Staying Up and Running with FFS
Form-fill-seal machines promote process efficiency, as production expands to vented pouches.
Motor motion control for seal stations and forming tools on the CFS Tiromat Powerpak NT thermoform-fill-seal machine swing the tools out for easy access during inspection and maintenance.
Deployment of servo technology and systems for line integration are promoting machine efficiency and cost reduction in form-fill-seal (FFS) and thermoform-fill-seal (TFFS) processes. Manufacturers are focusing on machine control, such as with industrial PC–based control systems, integration of primary packaging units and peripheral devices, and new machine features that minimize maintenance and changeovers.
FFS technology is also supporting the use of new package configurations as well the opportunity to use less-costly materials in pouch applications. For the in-line production of pouches and bags, 3-D packages made with thermoformed bottom webs are often favored over 2-D pouches as more efficient for medical device packaging.
“Thermoform-fill-seal becomes a better process for high-profile products because you are using less material. With a thermoformed bottom web, the formed cavity holds the product in place,” says John Merritt, director, medical business development, Alkar-RapidPak Inc. (Lodi, WI).
Adds Nick Fotis, director, packaging technology center, Cardinal Health (McGaw Park, IL): “Two-dimensional packaging often must be oversized in order to ensure there are no wrinkles when the package is sealed. The additional pouch or bag length that is required to do this often makes the product look overpackaged, or the packaging engineer look wasteful in the design.” (Fotis also serves on PMP News’s editorial advisory board.)
Industry is exploring alternatives for making vented pouches in-line. Cardinal Health is producing a hybrid pouch using Multivac’s Sterile Vent TFFS machine. A Tyvek patch is attached to the top web as it is unwound, after which the top web is brought down over the filled cavity for sealing, Fotis says.
“The hybrid package provides the same breathable functionality as a header bag. Depending on production volumes and speed, the Sterile Vent machine could replace the traditional header bag if volumes and costs warrant it,” he adds.
Cardinal uses several vent-type machines. Drapes are packaged with polyolefin top and bottom webs that are fusion sealed with a linear tear feature. For kit packaging, a peelable film top web—a high-density polyethylene coextrusion with a peelable layer—is mated with a polyolefin bottom web.
Fotis says the peelable films provide a material cost advantage over heat-seal-coated films. Their simpler chemistry has proven advantages as well. “Converters are making these coextrusions in a one-step process, with really good gauge control. Many of the heat-seal coatings have 10 or 20 different components in them, and often a chemical company will decide to discontinue a chemical. This requires us to do a complete revalidation. We have seen a significant decrease in revalidation requirements with the peelable films.”
“The peelable films have a heat-sealing window narrower than the heat-seal-coated materials, but all of our equipment is checked out to meet those tight temperature tolerances,” he adds.
JUSTIFYING VENTED BAGS
Cost benefits of the in-line production accrue through lower materials costs, the elimination of premade pouch inventory, and the capacity for in-line printing. The use of a porous vent in the top web enables material cost reductions that help offset the investment.
“By reducing the breathable area of the top web, we can move from a manually filled vented pouch to an automated packaging system. You can afford the capital investment and still return savings to the company,” says Fotis.
“If package sizes are changing frequently or batch sizes are small, it may not be cost justifiable to go with the Sterile Vent system, especially in the age of lean manufacturing. Making TFFS equipment and their accompanying printers capable of rapid changeover is key to their continuing viability for this application,” he says.
“We can change the flexo plate in a minute, but we need technology to support print color changes. We allow a half hour, but that is getting to be too long. The principle of single minute exchange of dies (SMED) has to carry over to printing systems,” Fotis adds.
Stefan Krakow, segment sales manager, technical packaging applications, CFS Tiromat (Wallau, Germany), says that the technology’s complexity has presented a barrier for adoption. Tiromat has offered a unit that integrates with an FFS machine for creating Tyvek-patched bags. “Requests for the concept have been limited. If you have one product in one pack size with large quantities, this becomes a good alternative to a package with a full Tyvek lid. This is a more-complex mechanical operation that affects the versatility of the machine. Different package sizes require different hole patterns and related tooling changes, and time-consuming mechanical changes and adjustments would eat up the savings you would get by using less-costly material,” he says.
In-line creation of flexible pouches with larger-sized vents or header strips, possibly using lower-cost porous materials, might be a more-promising solution. Work is under way today on this alternative. Strips would be fused together in a simpler process, according to several industry sources. “The machine would be set up without punching and patch feeding. Investment costs are lower, and the versatility of the machine is not affected as much,” says Krakow.
Servo control promotes faster machine speed, more seamless coordinated motion between line units, and precision in functions such as sealing and filling.
“We have been asked by medical device customers in particular to consider only servo controls. The operation of pneumatic circuits can increase the likelihood of product being exposed to airborne contamination,” says Michael White, general manager, Ossid (Rocky Mount, NC). White says that Ossid is in the process of developing servo motion on all machine axes, for cross cutting, trimming, web unwinding and rewinding, and scrap rewind.
Manufacturer and marketer of Mahaffy-Harder FFS units, Ossid focuses on custom projects such as nonstandard package shapes, custom trimming and loading systems, and line integration, says White.
Ossid configured a machine that clamps the webs above the clip line, for creating a rigid tray that sits flat and stable on a surface supported by flanges. Two moving tooling pieces sandwich the webs at the web line. “The film is shaped from the bottom, creating a tray with an upward impression. We have to reach up into the form with the sealing tool to support the rim for sealing,” White says.
An innovative product-loading and sealing configuration supported a medical device package that required a two-compartment rigid tray. The primary compartment packaged a gel solution. A second compartment captured the shaft of an applicator while protecting the bristles. Ten packages per cycle (five across, two in machine direction) are produced on a Mahaffy-Harder Model 805 machine, says White.
FFS units manufactured by Bossar USA Inc. (Sarasota, FL) use servos to support flexibility for changeovers and adjustments. Servomotors handle film advance, where the operator at a touch screen easily and quickly changes the film or pouch-advance distance, says Roger Stainton, president, Bossar USA and Duma Packaging.
“The primary machine processes are still mechanical. In some of our filling systems, we use servos for the ability to provide accurate filling. The check weigh provides feedback to the PLC to change the rotation of a filler through the servo drive and motor,” says Stainton.
“Closed-loop servo-based systems support faster speeds because mechanical movements can be accelerated or decelerated based on the relative position of the tooling, which is always known. I can start my index as soon as the tools have cleared,” says Alkar-RapidPak’s Merritt.
Alkar-RapidPak features a number of patented servo control functions in its thermoform-fill-seal machine. The latest extension of this servo technology is servo sealing, which uses a servo drive to apply and control pressure instead of pneumatically controlled air bladders for delivering sealing pressure. Servos are also employed in the RapidPak portfolio for indexing, plug assisting, and platen lifting.
“With the RP 55, we are offering the only TFFS machine with servo pressure control. Sealing pressure can be maintained at a higher level with more precision and reliability. One of the most important benefits of servo sealing, as opposed to pneumatic sealing, is that you don’t have to worry about plant air pressure issues,” says Merritt.
TARGETING MATERIAL COSTS
Servo sealing is of particular value for direct-seal papers, which require more-precise sealing pressure, says Merritt. Tighter sealing parameters are maintained for producing seals within the narrower minimum and maximum seal strength range required for medical device packaging.
Direct-seal papers, offered as an alternative structure to heat-seal-coated top webs or packages employing multiple-layer peelable films, represent significant cost savings. “Direct-seal papers are designed and produced for minimal fiber tear and can be used with fairly simple bottom-forming webs, such as nylon and polyethylene coextrusions. Papers from suppliers such as FlexMed and Arjo Wiggins employ paper furnish and chemistry that control the grain and optimize peel characteristics. Internal bond strength needs to be sufficient to prevent paper tearing. “In order to minimize fiber tear, the strength of the bottom-web seal cannot exceed the internal bond strength of the paper,” Merritt notes.
Merritt says that during opening, direct-seal papers are still more likely to have fiber tear than coated papers and peelable films, but for practical purposes they are fiber free. “The pressure precision we provide gives enhanced performance to these materials,” he says.
Merritt says that European and Asian markets have embraced direct-seal papers as a lower-cost alternative for many years. “The domestic market is convinced that any fiber tear is unacceptable.
However, there are many opportunities in flexible packaging applications that have not been explored, where minimal fiber lift may be acceptable. We at RapidPak are very excited about our ability to impact this particular segment,” he says.
Potential applications include syringes where the needle is sheathed to prevent contamination, surgical gloves packed in a protective inner envelope, and urinary catheters where long, narrow packaging minimizes fiber-lift potential.
Tiromat has focused on solutions that promote machine uptime and availability. “As a result of machines’ mechanical limits, and more specifically of the materials we need to run, we believe you cannot gain much increase in output from simply speeding up FFS machines. The cycles we are achieving now are pretty much the maximum with today’s packaging materials,” says Krakow.
“Output is promoted by higher machine availability, so a lot of our design work is aimed at reducing downtime factors,” says Krakow.
Tiromat’s newest FFS model, the Powerpak NT, addresses tool change and inspection functions. “Since showing the Powerpak NT at Pack Expo, we have released it for medical device applications, and we have orders shipping in October.” The machine features motorcontrolled motion for swinging out the seal station for visual inspection and tool changes. The forming tool is similarly deployed. “After a machine shut down, or before product start up, people usually require 10 to 15 minutes to check the seal head for damage and temperature. With the motion control solution, there is no need to cut the web and cut the power supply to take the tool out,” Krakow says.
Infrsync-Drive is an independent system used to drive the top web to prevent tension on the seal after sealing. Presently mechanically linked to the main transport chain, the drive will be redesigned with servo control, he says.
CFS CostFox software is optionally integrated into the Tiromat Powerpak and Compact FFS model control systems. The software delivers real-time reporting on factors such as synchronization between line units. Operators identify the status of upstream and downstream equipment, where time loss is occurring and adjust for bottle-necks. The operator receives feedback when working from the FSS control screen. “Waiting times are described, enabling the operator to know what times to improve in order to improve the overall machine efficiency,” says Krakow.
Multivac (Kansas City, MO) supports package line integration with an industrial PC (IPC) control solution, currently being rolled out on its entire line of FFS machines, vacuum-chamber systems, and tray-sealer units.
The Multivac IPC control system supports full-line motion control. Primary packaging machinery and peripheral devices can automatically adjust performance in response to line production status. The integrated control delivers easier machine reconfiguration and faster production speeds than is possible with PLC-based controllers. Line control is accomplished more easily and accurately than with a PLC-based system.
Multivac has said that the level of line component integration can vary, based on customer needs and application. Customers may elect full-line motion control or simply a “hand-shake” between two machines.
The control system manages peripherals such as bar code scanner devices for tracking coding data. The IPC software is written to the OMAC Pack ML standard. Devices such as robots, vision systems, and scanners incorporating the communication interfaces can communicate with Multivac units, without requiring custom software upgrades.