Form-Fill-Seal: Making the Switch
Can quick-change tooling ease and speed up your changeover?
The N2500 from Harpak/Hooper Engineering can be equipped with servo-driven form-station adjustment with the flip of a switch.
For many companies, horizontal form-fill-seal (FFS) equipment is a significant investment. Such equipment can be the most expensive machine on the packaging line. To make the most of that investment, companies often use that one machine for packaging a range of products. Changeover is therefore part of their routine. Merit Medical Systems (South Jordan, UT), for instance, is one such medical device manufacturer interested in quick changeover. (See the side bar on page 42 for more on Merit Medical’s story.)
Over the last few years, manufacturers of FFS equipment have worked to ease changeover. “We have to factor ease of changeover into the machine design,” says Marty Moscowitz, regional sales manager, medical consumer, and industrial division, Multivac Inc. (Kansas City, MO). In the past, “changeover was too long and too complicated. People have been looking for ways to make it more efficient.”
John Merritt, director, medical business development for ALKAR-RapidPak (Lodi, WI), explains the ease of changeover “often revolves around how easy it is to get tools in and out. Tools are often heavy and require a lot of muscle to remove and replace. This can result in health risks, such as strained backs, busted knuckles, etc. There is also a risk of damaging tools.”
To ease changeover, many FFS manufacturers now offer what they call “toolless changeover.” Quite simply, “Toolless changeovers are accomplished by a number of means, such as knurled knobs as opposed to nuts and bolts requiring a wrench,” explains Merritt. “Hoses are connected with integral quick-connect mechanisms, as opposed to clamps that are tightened with screwdrivers.”
Adds Moscowitz: “You can either turn a knob or flip a lever, or even just push a button.” To help Merit Medical with changeover and other tasks, Multivac designed a customized R530 thermoform-fill-seal solution for creating specialized medical kits.
Still, as easy as machinery manufacturers are making changeover, Donald S. Barcan, president and CEO of Donbar Industries Inc. (Long Valley, NJ), advises users to approach quick changeover “with a careful eye on all the issues, including validation and process control.”
Changeover ranges in complexity. The change may simply be to the packaging material, maintaining the same packaging footprint. Or, an entirely new package size or style may be needed. The amount of tooling changes depends on the degree of packaging change.
Tooling that can be changed includes forming dies, sealing platens, and cutting knives. Merritt adds that there are control issues that may need to be changed to accommodate different packages, such as “changing temperature, pressure, and index length.” Also, “there are peripheral issues associated with things like lot coders and in-line printers to changeover.”
Simple changes can often be made in seconds, while complex changes take longer. When changing materials, sealing parameters such as temperature and dwell-time may need to be changed. “When changing the material it would most likely be only a program change,” explains Vin Faherty, product manager, packaging, for Harpak/Hooper Engineering (Easton, MA). “This takes only seconds to change.”
Merritt offers the following range of changeover scenarios:
• When multiple product codes are being run on the same machine with the same packaging materials and configurations, changeover can be performed by replacing one printing plate with another and inputting a new lot code. (For more on this scenario, see the sidebar on page 44.)
• When package shape is being changed but the sealing pattern remains the same, the forming tools will have to be changed, probably requiring a change in forming parameters. Lot code and printing plate changes will also be likely.
• When package shape and sealing pattern are being changed, tools will have to be removed and replaced at both forming and sealing stations. Cutting systems may need to be replaced, and lot code and printing plate changes will also be likely.
Other changes involve adjusting forming depth, says Moscowitz. The depth of the forming die may only need to be adjusted, or for plug assist operations, the stroke of the plug may need to be shortened or lengthened.
In the case of RapidPak’s patented servo-driven plugs, the speed of plugs may need to be adjusted.
SHELVING THE TOOLBOX
Can all these changes now be made without tools? Most can, say FFS machine manufacturers. As Merritt and Moscowitz explain above, many tooling units have quick-change components and require just a bit of elbow grease to undo, change, or adjust.
Merritt says that in the past, changes in forming and sealing tools required that the tooling be removed and replaced, upward out through the top of the machine, which required that film be cut. “RapidPak is excited about its side extractable systems where tools are removed horizontally. It is easier to get to the tools, so there is less risk of injury as well as less damage to tools. Because these systems do not require that the film be cut and then rethreaded, start up after the tools have been changed is faster.”
Moscowitz says that one of the most important developments in the last three years is the addition of multiple tooling stations on one machine that can be changed with the push of a button. “On most of our machines, we can add two to three complete forming and sealing stations that can be called up using a human-machine interface,” he explains. “Each package format to be run on the machine is assigned a code number. Machine settings and parameters are stored as recipes that can be programmed by an authorized user.” Multivac’s onboard processor can store up to 50 recipes.
Hooper Engineering offers dual forming stations and dual seal stations, so changeover is just a flip of the switch, says Faherty. “As an option, the N2500 can be built to hold multiple sets of tooling in-line.” He says that Hooper is the only manufacturer to incorporate dividable tooling with different index lengths. “If the changeover involves a different index length, other firms sell another complete form set. The N2500 can also be equipped with servo-driven form station adjustment that alters the form station by the flip of a switch.”
Moscowitz says that storing multiple stations on one machine can add cost to the machine. “The loading area on these machines is longer, and therefore the machine is more expensive. In addition, die-lifting systems are needed for each forming die.”
The expense may be worth it, he says. “If firms are changing over more than once a day, they can justify this expense. It maximizes the efficiency of the machine. Also, larger tooling needed for bigger packages is harder for machine mechanics to handle,” so there are ergonomic benefits as well.
Future improvements will involve electronics. “The more changes that can be made with the programmable logic controller (PLC), the better. PLC changes are quick, they are verifiable, and history can be archived,” Moscowitz says. In addition, “more centralized control of peripherals can also be accomplished.”
Merritt adds that one of the major advantages of RapidPak’s servo-driven plugs, as opposed to pneumatic-driven plugs, is that they come totally under the control of the PLC.
Multivac is using more electronics, says Moscowitz. “We are using it to make adjustments, like for the depth of a die or the parameters of the longitudinal cutting systems.”
DON’T EVER CHANGE?
Barcan says that many companies that employ FFS machinery “do so because they want higher productivities and a lower per-unit cost for the package.” Higher volumes may justify a dedicated packaging line, thus obviating the need for routine changeover. “In my experience,” Barcan adds, “a daily production on FFS could be more than 100,000 packages, obviously dependent upon the devices being manufactured. Thus the goal is generally not to change out tooling.”
But there may be other reasons for foregoing changeover. Barcan points out that “validation of FFS is directly tied into forming tooling, loading, printing, sealing, and cutting. This process, when properly done, can take up to a week or more per tooling set. Once this activity is successfully completed, manufacturers would not want to ‘upset the applecart’ by making changes. This is also reinforced by the fact that FFS runs are generally three shifts for many weeks, if not months.”
In Barcan’s opinion, a partial if not complete validation would be required every time tooling is changed out. “Depending upon the actual situation, I think the cost of the revalidation could exceed the potential cost savings of ‘quick-change’ tooling. I’m not saying that quick change or ‘toolless’ tooling would not be an asset, but at what additional cost and at what compromise to process control and validation?”
But Merritt says that after changeover, “one merely has to confirm that the process is running within the acceptable parameters established by a prior formal validation/qualification process. Of course, all of this has to be documented,” he advises.