Championing Heat Sealers

Vendor support encompasses machine testing and material troubleshooting.

By David Vaczek, Senior Editor

Heat sealer manufacturers have devised more user-friendly machines that are easier to maintain and extend usable life. PLC controls make it easier to validate the sealing process, and monitor production of medical pouch and bag packaging.


But first and foremost, heat sealers must control temperature, pressure, and dwell time on a consistent basis. 

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Medical device packagers choose materials, validate the heat sealer and heat sealing process, and monitor heat sealer performance, following guidance in ISO 11607 Parts 1 and 2, and AAMI’s Technical Information Report 22.
 
In a heat sealer, they want a mechanically reliable machine with good parameter control. Device packagers will also look to heat-sealer manufacturers for support in a number of areas.
 
Heat-sealer vendors will often help in selecting the type of heat sealer best suited to an application. They may troubleshoot materials to ensure the selected packaging runs optimally on the sealers the customer owns or will buy. Vendors have offered new machine features to adapt sealing to challenging applications.
 
Vendors assist packagers in selecting a heat sealer, after the customer has presented the range of materials and package sizes.
 
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“Most of the time, the customer has already sourced a material with a supplier,” says Lynne Barton, product specialist, CeraTek, Sencorp Inc. (Hyannis, MA). “If not, we will provide contacts for appropriate material suppliers. We don’t necessarily recommend a particular material, but we can narrow down the choices to suit requirements, such as sterilization.”
 
“One of the first questions Sencorp asks of a new prospect or new application for an existing customer is, ‘What materials are you using?’” Barton adds. “The answer to this question helps us direct customers to the best solution for their application.”
 
 
 
PAC Machinery can customize sealing bar materials to match machine to material.
Medical device firms typically provide the vendor with sample pouches or materials for sealing. “We ask them to send us the samples and tell us their requirements,” says Ian O’Rourke, marketing manager, PAC Machinery (San Rafael, CA). “We then dial it in to see if our equipment can meet their requirements.”
 
“In addition to the sealing qualities required for the material, we take into account production demands,” O’Rourke adds. “A chamber, bar, or band sealer all might work, but the customer might need higher speed equipment, or more equipment.”
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Barton says some customers will send in the pouches along with product for sample-sealing at Sencorp. Alternately, “they can test the packaging at our facility, to ensure the process is truly represented,” she says.
 
Heat-sealer suppliers help find the sealing parameters for the material. “Companies in some cases will send us the materials to test at various sealing parameters,” says Jeff Quinto, general manager, Packworld USA Ltd. (Nazareth, PA). “We will test their materials on the equipment they are purchasing and report the parameters at which we obtained successful seals.”
 
“We provide settings that give the customer an idea of where to start,” Quinto adds. “Ultimately, it’s the customer’s responsibility to determine the sealing window as part of package validation. We will also recommend data from the pouch maker, which has extensive experience in converting its own materials.”
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The medical device manufacturer recalibrates the sealers and validates the sealer and sealing process at their production site. Packagers typically perform a systematic design of experiment (DOE) to define the limits of the sealing window and the optimal seal settings.
 
Vendors may offer step-by-step documentation to assist the customer with their IQ, OQ, and PQ validation.
 
Multivac (Kansas City, MO) offers validation services that include peel testing and oxygen analyzing, says Bill Williams, CPS product manager. “Customers either come to Kansas City to use our packaging lines and test equipment or they send package samples to us to test here,” he says.
 
ADRESSING MATERIALS
 
 
For assisting with validation, Packworld supplies sealers with an NIST-traceable certificate of calibration, with instructions on how they can duplicate the testing procedures, Quinto says.
 
O’Rourke notes that customers are verifying heat-seal windows and sealing parameters that PAC Machinery helps establish. “To us, validation means that the necessary temperature, pressure, and time are maintained every time the material goes through the sealing jaws, with an audit trail leading back to each and every seal in some cases,” he says.
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Packagers must choose the appropriate heat sealer technology. They sometimes require heat sealers that can accommodate multiple applications, putting a premium on sealer performance flexibility.
 
Packworld’s Quinto says, “Impulse sealers will seal every material that is sealable. All materials require a cool down period [to finish the seal].” Packworld machines are used to make devices such as IV bags, where a port is encapsulated in the side seam of the bag. The sealer element can be shaped to custom-fit the application. The sealing heat is applied for only a few seconds for protecting the device. The heat and cool cycle of impulse sealing ensures a secure seal in the poly material.
 
Quinto says Packworld impulse sealers can be set to simulate a constant heat sealer, such as to support higher speed production. Machines are programmed to a preheat setting, so the element stays at the set temperature even with the jaws open. The cooling cycle is programmed to the same temperature.
 
The constant heat mode of operation is enabled by Packworld’s TOSS technology that controls the element temperature by reading band resistance. “With resistance control, the actual temperature of the heating element is immune from external thermal influences A standard impulse sealer can’t maintain the constant heat, as the thermocouple reading will be influenced by ambient air when the jaw is opened,” Quinto says.

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“Different technologies present their own set of challenges, depending on the materials the customer is using,” says Sencorp’s Barton. “The most common material issue we help customers troubleshoot is using straight LDPE on a constant heat sealer,” she adds.
 
Sencorp has devised a solution for companies sealing monolayer LDPE bags on constant heat sealers. “We developed this to help a customer who had purchased a constant heat sealer for a myriad of different pouches and materials,” Barton says. “Although Sencorp manufactures both impulse and constant heat sealers, we recommend the use of constant heat sealers for medical packaging applications where possible. We find that they are easier to calibrate and validate, and the maintenance costs are significantly lower.”
 
“Some of our customers sealing straight LDPE on constant heat sealers were getting visual imperfections in the seal due to the nature of the material and the way it cools as it pulls away from the heated die,” she says. “These were not seal failures, but they often did not pass a visual inspection.”
 
Visual anomalies in the seal normally occur when a pouch is removed from a Teflon-coated die when the seal is still warm and fluid. Sencorp’s solution integrates a Teflon cloth apparatus that eases pouch extraction from the machine while allowing the seal to cool.
 
“The seal has enough time to cool, even if the cloth is pulled away a split second after the pouch is removed,” Barton says. “We have found this eliminates the problem 99% of the time.”
 
O’Rourke says getting the maximum performance out of materials is part of the discovery process at PAC Machinery.


Remedies can include Teflon coating on the sealing element, for materials that melt at a lower temperature than Teflon, or seal bar cooling features. “For certain high temperature materials, we mask the sealing bar. You are creating a contained channel so the material doesn’t elongate during sealing,” he says.
 

Emplex Bag Sealing Solutions (Toronto), a division of PlexPack, added features on its continuous band sealers for improving seal performance and appearance.
 

“Our standard machines seal poly and coated Tyvek bags easily,” says John Lewitt, vice president of sales. “As customers have moved to uncoated Tyvek to reduce their costs, we started having problems with the seals.”
 
 
Emplex supplies an optional rubberized pressure roller that applies pressure to the seal once it leaves the heating section. “This allows us to seal through the inconsistencies in the materials and make a better, peelable seal.”
 
For foil bag production, Emplex uses a stainless-steel pressure roller that applies pressure to the seal after heating. “We don’t have problems achieving a strong seal, but some foil bags will wrinkle when sealed on a continuous heat sealer. [The roller] dramatically improves the appearance on these bags,” Lewitt says.
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