Pouch Sealers Deliver Verifiable Quality

CMD Corp. offers real-time process analysis and control in sealers for the medical device packaging market.
By David Vaczek, Senior Editor
CMD Corporation (www.cmd-corp.com) has introduced pouch converting machines with enhanced process management tools for medical applications. The machines feature Intelligent Sealing Technology (IST) from CMD Corp.’s PDI division. The new technology represents CMD’s commitment to “Process Driven Innovation” in the design and manufacture of PDI-branded pouch converting equipment.
PDI’s IST has been used since 2008 in intermittent-motion production for medical segments such as medical and dental packaging, producing pouches from various laminates, as well as a combination of laminated film sealed to paper or Tyvek. CMD has now implemented the technology into their traditional cross and longitudinal sealers, used to produce Tyvek header bags.
“It became apparent that the same level of technology would be well-received in other areas of the medical packaging market for addressing more demanding pouch and bag applications and an increased need for supporting production data,” says Scott Fuller, Intermittent Product Line Manager, CMD Corp.
“We looked at where we could take costs out without affecting the performance and reliability. [With IST] we can provide customers with the assurance of real-time process management at a cost that will still allow the converter [and OEMs manufacturing pouches from rollstock] to realize the benefit to the bottom line,” Fuller adds.
In most legacy machines on the market, production data is often collected through manual means or secondary systems used to help automate data collection, Fuller says.
The PDI Medical Combination Pouch Machine flexibly produces chevron pouches and header bags, with Intelligent Sealing Technology for seal parameter control.
IST controls the entire sealing process, as temperature, pressure, and dwell is measured for each strike of the sealer. The machine self-corrects for sensed process deviations as seal data is automatically fed back to the controller. Data for each pouch produced is stored in the PLC.
The automated process management yields verifiable product quality—a high level of confidence in the quality of the product. Converters can reduce the time and cost associated with extensive sampling and process development protocols for ensuring packages meet quality standards, Fuller says.
With the IST technology, variability in the sealing process is minimized with a “zero lost motion” design. The anvil is fixed rather than floating on springs or cylinders, so it is immovable when the platen drives the pressure into the surface. The platen is driven by a servo-controlled, high-precision, rotary-linear actuator without the use of springs or cylinders to allow for “over-penetration.”
“Platens, even if servo-actuated, are sometimes provided with some means of over-penetration. This becomes a source of lost motion. Cylinders driven by hydraulics or pneumatics inherently possess a level of lost motion through the compressibility of the cylinder air or fluid,” Fuller explains.
Accurately controlling and measuring dwell time is a particular challenge in traditional premade pouch-making machines as dwell can be as low as
70 ms at top speeds. In heat sealers used for closing filled pouches by comparison, the dwell can run into multiple seconds. IST measures actual time in contact with the sealing surface at top speed.
“People had the tendency to focus primarily on temperature in the past, but substrates such as the peelable films used today, which are engineered to fail within a specific tensile range, have tighter operating windows for dwell and force. You make a small change and you can see the results it when doing your testing,” Fuller says.
In the IST servo-actuated control of dwell, the main PLC accounts for the mechanical position as well as the force of the sealing platen. The force is thus identified within a position window.
“Older machines with hydraulic or pneumatic components and controls are driving just to a force. This creates more sealing variability. Some companies will develop complex regression equations to characterize the system’s behavior and account for factors such as rubber degradation and mechanical binding or sluggish cylinders. As the equipment wears, the numbers become less reliable and you have to tweak as you go,” Fuller says.
“If you are driving 2 mm deeper because the rubber sealing surface has degraded, you have a longer movement. Or you could be 2 mm above the surface of the web because someone left an Allen wrench in there. We are driving the seal tool to a mechanical position and a force for complete position control with ‘zero lost motion,’ ” he adds.
IST controls the platen velocity, sensing and measuring the moment the platen makes contact with the substrate for consistent contact.
“We slow down the velocity just before it hits, so we don’t get bounce. We maximize the dwell cycle by eliminating the settle-time associated with other sealing systems.”
The market will eventually move to the newer machine technology, but only as significant hurdles for adoption are cleared. “Customers want to know what it will cost to get the machine up and running. As with any newer machinery, it will require significant validation work to bring this new technology on-line. Companies are often reluctant to convert to new equipment one machine at a time because customers may demand for pouches to be converted using the more reliable process and a single machine may not handle that demand. This makes for validation costs that are much more challenging,” Fuller says.
“The vast majority of machinery for medical device packaging is 20 to 30 years old. As market demand for new technology creeps up, converters will have to ask, ‘What is the technology that will put me in the best position for the long term. Converters don’t want to incur the cost of replacing the machine again for at least 20 to 25 years,’ ” says Edward J. Verkuilen, CMD regional sales manager.
“PDI has a proven track record when it comes to the longevity of our machines. We have machines in the field making Chevron pouches with medical device manufacturers that are upwards of 30 years old. People are replacing the electronic controls in these because mechanically they are so reliable,” Verkuilen adds. 
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