Enabling Compliant Seals
Published: May 17th, 2011
Validation should ensure consistent seal strength and package integrity.
Process controls and user-friendly features on heat sealers go a long way in supporting effective bag sealing for terminally sterilized medical devices. Yet ensuring consistent seals can be fraught with challenges. Defective and cosmetically marred seals may put product at risk for contamination and increase manufacturers’ costs.
ISO 11607 requires the heat seal process to be under total control and validated. The standard’s accompanying AAMI guidance, Technical Information Report (TIR) 22, names five areas where failures in process control can lead to defects: device, packaging system, people, process, and environment.
In a recent Pharmaceutical & Medical Packaging News webinar on “Validating Rotary Medical Sealers, Improving Process Control,” Bosch Packaging Technology (www.boschpackaging.com) reviewed sealer validation and variables that can compromise package integrity.
“Our responsibility is to provide a machine designed to meet the ANSI/AAMI/ISO 11607-2:2006 standard and meet all industry and regulatory requirements,” said Ray Johnson, product manager-bag closing, Bosch Packaging Technology.
“The device maker or packager is responsible for producing a safe product. (This entails) complying with ISO 11607 and eliminating or reducing risk surrounding the medical device sealing process,” Johnson added.
PROBLEMS WITH PROCESS
Webinar attendees named “people” and “process” as the leading defect-causing obstacles, followed by “packaging systems” as another area of concern, in the webinar’s polling. (For our Webcast Wrap-Up, see page 24.)
|In Alloyd Brands' Aergo medical tray sealers, platens are casted with the heater elements inside and the platen mass is optimized to eliminate cold spots for better temperature stability and uniformity.|
Validation can include any component of the sealing process that relates to consistent performance, the speakers noted. ISO 11607 outlines IQ, and OQ and PQ for establishing the sealing values, and worst case testing methods.
“I speak with medical device people daily whose interpretation of ISO 11607-2 often varies significantly, but the common goal is total process control and reducing the occurrence of failure,” said Mark Larson, sales engineer-bag closing, Bosch.
“You need to map your process to determine worst-case conditions. This helps you understand the critical parameters and process variables for defining your project scope and developing your design qualification. Ideally, this is done before you do the user requirement specification,” Larson said.
The Bosch B-550 M and CBS DM medical-grade continuous band sealers include a Watlow digital temperature controller, with a temperature verification port for testing the controller’s readings against a secondary temperature sensing device. A PLC monitors the high and low parameter settings established in the OQ. Any deviation causes the sealer to stop or reverse direction.
PACKAGE, AND PEOPLE
Bosch has most recently added a 500-position encoder on the B-550 M that provides more precision in the belt speed monitoring. The encoder takes 500 counts per revolution of the belt wheel. “Speed on a rotary sealer is critical, as it relates to the amount of time it takes the package to pass through the heating and cooling bars,” Johnson said.
Manufacturers of all types of sealers—bar, band, and impulse—offer features for minimizing manual operator involvement.
“Frequently, personnel turnover is one of the biggest obstacles; machine features that limit the influence of the operator reduce the possibility of failure,” said Johnson.
Bosch rotary sealers feature bag top guides as a physical reference in positioning the pouch and setting the seal location. Sensors can be added for ensuring the top of the pouch is aligned for sealing and that product is properly nested before entering the sealer.
Companies having issues with the “packaging system” may be using unsuitable bag sizes. “Generally what we often see is backward design. The company starts with the case, then designs the carton, and then designs a pouch to fit in the carton,” Johnson says.
“The pouch has to be properly sized for the device and the rotary sealing process. When feeding a short package with a limited amount of head space above the product into a rotary sealer, you can get bunching, which leads to a defective seal.”
Bosch, and Plexpack, the manufacturer of Emplex Bag Sealing Solutions equipment (www emplex.com), feature band break alarms signaling to the operator the Teflon sealing band needs changing. On Emplex continuous band sealers, product shelves and bag top guides further support bag sealing performance, says John Lewitt, vice president of sales, Plexpack.
“Sometimes customers don’t use the machines for their intended purpose, and in some cases don’t even realize they are misusing the machine. It is worthwhile to invest in operators that take possession of the process,” Lewitt says.
“A continuous sealer should only operate when it’s functioning within its validated parameters. As a standard feature on our machines, if the machine is in alarm mode the operator cannot feed the bag into the sealer,” he adds.
At PackExpo, Plexpack launched an updated MPS7000 series with new features including a see-through Lexan cover for visual seal station monitoring. For plug-and-play add-on of a conveyor to the MPS7100 stand alone unit, the machine is prewired for easy addition to the control box of a preprogrammed conveyor speed controller.
Launching later this year, MPS7300 and 7700 validatable sealers will run 60% faster with double the heating and cooling capacity of Emplex’s validatable MPS6300 and 6700 machines.
“There are some difficult-to-seal bags on the market that can only be sealed in the 10 to 20 foot-per-minute range. A single operator can generally load the machine at a greater rate than that.
“These units are basically our standard validatable units, doubled, with two 5-in. heater bars and two 5-in. cooling bars, for a 20-in. long section. And you can add a second operator for increased production,” Lewitt says.
CONTROLS FOR TRAY SEALERS
Tray sealers from Alloyd Brands (www.alloyd.com), a business unit of Tegrant Corp., feature proprietary technologies that address sealing consistency and ease of operator use, with advanced systems for plant level control.
“As a leader in tray sealer machinery and heat seal tool manufacturing, we have created though our experience, and with testing partners and vendors, collaborative expertise in heat sealing for medical packaging requirements,” says Vishal Malhotra, vp marketing and business development, Alloyd Brands.
The Alloyd Aergo medical tray sealer line is designed for safety and ergonomics following OSHA ergonomics guidelines. The height of the work surface is optimized for operators reaching into the machine. Featuring category 3 safety circuits, machines have recently been upgraded for NFPA 79 (National Fire Protection Association) compliance.
Alloyd Brands has added technology for enhancing sealer process control and quality. “The sealing process is usually the most problematic for customers due to the wide array of parameters, including but not limited to material and tooling variations,” Malhotra says.
Platens are casted with the heater elements inside, and the platen mass is optimized to eliminate cold spots and for better temperature stability and uniformity. The Aergo 2 tray sealers were developed with an ATEX system for automatically loading and unloading the heat plate. Customers desiring the ATEX feature receive the benefit of holding the heater tooling tighter against the platen and achieve better heat transfer and more uniform temperatures.
Alloyd Brand’s PLC-equipped medical trays use a loop module to control the temperature through the HMI, which in turn can be remotely configured, programmed, and monitored through a plant-level DeviceNet network.
Alloyd has increased the wattage of the heaters to achieve faster recovery time and effective control on temperature loss. “The faster recovery time ensures that the sealing process is repeatable at customer-specified run-rates. Moreover, the wattage increase combined with the use of resistance-matched elements in the platen ensures that there is temperature consistency (with a ±5° F variation from setpoint across the surface), which in turn accounts for higher sealing accuracy,” Malhotra says.
For controlling pressure on the Aergo sealers, an electronic pressure regulator controls a proportional valve. The regulator allows users to enter pressure set points and alarm values via the HMI. The operator also receives feedback from the electronic regulator that is used to monitor the actual process pressure and generate alarms if the process pressure is out of limits.
In an RFID identification system on the Aergo 2 PLC line, tools are tagged with RFID chips that automatically load the time, pressure, and temperature parameters for each set of tooling as it is placed into the machine. The RFID system speeds changeovers, eliminates errors, and enhances consistency, in taking the guess work out of the set up for multiple sets of tooling.
Certified gauges, validation ports, and an Ethernet IP Module support process control and feedback.