Medical-Grade Heat Sealers: Electronics Seal the Deal

Whether for validation, quality control, or just a more precise seal, heat-sealing machines rely on electronics for optimum performance.

by Erik Swain, Senior Editor

Within the past five years, heat-sealing equipment for medical device packaging has entered the electronics age. The machines used to rely on analog time, pressure, and temperature controllers to ensure that seals were made correctly. But by the mid-1990s, equipment users began to fear that the units did not control the sealing parameters precisely enough, and therefore could not be counted on to provide each package with the same quality of seal every time.

Electronics, however, do allow such precision and consistency. Heat-sealer manufacturers have responded to industry's concerns by offering sealers that set time, pressure, and temperature electronically, ensuring a successful, repeatable seal.

But that move does not mark the end of electronic innovation. Many newer machines are now supplied with data collection and monitoring features that can be used in quality control and validation. Whether these become as widespread as electronic time, pressure, and temperature control remains to be seen.

"The machines are constantly in flux," says Ann Marie Kellett, marketing manager, O/K International Corp. (Marlborough, MA). "They are being made better by the customers' demands, whether they be to provide data collection and validation or to cut costs. The machines also have to be more versatile because they have to run a lot more different materials and products than before."


Electronic control of the heat seal continues to improve. For instance, Charles Trillich, president of both Pack World USA Ltd., which makes heat sealers, and TOSS Machine Components Inc. (both in Nazareth, PA), which makes electronic components for heat sealers, says that the newest units control sealing temperature better because they make adjustments better. "The heat-seal process takes place so rapidly that it had been almost impossible to control temperature," Trillich says. "During the course of the day, the equipment heats up, so the temperature at the end of the day is different from the temperature at the beginning of the day. But now we can very precisely control the temperature of the heat seal in a way that was never before possible."

TOSS describes the control process this way: "The controller continually monitors the actual temperature of the heat-seal element by measuring the changes in [electrical] resistance of the heat-seal element as its temperature changes. The determined temperature is displayed and compared with the preset temperature target. The primary voltage of the power transformer is then automatically adjusted to achieve the desired temperature level. This closed-loop system constantly monitors and instantly corrects the temperature, so that the actual temperature always equals the preset temperature. The smallest thermal change in the heat-seal element is immediately recognized and instantly corrected with precision."

As electronics have allowed increased accuracy and repeatability of the seals, they have also had an impact on other components of the machine. "More stringent requirements for sealing technology" have created a demand for "more precise sealing surfaces" and better gaskets, says Bob Robbins, president of gasket supplier Inter-Tech Supplies Inc. (Allentown, PA). "They used to be cut by hand, but now they absolutely have to be done with molded products. There is no room for human error, and you can only cut by hand so carefully."


There are two control options available for heat sealers. Engineers can choose from machines that are run by programmable logic controllers (PLCs) or personal computers (PCs). Either kind of system can come with or without data acquisition features.

"There are two directions [heat-sealer users can go]," says Kent Hevenor, product manager—laboratory machinery at Sencorp Systems Inc. (Hyannis, MA), a division of DT Industries Plastics Group, which offers heat sealers in varying degrees of electronic sophistication. "There is the full-blown PLC that plugs into a computer and offers temperature, pressure, time alarms, and 100% traceability. Or there is one step less, which is putting in individual controllers for temperature, pressure, and time. They are not tied to a PLC, but they can alarm and lock the machine out. You don't get the ability to download the information to a computer."

Belco's mechanical product ejector gently removes packages and protects the finished seals from damage after the seal cycle is completed. Photo Courtesy of Belco Packaging Systems.

The optional bar code scanner inputs both sealer and package specifications into the data acquisition database. Photo Courtesy of Belco Packaging Systems.

There are clear advantages to using a heat sealer that can communicate with a PC, says Thomas A. Misik, vice president of sales and marketing of Belco Packaging Systems Inc. (Monrovia, CA). These include traceability and the ability to verify and document sealing alarms. "You can log on to a computer system and show the internal regulatory people that an event happened and what the remedy was," he says. "Then you can notify the customer or device manufacturer that the product did not get out the door."

However, device makers need to assess whether their needs for data collection and validation justify the cost of a more sophisticated system. "Not everyone needs that type of equipment," says Misik. "The customers who do need it are looking for data acquisition, or for absolute process control or validation, or to conform to ISO standards, or are people who have been involved with a recall and their corporation has dictated complete traceability."


Medical-grade heat sealers can also rely on PCs for parameter setup, which facilitates data collection. "Available today as an option, one PC can set up sealing parameters on as many as 10 heat sealers and collect all cycle data to a spreadsheet," says Kent Hayward, marketing manager for Alloyd Company, Inc. (DeKalb, IL). "Once in memory and connected to a network, stored or real-time data could be accessed from any place in the world over the World Wide Web. Say you had a quality assurance director in Connecticut who wanted to know about a machine operating in California. He or she could read the performance data on-line from the Connecticut office."

Process monitoring with out-of-range shutdown and data collection capabilities saves money in the long run, Hayward says, because without it "companies spend more money and time testing sealed trays for leak conditions."

Belco's medical tray sealer offers integrated network-compatible data acquisition software. Photo Courtesy of Belco Packaging Systems.

The collected data serve two major purposes—proving that the seal was repeatedly applied correctly and showing what went wrong if there is a problem. "It can tell you why the equipment is not as efficient as it could be," says William C. Cairns, new market development manager for SIG Pack Inc. (Raleigh, NC). Examples of problems that machines encounter, he says, include variation in product dimensions, changes in temperature, and the absence of packaging materials.

Other conditions that can be identified and prevented through monitoring, Misik says, include inadequate pressure, incorrect parameters for the relevant tools, and double cycles, in which the sealing process is performed twice on the same package.


How popular electronic data collection and monitoring becomes will likely depend on the stance of FDA, suppliers say. If the agency, through regulation or encouragement, starts expecting second-by-second, degree-by-degree data in validation, then the bulk of device makers are likely to want the technology. For now, some in the industry are waiting to see what FDA will do before investing in such features. At the moment, it appears that the agency expects heat sealers to be validated, but has not given precise instructions how to do so.

"The need to confirm that you have a hermetic seal is not waning," says Paul Irvine, president of Emplex Systems Inc. (Toronto). "The thought was that FDA was going to regulate it somehow. I don't believe that has gone away."

The screen displays temperature control capability at 1/100 of a degree. Photo Courtesy of Belco Packaging Systems.

But, notes Hevenor of Sencorp, "Given the alternatives, people are not going to want to start gathering [data] if they are not going to be able to do something with it."


The addition of electronic controllers has vastly improved heat-sealer performance, but incremental advancements still remain to be made in order to completely meet end-users' needs.

Increasing customization is a trend. For example, users who want to print lot codes from their sealers need enhanced electronics. So do those who want to use a bar code to set up the machine automatically for the parameters of a particular package or product. The engineering staffs of several suppliers are working to determine which nonproprietary custom features are appropriate to add to standard machines.

However, device packagers are increasingly under pressure to contain costs, so they are constantly searching for ways to economize. For example, Kellett says one of O/K's equipment features that customers like is its calibration ease—they can calibrate the equipment themselves without having to pay an outside technician.

"The technology has gained 10 to 15 years in the last five years," says Hevenor. "Suppliers have made huge strides to meet industry demands. Now the question is, is there a more cost-effective and efficient way of doing the same thing? We have to revisit less expensive ways to accomplish the same thing without compromising quality."

Opening Photo Courtesy of Alloyd Company, Inc.

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