the pouch as it is being processed can have enormous benefits. A window allows visibility into the process and enables the operator to monitor how the pouch is behaving during the vacuum, flush, sealing and repressurizing process.

The process for using a nozzle sealer to apply a vacuum or a vacuum and gas flush to a pouch

Using a nozzle sealer to apply a vacuum or a vacuum and gas flush to a pouch is a relatively straightforward process involving eight distinct steps:

  1. Bring the nozzle into the load position
    The nozzle used to apply a vacuum or a vacuum and gas flush to a pouch is like a snorkel or “straw.” In the first step of this process, the operator presses a foot switch that brings the nozzle into the load position.
  2. Load the pouch over the nozzle and slide it into the seal area
    With the nozzle in the load position, the operator places the pouch over the nozzle and slides it into the seal area.
  3. Close off the pouch around the nozzle
    Next, the operator presses the foot switch a second time, bringing a soft-faced clamp down to close off the pouch around the nozzle.
  4. Initiate the vacuum process, followed by gas flush, if needed
    Once the pouch is closed off around the nozzle, the vacuum process can begin. If a gas flush process is programmed, the gas will flush the pouch upon completion of the first vacuum process. Additional vacuum and gas flush cycles can be programmed depending on the application requirements.
  5. Apply final cycle
    The cycle can be programmed to end after a flush step, leaving a “pillow effect” in the pouch, or it can be programmed to end after a vacuum step, drawing the pouch down around the product.
  6. Retract nozzle while clamp is still engaged
    Once the vacuum/flush cycle has fully completed, the nozzle retracts from the pouch while the clamp is still engaged.
  7. Actuate seal bar and seal the pouch
    After the nozzle is clear of the seal area, the seal bar actuates and seals the pouch.
  8. Releasing the pouch from the sealer
    In the last step of the process, the seal bar and the clamp open, releasing the pouch from the sealer.

The process for using a chamber sealer to apply a vacuum or a vacuum and gas flush to a pouch

Using a chamber sealer to apply a vacuum or a vacuum and gas flush to a pouch is a relatively straightforward process involving eight distinct steps:

  1. Load the pouch onto a platform in the chamber
    When a chamber sealer is used to apply a vacuum or a vacuum and gas flush to a pouch, the process begins when the operator loads the pouch onto a platform inside the chamber sealer.
  2. Close the lid and apply the vacuum
    Next, the operator closes the lid of the chamber sealer and initiates application of the vacuum. The entire volume inside the chamber is vacuumed until the programmed level is reached.
  3. Initiate the gas flush
    The gas flush process begins after the initial vacuum step(s) are completed and flushes the entire chamber to the programmed setpoint.
  4. Apply additional vacuum and gas flush cycles as needed
    Additional vacuum and gas flush steps can be programmed to achieve even lower residual oxygen levels.
  5. Shuttle the pouch into the seal area and apply the seal
    Once the vacuum/gas flush process is completed, the pouch is shuttled into the seal area and the seal bars close, sealing the pouch.
  6. Shuttle the pouch back to the load position
    After the seal dwell timer has elapsed, the pouch is shuttled back out into the load position.
  7. Repressurize the chamber and open the lid
    Next, the chamber repressurizes back to atmosphere and the lid opens.
  8. Remove the pouch from the chamber
    Finally, the operator removes the pouch from the chamber.

This blog post covered several of the primary issues you need to consider when determining how best to apply a vacuum or a vacuum and gas flush to pouch. For more information and to discuss the details of your particular application, please contact us.

Pouch Sealer Frequently Asked Questions

Nov 28, 2021 | CeraTek, Medical Pouch Sealer

How does a CeraTek pouch sealer create a seal?

A CeraTek pouch sealer is designed to seal a package made from laminated or mono-layer flexible materials, and it creates a seal by applying heat and pressure to the pouch for a set amount of time. A pouch like this is created by bringing two webs of material together and sealing them on three sides, leaving the fourth side open. The product that needs to be packaged is inserted into this opening and then the pouch is inserted into the sealing machine. The CeraTek pouch sealer applies the temperature, pressure, and time required to activate a sealing adhesive which bonds the two layers of material together, creating a seal.

What are the main process variables associated with pouch sealing using a CeraTek sealer?

The main process variables associated with pouch sealing using a CeraTek sealer are time, temperature, and pressure. All three of these process variables are required to seal a pouch effectively.

How are time, pressure, and temperature controlled and monitored?

The three process variables—time, pressure, and temperature—are controlled through the CeraTek pouch sealer’s HMI. An operator can use the setup screens to program the time, temperature, and pressure based on the desired sealing process. These parameters can be changed for different materials and/or different pouch sizes.

What is the maximum temperature that a CeraTek pouch sealer can be set to?

The maximum temperature that a CeraTek pouch sealer can be set to is 400 degrees Fahrenheit for the top and bottom heat. Some pouch sealer models only use bottom heat, while others apply heat from both the top and bottom dies. If the pouch sealer has internal sensors, then the bottom heat maximum is 200 degrees Fahrenheit. Using temperatures that exceed these maximums can accelerate the wear of parts and increase maintenance costs.

What type of pouches can be sealed on CeraTek pouch sealers?

CeraTek pouch sealers can seal pouches made from a variety of different materials, including LDPE, nylon, Tyvek, foil, and many others. Our sealers are compatible with gusseted pouches, as well as with those that have headers or ones that are made from two different types of materials. If there are any question about compatibility, the experts at CeraTek are happy to test your materials and pouch designs on our equipment at our factory. The main requirement to keep in mind is that the pouch being used must be sealed on three sides. Then, the CeraTek sealer creates the fourth and final seal on the pouch.

When is Tyvek a better choice than foil?

Tyvek is a better choice than foil for products that must undergo additional sterilization processes after packaging. Tyvek is made of 100% high density polyethylene fibers, and it is manufactured to be “breathable,” yet impervious to microbes. That means Tyvek pouches can undergo sterilization processes using EtO gas, gamma radiation, electron beams, hydrogen peroxide, and steam. For example, in the case of a medical pouch made of Tyvek, the EtO gas passes through the Tyvek material, killing any contaminating microorganisms that are inside the package. Then, the pressure is relieved, as regular air is pumped back into the chamber, dispersing the EtO gas. As long as the medical pouch remains sealed, the contents are sterile. Foil is a non-breathable material, and pouches made from foil cannot be sterilized in this way.

Are CeraTek pouch sealers able to be validated?

Yes, CeraTek pouch sealers are validatable. Sealing parameters such as time, temperature, and pressure can be validated through the output ports on the side of the machine. The operator can use these ports to plug in a calibrated test instrument and retrieve the readouts of time, temperature, and pressure and confirm that the machine is functioning properly.

Are CeraTek pouch sealers ISO 11607 compliant?

Yes, CeraTek pouch sealers are ISO 11607 compliant. This compliance means that the accuracy and repeatability of the sealing process can be verified. For example, pouch sealing parameters such as time, temperature, and pressure can each be validated through their own specific output ports on the side of the machine. Each individual thermocouple has an output port for validation of the temperature readings. Likewise, there is a pressure output port and a timer output port.

Does CeraTek perform testing on pouch samples?

CeraTek has an in-house tensile tester which collects data on the strength of the seal, and we are happy to use this for testing customer samples at no cost. We can also help customers connect with others who can perform additional assessments, such as creep, burst, and dye penetration tests.

Does CeraTek offer different width sealing dies?

Yes, CeraTek offers sealing dies of different widths. The most common width is three-eighths inch, but we also offer standard one-eighth, one-fourth, one-half, and one inch sealing dies. We can also custom-make dies for requirements outside of our standard widths. Each sealing process has its own die requirements and validation parameters, so it is critical to make sure the die being used is the correct width.

When is it important to vacuum air out of a pouch prior to sealing it?

There are a few different reasons why it may be important to vacuum air out of a pouch before sealing. One of the most common reasons is to accommodate altitude changes for packaged products that are going to be shipped by air. If the pouch is sealed with too much air in it, and the altitude increases, the pouch could potentially burst. Another common reason to remove air from a pouch is to reduce its bulkiness so that it fits better into secondary packaging. CeraTek sealers can vacuum out air from a pouch through a nozzle that extends from the machine. The operator simply loads the pouch around the nozzle, initiates the cycle, and the nozzle vacuums out the air. Once the vacuum cycle is complete, the nozzle retracts and the sealing cycle begins.

How much compressed air needs to be supplied to a CeraTek pouch sealer?

For optimal pouch sealing, CeraTek recommends supplying 15 PSI above the desired pressure set point, up to a maximum of 125 PSI. For example, if the desired pressure set point is 50 PSI, we recommend supplying at least 65 PSI to the CeraTek pouch sealer. There are onboard air accumulator tanks within the CeraTek machine that reduce the risk of any pressure drops during the sealing cycle.

How is compressed air used on a CeraTek sealer?

The manufacturing facility supplies air to the CeraTek sealer’s onboard air accumulator tanks, and a pressure regulator on the machine ensures that the pressure supplied is accurate (i.e., it is not under- or overpowering). The air accumulator tanks initiate and perform the sealing cycle, driving the cylinders up and down to create the pressure applied to the seal. Incorporating these tanks into the sealer’s design helps mitigate the risk of fluctuation in the air supply. For instance, if the manufacturing facility has multiple machines on the same airline, the pressure flow across that line could vary. The CeraTek sealer’s air accumulator tanks significantly mitigate that risk.

What is Process Capability (Cpk)?

Nov 19, 2021 | CeraTek, CPK

What is Process Capability (Cpk)?

Cpk is shorthand for the term “process capability index.” It is a statistical measure of process capability that engineers use as a tool to determine how accurately a target is met.

Why is Cpk such an important parameter with sealer heating technology?  

Cpk is used throughout the sealing process as a way to measure how accurately and repeatably seals are being applied. Heat sealers apply temperature, pressure, and time to create seals of a specified, targeted seal strength. Cpk is used to determine how accurately that seal strength is reached and how consistently it is reached over time.

What type of industries are focused on Cpk?  

Since Cpk is a statistical measure of process capability, it can have application in any industry where defined processes are used repeatedly. Cpk is particularly useful in packaging because it can be used to measure how accurately and repeatedly a sealing machine applies a seal.

Why type of medical products are packaged with pouch sealers and why is Cpk important in those packaging processes?

Pouch sealers are used to package high value medical products that need to be kept sterile. These products run the gamut from single-use, disposable medical devices, such as catheters and stents, to devices that ultimately become a permanent part of a patient’s anatomy, such as the components used for hip replacements and the screws and rods that can be used to repair bone fractures. Pouch sealers are also used to package certain surgical instruments, although in these cases, the instruments are cleaned, sterilized, and packaged in pouches more than once.

When packaging medical products that must remain sterile, it is critical to consider Cpk. That is because Cpk helps determine how accurately and repeatedly a heat sealer has applied the seal that will maintain sterility. It is vital to know that the packaging seal has been applied according to specifications; otherwise, there is little assurance that the product will remain sterile, and the lives of end users could be at risk.

 What type of machines are used to seal medical device pouches?

 Medical device pouches can be sealed in a variety of different ways, depending on the type of pouch material being used, the sealing temperatures needed, and other factors. Broadly speaking, these medical grade heat sealers are either constant heat sealers or impulse heat sealers.

 Impulse heat sealers

The heating element in an impulse heat sealer is a very thin wire that can heat up and cool down quickly. It generates an “impulse” of heat, allowing the die to rapidly reach temperature and then cool down, all while under pressure. Impulse heat sealers are typically used for either the high temperature sealing or welding of mono-layer materials. They are usually not used for sealing pouches made from multi-layer materials because when the temperature fluctuates between heating and cooling every cycle, it is difficult to maintain accurate temperature control.

 Constant heat sealers

A constant heat sealer has a heater embedded into its aluminum ceiling die. The operator sets this heater to a certain temperature and turns it on. After a few minutes, the heat is evenly distributed across the ceiling die, and the die will remain at this temperature until the sealer is turned off. Because they maintain one, consistent temperature, constant heat sealers are the easiest heat sealers to validate. They also provide the most stable, repeatable sealing process and require less ongoing maintenance than other types of sealers. Most of the seals used in sterile medical pouches are produced by constant heat sealers.

A continuous band or rotary band heat sealer is a type of constant heat sealer that uses opposing bands to carry pouches through the heat sealing process. The operator feeds the leading edge of the pouch into the sealer, where it is captured by the bands and pulled through to the section where heat is applied. The heat brings the materials to the melt point and seals them together, and then the bands continues to pull the pouch through the sealer to an unheated section where cooling occurs. The cooled pouch then emerges from the machine. Interestingly, a continuous band or a rotary band heat sealer offers the benefits of both constant and impulse heat. The actual pouch sealing is done with constant heat, which is a very stable temperature, but then the pouch is pulled along to an area where there is no heat, enabling it to cool under pressure.

What is the difference between a weld seal and a peelable seal?

Medical pouches are sealed using either a weld seal or a peelable seal. For a weld seal, the two layers of pouch material are annealed, or welded, together. This creates a seal that is quite strong. While a weld seal is optimal for certain applications, it can introduce problems when the pouch needs to be opened. At times, opening a weld seal can result in tearing the pouch, creating fibers or very small particles that could compromise the sterility of the product, the pouch, or the environment where the pouch is being opened. A peelable seal is different because it is strong enough to withstand handling and shipping, but not so strong that it presents problems when the pouch needs to be opened. As the name implies, a peelable seal can be easily peeled open. It must be tested for both strength and peelability, and then the heat sealer must be set for those parameters of temperature, pressure, and time. The sealing process must be very accurate and repeatable to ensure that each pouch maintains sterility and can be easily peeled open at the time of use.

What sealing parameter has the most impact on Cpk?

The sealing parameter that has the most impact on Cpk is heat, whether that is the temperature set point or the duration of time that that pouch is exposed to the heat. The temperature must be consistent and repeatable at the defined set point. Any variation widens the average and lowers the Cpk. Ideally, the Cpk is as high as it can be with a very tight average. That is why it is critical to reduce variation in all heat sealer set points, especially temperature. Temperature can be difficult to control because of fluctuations related to factors such as air movement, heat sinks, and pouch materials.

How do the upper and lower dies on a heat sealer vary with regard to heat loss and gain?

The upper die on a constant heat sealer is constantly battling heat loss. During the sealing cycle, each time a (heated) upper die makes contact with an (unheated) lower die, it loses some heat. That means it is essential for the upper die to have a very tight heating profile and constantly adjust to maintain temperature over time. By contrast, an unheated lower die will continually gain heat throughout a sealing run. That means, as the run progresses, the pouches toward the end of the run could be exposed to different sealing conditions than those at the start of the run. Differences like these can be accentuated by the speed and attention of the operators using the sealers. Using a heat sealer with a lower heated die that is fully controlled and alarmed can eliminate much of this variability and improve Cpk.

 How can a heat sealer with a lower heated die help the integrity of the sealing process and improve Cpk?

 Cpk improves as variables are eliminated. Adding temperature regulation to the lower die gives the operator control over yet another variable in the entire sealing process. Our pouch sealer with a lower heating die is becoming increasingly popular because customers are finding that having a controllable, heated lower die allows them to improve Cpk.

What are the factors that affect Cpk for medical pouch sealing?

Cpk for medical pouch sealing is affected by a wide variety of factors, ranging from how much temperature, time, and pressure is applied during the sealing process to which materials are used to create the pouch. In addition, Cpk can be affected by how the desired seal strength is initially determined and tested over time. After all, it is important that any seal strength testing is repeatable and accurate, as well. Weighing all of these different factors can be daunting. That is why it is so important to work closely with the manufacturer of your heat sealer. They can help you develop a full understanding of the heat sealing process and the most effective ways for you to improve Cpk.