Commonly called "flexos", this family of machines is the workhorse of the corrugated box industry. It is estimated these machines make more than 70% of the boxes produced in the United States. A sheet is fed into one end and emerges from the other end as a knocked-down box, part of a counted bundle and ready to be shipped to the customer. On its way through the machine, the sheet is squared, vacuumed, printed, scored, slotted, possibly diecut, glued, folded, squared again, counted and tied. The fastest machines accomplish this at a rate of 300 boxes per minute, usually with a crew of two men.

Increasingly Versatile The technology of flexos has improved over the years. If a carton cannot be made on a flexo in one pass, then it most likely must be made elsewhere in two passes at a higher cost. Therefore, machinery manufacturers have been stretching the envelope that encloses work that can be made on the flexo. Naturally, increased capability comes at an increased price, but if a particular option makes sense to a company, it may pay to add the feature.

Improvements in printing have been in increasing demand. The shipping carton as a billboard has been accepted as a marketing concept. The warehouse-type stores have been insisting upon graphics that can sell the products off the racks. Consequently, three- and four-color flexos have become quite common. The machines are made in a modular design so that color stations can be added, shared with another machine and even shuffled to change the sequence of the anilox rolls.

Printing Printing is being done with ever-finer screen counts. Thin plate technology is increasingly used to reduce the effects of stretch and compression forces inherent in flexible printing plates. Anilox rolls are made with different ink-carrying characteristics, and the sequential requirements may differ from job to job. That is why print stations are made to be shuffled, as noted previously; the alternative is to remove and replace the anilox rolls, which is especially difficult for bottom-printing machines.

The methods for metering the ink on the anilox rolls have changed from the use of a wiper roll or single doctor blade to the chambered doctor blade. This device uses two doctor blades to form a chamber into which ink is pumped and kept under pressure, assuring contact with the anilox. It also reduces dust contamination and evaporation of the solvents.

Diecutting Rotary diecutting has been done on even the earliest flexos, but the basic machine does not include a modular diecutting section. Those plants that have an occasional handhole job mount pairs of cutting heads with soft anvils to enable making the box in one pass. Plants with considerable diecutting needs may incorporate an integral or rollout full-width rotary diecutter.

Numerical Control There are many adjustments to be made when converting a flexo from one box size to another. If all the adjustments must be made manually, it could take as long as 25 minutes. Plants with a small-order mix of work find themselves spending more time setting up than running. To overcome this situation, machine manufacturers have motorized many of the adjustments that must be made and have made them operable by keyboard entry. They even went one step further and provided for computer storage and retrieval of the dimensions. While some machine designs have numerical controls on almost all axes that can be adjusted, others have options that may be selected by the buyer. The time for setting up the RSC has been reduced to just a few minutes.

Extreme Sizes Machine manufacturers have been stretching the envelope to cover both larger and smaller boxes. Large boxes require long shafts that must be made massively to avoid deflection. Large panels are difficult to fold, and resistance affects the running speed. Also, it should be noted that large boxes present a handling problem; they emerge from the corrugator with the print surface down. Using a bottom printer avoids the need for inverting the sheets. Large machines are technologically effective and justified, however, because they cost less to run than a slat-fed slotter with a semi-automatic folding machine.

Very small boxes are not only lightweight but springy. This makes them difficult to collect, pile and tie, especially at high speeds. Some mini flexos need a third man on the crew just to watch for and clear jams. The other major problem is one of blank size. A corrugator might cut sheets down to a 22-in. length, yet the box might be smaller than that. In which case, the blanks might have to be cut down at an operation prior to the flexo. There have been some flexos made with a drop-off mechanism, which cuts a double-up length in half for subsequent feeding.

Narrow width blanks might encounter a minimum distance between nip points on their way through the flexo. The sheet must be held firmly at all times if registration of printing and slotting is to be maintained. If the printing plate is to be considered a nip point, then the location of the printing is key. The proximity of the nip points is related to the diameters of the print cylinders and slotting heads, so a smaller minimum width creates a smaller maximum width. There are several machines that kick two sheets for each revolution of the cylinders. This increases the rate of production but has no effect on the machine's minimum width.

Other Features Sheet prefeeders and bundle unit formers have taken much of the sweat out of box production. These developments have enabled fewer people to make more boxes, which translates into a considerable increase in productivity. The prefeeder operator is mainly concerned with keeping scrap and crooked sheets out of the flexo feed hopper. The operator has time to check on the ink and glue while the machine is running. The offbearer merely slides bundles onto a shelf, which withdraws to form a unit on a descending lift. One person can easily slide off 12 bundles per minute, which leaves the operator time to check on quality and keep one eye out for stacker problems. Two people cannot watch everything that happens on an 80-ft.-long machine, but a series of jam detectors gives them the confidence to run up to speed without great risk.

The no-sweat operation has been extended to feed conveyors and exit conveyors. Some plants have automated conveyor storage. The prefeeder operator need only press a few buttons to have a "smart car" deliver the proper loads. Finished loads are ejected from the unit former and enter the finishing line system that moves them to the bander.

The earliest flexos had washup systems but they often required considerable scrubbing to get the pans clean. The newer systems not only clean better but use less wash water. Automatic viscometers had been used as far back as 30 years ago, but problems had been encountered, and they disappeared for a while. Currently, there are automatic controls in use that continually measure and adjust not only viscosity but pH as well.

Correction: The folder-gluer pictured in last month's Technology & Trends (page 36 bottom) should have been labeled "International Paper Box Machinery."

Howard Bessen is an industrial engineering and management consultant based out of Port Chester, New York. Of his 40 years in the industry, he has been a consultant for more than 25 years and has authored texts and articles for numerous publications. Tel.: 914/937-2545; Fax: 914/937-8646.

Following is a partial guide to suppliers of flexo folder-gluers.

Capitol Converting Equipment Inc. offers the Ichikawa line, reportedly designed for high productivity, efficiency and rapid setup. From 25 in. x 64 in. to 200 in., Ichikawa offers full NC control; side-guides, back-stops, pull-collars and slotting and scoring heads can be pre-set or repositioned automatically for the next job while the machine is running. Phone: (847) 825-7891; Fax: (847) 825-8661.

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EMBA Machinery Inc.'s new 245 QS is an in-line machine designed for quicker running speeds and setup times. The new Magna vacuum slotter-creaser unit, combined with the EMBA vacuum transport system, means full vacuum sheet control from blank to box. According to the company, the result is no board crush and top-quality print and folding. Phone: (770) 935-7360; Fax: (770) 935-7366.

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Langston's Saturn, available in 37 in. x 97 in. and 50 in. x 113 in., features a patented chambered doctor blade ink metering system; Langston's Ink Management and Graphics Enhancement System (IMAGES); and the patented Rotofold folding system. The Titan is available in 66 in. x 115 in. and 66 in. x 130 in. with one- to five-color stations and an optional rotary diecutting module. At 88 in. x 195 in., the Titan Jumbo is designed for the production of bulk bins and furniture and appliance boxes. Phone: (609) 795-7100; Fax: (609) 795-0652.

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Martin, a member of the Bobst Group, offers the Rapidset printing unit with vacuum transfer for the Midline 924. The Midline features the PCD folder with vacuum transfer, multi-T belts and electronic devices for MPC2 setup. Martin also introduces the FFG-66, its latest converting line for folded and diecut boxes. Also, the Martin top counter-ejector for in-line diecutting, which is retrofittable on any FFG. Phone: (973) 226-8800; Fax: (973) 226-8625.

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MHI Corrugating Machinery Co. offers the Summit II, which reportedly produces up to 300 boxes per minute. According to the company, 9,000 different jobs can be stored in the machine's memory and order changes can be completed within five minutes. The machine is engineered for gap control and accurate squareness on sheets up to 40 in. x 100 in. Its dialogue-style monitor displays all critical information. Phone: (410) 584-7990; Fax: (410) 584-1252.

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Serenco Inc. offers automated flexo folder-gluers for small and large boxes, up to 88 in. x 200 in. The company recently introduced the Centurion line, which features high-production platforms. Also new this year is the Serenco downstacking counter-ejector with complete operator control via servo drive controls. Phone: (410) 785-9999; Fax: (410) 785-0999.

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Tecasa's fully automatic Starprint line features bottom printing technology, board caliper adjustment, zero positioning of all modules in the line, ink viscosity control, automatic slotter and option of an in-line diecut unit. The machines are controlled by a central computer, which enables order changes and setup from a database of stored jobs. Phone: Tecasa Spain (34) 943 697147; Fax: (34) 943 697150; Phone: Tecasa USA (630) 455-9810; Fax: (630) 455-9811.

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United Container Machinery offers the Robotix, which incorporates a newly designed slot-score station configured in a score-score-slot arrangement. Head setup is acquired robotically with a single actuator. The slot-score design reportedly allows for instant computerized setup of various arrangements of scores and slots, in-line as well as off-set, and the ability to vary the score width without tooling change. Phone: (410) 592-5400; Fax: (410) 592-5460.

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Ward Machinery Co.'s IntelliMatrix range has a modular design that enables upgrades by adding options, retrofits and additional sections. The machines are designed for high-quality graphics and feature Command Dynamix computer control with on-screen machine documentation. Also, a top-loading counter-ejector that handles complex diecut folded boxes and flat diecuts up to 82 in. wide. Phone: (410) 584-7700; Fax: (410) 771-1552.

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When it comes to flexo folder-gluers, speed is of top concern among box- and cartonmakers, whether through retrofits, rebuilds or the purchase of new machinery-the latter option seemingly emerging as a favorite.

"Quick setups are crucial today," said Jack Lynch III of Fitzpatrick Container Co. in North Wales, Pennsylvania. The 71-year-old independent company has two, two-color flexo folder-gluers, one of which was purchased last year while the other is about 20 years old. "You want to get your orders on and off the machine as quickly as possible, and some of the newer flexos today have four-minute setups. That's where you want to be."

Lynch's older flexo doesn't have those quicker set-up capabilities, but it has been enhanced with new ceramic anilox rolls and a new counter-ejector. While it has worked hard for the company over the years, it will most likely be replaced, soon, by a new flexo . "New equipment is the future, because you want to try to be more cost-efficient," Lynch said, and the antiquated machine simply doesn't have the framework for the speed the company seeks. He added that one of the best features on his newer flexo is an in-line diecutter, which is set on a track and can be rolled in or out, depending on production needs. "Jobs that we were taking from our rotary diecutter and bringing over to our flexo we are now making in one pass."

Joe Benes, engineering manager at Fellowes in Itasca, Illinois, is quite familiar with that two-step process. Before the 82-year-old independent company purchased a new, two-color flexo with a built-in diecutter, it used conveyors to carry product from a printer/diecutter to a separate folder-gluer. The new machine's design has increased the company's capacity by 25%, Benes said.

Benes also likes his flexo's downstacking feature. Because the company specializes in filing and storage boxes, it cuts countless handholes and flaps that can jam up a machine's stacker, especially in a bottom-to-top design, he said.

The company has also added a dual-feed option. "With the standard lead edge feeder, we produce about 9,000 sph. With dual feed, we can run at 50% our usual speed, but still get 9,000 sph," Benes said. "We can run slower with less wear and tear and less maintenance, but we can produce more pieces."

C&B Corrugated Containers Inc. in Mississauga, Ontario, Canada, switched from a direct-press printing method to flexo five years ago because of flexo's quick drying characteristics, said co-president and owner, Larry Cooper. The 14-year-old independent company has since bought two used flexo folder-gluers, both straight-line machines with two colors, that it has retrofitted and rebuilt. Among the upgrades were the installation of new glue heads and belts and non-crush rollers, which replaced solid, urethane rollers.

The used machines, purchased largely for economic reasons, have greatly helped the company grow-to the point where it is now ready to invest in new, computerized equipment. C&B's current machines are not computerized; it can therefore take the company 35 to 40 minutes to set up a job, Cooper said.

"We bought the flexos to protect the RSC business that we already had, but also to improve our productivity and to compete in different markets," he said. "We have achieved those goals and we've gotten to a level in the last five years where we're now ready to move on to higher speeds and minimal setups."