Easing Heat-Sealer Validation with Controllers
Suppliers are cutting back on the bells and whistles and instead focusing on validation-friendly features.
|Packworld USA relies on the new RES-400 series controller for handling all heat-sealer functions.|
If you are shopping for a new heat sealer, you've probably noticed plenty of new devices that promise to improve your sealing process. You may also have noticed fewer of what one industry representative calls "trade show devices"— gee-whiz machines that draw a crowd at shows but don't deliver real benefits when installed on the factory floor.
Suppliers say that engineers typically steer clear of such flashy machines and instead look for "validatable" equipment—equipment that precisely controls sealing speed, pressure, and temperature parameters. Once these parameters have been established, packagers set the tolerances for the controllers that constantly check them.
Suppliers are equipping their machines with dependable controllers that are easy to use and calibrate. Through the use of such controllers, engineers can determine "that bags coming out of the sealer have been sealed within these tolerances and that they won't be liable" for faulty seals, says John Lewitt, vice president of sales at Emplex Systems Inc. (Toronto). "That's what validation is all about—knowing the right parameters have been used to close a bag or tray."
Today's heat-seal equipment eases validation in two ways. First, simplified control systems reduce setup time and enable engineers to be more precise when setting parameters. Secondly, many standard systems include audio and visual alarms for each parameter.
It may seem basic, but to maintain control, you must have easy access to the controllers. To afford engineers this opportunity, suppliers have made the controllers on their equipment easy to set, read, adjust, and monitor.
In some cases, location is everything. For instance, Emplex's MPS 6300 series, which includes tabletop, stand-alone, and conveyorized models, features temperature, pressure, and tachometer controls on the front panel. Operators do not need to move the sealer for adjustments or monitoring.
Since digits can be read more quickly and easily than dials, several heat-sealer manufacturers incorporate digital controllers in their systems. With digital units, operators "don't have to guess at [the value] on an analog gauge," notes Thomas Misik, vice president of sales and marketing for Belco Packaging Systems Inc. (Monrovia, CA). To keep operators from guessing, Packaging Aids Corp. (San Rafael, CA) has designed all of its floor-standing and tabletop medical heat sealers to be fully digitally controlled.
Digital technology is more precise than previously used analog technology, says Charles Trillich, president of Packworld USA Ltd. (Nazareth, PA). All Packworld USA equipment now employs controllers from its sister company, Toss Machine Components Inc. (Nazareth, PA). The new digital RES-400 series controllers feature digital displays and touch-pad controls for handling all machine functions without a supplemental programmable logic controller (PLC). Temperature control is repeatable to within 3ºC, and the controllers can rapidly increase the temperature of the heat-seal band.
Suppliers are also making controller calibration easier. Many sealers include ports for the insertion of pressure and temperature gauges. One such machine is Belco's new tabletop tray sealer, a single-station, 10 x 10-in. tray sealer that is roughly one-fifth the size of a dual-station floor model. With its external calibration ports, "you don't have to open up the guts of the control," says Kevin Debbs, a process engineer for Osteotech Inc. (Eatontown, NJ), which uses the sealer. "This makes it a lot easier to do calibrations and validations."
Ann Marie Kellett, marketing manager for O/K International (Marlborough, MA), explains that the OK Supersealer features plug-in thermocouple connectors and a seal pressure interface in the back of the machine to ease calibration.
SAFETY IN NUMBERS?
While most, if not all, sealers use some sort of control system, not all suppliers agree on how many controllers are necessary. Emplex, as part of its standard validation package, offers its machines with a controller for each of the three sealing parameters.
Belco, however, whose unit includes a PLC, eliminated a temperature controller on one machine. "The PLC controls all packaging parameters—time, temperature, and pressure—which makes the machine a simpler piece of equipment," Misik says.
While most machines now have separate controllers, Russ Perrone, national sales and marketing manager for Packaging Aids, sees heat-sealer manufacturers moving toward full PLC control. Besides simplifying the equipment, PLC control should offer other advantages over separate controls. "Three independent controls take up more space" than a PLC, Perrone notes. "They also require more wiring and more lines to hook up. So with a PLC, you're saving materials, you're saving labor, and you may be saving on the cost of the equipment."
Zed Industries Inc. (Vandalia, OH) offers full PLC control on its line of heat sealers. The PLCs save operating parameters from specific jobs, and users can easily "jump from job to job without consulting a handbook," explains vice president Peter Zelnick.
PLCs are part of the trend toward increased automation. Automation promises increased sealing throughput and efficiency as well as reduced manpower and costs, says Todd Hiser, general manager of Clamco Corp. (Cleveland). (For more on automation, see sidebar below.)
To prevent flawed seals from being made, manufacturers are equipping heat sealers with alarms and "no-feed" systems. For example, a new stainless-steel rotary pouch sealer from Van der Stahl Scientific Inc. (Wrightwood, CA) has a microprocessor that monitors sealing parameters. If one of the variables doesn't fall within the proper tolerance limits, an error message appears on the device's screen. "But more important, the machine won't allow a person to feed material," says Charles Webb, director of Van der Stahl's sterile packaging division. "The no-feed system makes it pretty difficult to put out a compromised product."
When the alarm sounds, machines from Packaging Aids lock the control panel. "This means that the operator can't just decide to go on with the process anyway," notes Perrone. The only person who can clear the alarm is a supervisor with a key to the box. This increases the likelihood that the supervisor will inspect the equipment to determine the reason for the alarm.
Packworld USA has designed a similar safeguard. If any individual sealing cycle fails to fall within the tolerance limits that are keyed into its controllers, the machine locks and alarms the opertor. System faults also trigger an alarm.
TOO MUCH INFORMATION?
A few years ago, engineers said that data acquisition features added to sealers could help them track conditions and trace the roots of any problems. To this end, Van der Stahl is introducing what it calls a "seal check" system. Featuring an integrated printer, the system prints each day's force, speed, and temperature settings on the sealed pouch. "If someone says there's a problem with a pouch, you can look at the seal check and see exactly what parameters were used that day," Webb says.
Other sealing systems gather time, temperature, and pressure data on every seal. Made by Alloyd Company, Inc. (DeKalb, IL), and others, these systems use sensors to gather the data, which are then stored in a computer.
Packworld USA offers an optional data logger that will produce on demand a hard-copy profile of a process's sealing time and temperature. "A graphic display of the sealing cycle reassures customers and regulatory authorities," says Joe Smith, sales and marketing manager.
Zelnick says that the onboard data printers offered as options with his firm's heat sealers have been particularly well received. "These printers, which take data downloaded from a PLC, provide records of product name, date, lot, and operational parameters. Firms can store these printouts with their production samples as records of consistency."
So far, though, data acquisition systems haven't been a hit among medical packagers, according to Lewitt of Emplex. Data acquisition "hasn't taken off the way we thought it would," he says. "I guess it's overkill for some people."
Make that everybody, Perrone says. "It's more fluff than something that's required for quality machine operation. If your machine is alarmed and calibrated, it will tell you when you have a bad seal. Memorializing the data does nothing more than take up disk space."
Webb says that heat-sealer manufacturers are now less interested in wowing customers with clever but superfluous technology. "For a while, manufacturers raced to see who could put the most bells and whistles on their machines. Now manufacturers are streamlining down to the essentials of what makes an easy-to-validate machine."
William Leventon, Contributing Editor