Validating Heat Sealers

Industry groups, heat sealer suppliers, and other experts can help packaging engineers meet FDA and ISO validation requirements.

by Daphne Allen, Editor

If you seal flexible or rigid packaging, chances are you use a heat sealer. There is also a pretty good chance that at one point you have struggled with the task of validating the sealing process.

You are not alone. Process validation, mandated by both FDA's quality system regulation (QSR) and the ANSI/AAMI/ISO document 11607, "Packaging for Terminally Sterilized Medical Devices," can be complicated and time-consuming. And, worse still, device packagers are often left to themselves to figure it out.

But you can find help. Industry groups such as the Association for the Advancement of Medical Instrumentation and the Flexible Packaging Association are helping packagers make sense of the regulations and find appropriate ways to validate their heat-sealing processes. Heat-sealing equipment suppliers are also lending a hand, offering a wide range of fully validatable units with a host of other options that help make a packager's job a little easier.


It isn't hard to find references that state process validation is necessary. Published in the Federal Register in May 1987, FDA's guidance document "General Principles of Process Vali-dation" states that the agency expects both the process and process controls to be validated. Most recently, the QSR, published in the Federal Register in October 1996, states in section 820.75 that "where the results of a process cannot be fully verified by subsequent inspection and test, the process shall be validated with a high degree of assurance and approved according to established procedures."

Packaging Aids Corp.'s Med Vac heat sealers can be used in a cleanroom.


Even AAMI, in its 1996 Quality System Compendium, GMP Requirements & Industry Practice, reiterates FDA's edict on process validation. But it goes further, stating that, even though FDA has not "officially published guidelines for defining processes that require validation," sealing is one of many processes "that traditionally have been considered by FDA to require validation."

In the compendium, AAMI also outlines typical approaches used by industry for process validation. For packaging operations, it describes what parameters are typically validated. These are "temperature, dwell time, pressure, ultraviolet energy level, and the speed of the conveyor through the ultraviolet tunnel or form-fill-seal machine."

Calling forming and sealing the most critical processes, ISO 11607 states in section

Essential processing parameters shall be evaluated. These include, but are not limited to, a) temperature; b) pressure/vacuum, including rate of change; c) dwell time (line speed); d) energy levels/frequency (radio frequency/ultrasonic); e) torque limits for lid/cap closure systems.

According to some heat sealer suppliers, these documents leave their customers confused. Paul Irvine, president of Emplex Systems Inc. (Scarborough, Ontario, Canada), a manufacturer of band sealers, says that "ISO 11607 is vague—it is an interpretive document." Adds Charlie Webb of Fuji Impulse America (Wrightwood, CA): "There isn't a good boilerplate for our customers to go by. There needs to be something that everyone can share."

Tim Early, formerly a packaging engineer and now a marketing specialist at DuPont Nonwovens (Wilmington, DE), agrees that there are no "straightforward checklists or cookbook methods to validation." But he says that the authors of ISO 11607 intended to state the requirements and not the how-tos of validation because of the wide range of qualification and validation methods currently used by industry.

Early recommends that packagers create an equipment installation qualification (EIQ) protocol that defines their requirements for machine qualification prior to beginning process development. Items that may be considered during the EIQ process include:


  • Correct electrical hookups and connections.


  • Proper air pressure.


  • Seal tooling compatibility.


  • Thermal profile of the sealing bar or platen.


  • Dwell time and temperature readout verification.


  • Proper guarding and safety review.


  • Calibration requirements, frequency, and methods.


  • Software validation.


  • Training of associates, including technicians, set-up personnel, and equipment operators.


  • Maintenance procedures.


  • Spare parts list.


  • Cleaning requirements and methods.

To further help packagers, the Sterile Packaging Manufacturers Council (SPMC) of the Flexible Packaging Association is preparing a guideline for packaging manufacturers that will be titled "Protocol for Validation of Package-Manufacturing Equipment." According to Jackie Daly Johnson, COO of Beacon Converters (Saddlebrook, NJ) and part of SPMC's technical task group, the guideline is currently in its draft form and should be available in 1999.

In addition, AAMI is preparing a technical information report (TIR) meant to serve as guidance for ISO 11607. The TIR, which should be published by the end of 1998, addresses packaging forming and sealing.

The Institute of Packaging Professionals (IoPP) is also helping. IoPP has formed a committee to establish and publish validation guidelines. Stay tuned for ones on specific types of packaging machines.

Another resource is a validation expert. Accu-Seal (San Diego), a provider of tabletop impulse sealers, teams up with the consultancy Precision Measurement Equipment Services (Tustin, CA) to offer clients both equipment and validation expertise. "We help customers determine a calibration schedule and make recommendations based on the application," says Larry Brown, lab manager at Precision Measurement Equipment Services.


To help packagers meet these regulatory requirements, many suppliers of heat-sealing equipment have made their systems easy to validate. According to Johnson at Beacon, "Devices that are to be validated must be calibratable." Many suppliers are meeting this need by providing units that allow users to customize the three elements relevant to heat sealing, which are time, temperature, and pressure. Emplex's Irvine says that many of his clients want "upfront calibration," so he supplies heat sealers along with calibration units.

Ray Johnson of Doboy Packaging Machinery (New Richmond, WI) says that Doboy's stand-alone band sealers are supplied with a variety of settings for heat, dwell, and pressure conditions. "The wider the range of settings, the more suitable [the sealer] is for medical package manufacturing," says Johnson. The machines can be programmed to either shut off or alert operators to any faulty conditions.

Fuji Impulse's impulse bar sealers are guided by a microprocessor that allows operators to enter parameters recommended by the packaging material supplier. The sealers also feature alarms that activate if any parameter goes out of specification. "If the power surges, the machine locks and shuts down," explains Webb.

Med Pac impulse sealers from Packaging Aids Corp. (San Rafael, CA) feature digital readout of sealing parameters and alarm controls, which give operators immediate feedback if preset conditions fall out of range. Mark Goldman, COO, explains that the units can also output information to an external machine for further analysis.

O/K International (Sudbury, MA) has found a way to make validation even easier for packaging engineers. The Saxon 5 hot-air sealer is designed to operate at only one speed. "It is just one less thing that has to be calibrated," says Ann Marie Kellett, O/K's marketing manager. Packaging engineers only have to set the desired pressure and heat. The unit is also designed to go into reverse mode if any specifications aren't met—rather than accepting packages, the machine pushes the packages back out toward the operator.

To facilitate the monitoring of temperature on its impulse sealers, Packworld USA (Nazareth, PA) utilizes the heat-seal band as a temperature sensor, similar to an RTD probe. "With im-pulse sealers, the sealing cycle is over before you can correct the temperature—the band goes from room temperature to sealing temperature in milliseconds," explains Packworld's Frank Welles. "Using the heat-seal band as the sensor, we get instant and accurate feedback on the sealing conditions."

The Vivapac, an intermittent roll-fed poucher from Packaging Systems International (Berkeley, CA), is engineered for companies that want to step up from manual sealing of premade pouches but do not have the volume to justify highly automated equipment. Designed with calibratable controls, it enables users to adjust the following parameters on an external keypad: pouch length, draw roller speed, sealing time (for cross seal), duration of pause, and the temperature of cross and side seals. Packaging Systems' sales manager Alain Descoins explains that users can re-trieve these data and store them for fu-ture comparison purposes for assessing stability over time.

Other features available with many of today's heat sealers that facilitate validation are data loggers and date and code stampers. Parameter reporting is extremely important for validation, says Kent Hayward, product marketing manager for Alloyd Co. (DeKalb, IL). Alloyd's two-station shuttle tray sealer can be supplied with a data acquisition package. Four different packages are available, ranging from level I, which includes a digital temperature readout, a digital timer, and a line pressure gauge, up to level IV, which includes a touch screen, customized software, and a programmable logic controller that can log sealing parameters into a companion PC.

In addition to supplying a data acquisition package with its two-station shuttle heat sealers, Belco Packaging Systems (Monrovia, CA) can provide a bar code scanner that records codes printed on the package. "This feature enables complete traceability," says Tom Misik, national sales manager. "Users can determine when that particular batch was run and what parameters were used to seal the package on that particular day."


Many heat sealer suppliers are willing and able to help packaging engineers find a heat sealer that they can use and validate. But once the packager gets the machine into the plant, there is still a lot more work to do. Mike McLeod, senior packaging engineer for Merit Medical (South Jordan, UT), recently purchased an in-line band sealer from Doboy Packaging. Before the purchase, he wrote an investigational protocol to evaluate switching from a jaw sealer to the band sealer. The protocol involved evaluating how the equipment worked with a chosen packaging material by performing a range study to determine which parameters created an acceptable seal.

The BM 2020 Medical Blister Machine from Belco Packaging is designed for use with medical trays.


During the range study, McLeod found that he had to adjust the machine's heater bars and compression rollers to ensure that they would accommodate the material's thickness and that the package, when undergoing burst testing, reads well above the determined minimum burst allowance.

McLeod admits that the evaluation process is time-consuming but feels it is definitely worth it. Says McLeod: "The payoff is a process that is capable and a product that is sterile."

Packaging engineers are well advised to adopt such an attitude. Neither vague regulations nor a lack of a cookbook method should deter any engineer from developing an adequate system to validate heat sealers.

By keeping abreast of regulatory changes and new guidance documents and by asking suppliers and consultants for assistance, engineers should be able to create a system that works consistently and reliably.

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