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The Conversion of Corra Gator-Boardy-Part 2

Part 2: Printer Sections

images are transferred from the print cylinder to the corrugated board

This is the second installment in a series by Jim Brown, a corrugated equipment specialist with more than three decades of experience. Articles will outline what the board experiences during the conversion process, but from an unusual perspective: that of the board itself, in the form of our imaginary narrator, Corra Gator-Boardy.

Ride along with Corra in a series of six mini-adventures on her way from a flat corrugated board to an amazing, corrugated container. Learn about the mechanisms and devices that will launch her into the machine, color her panels, cut out her unique shapes, form her dimensions, hold her together, and prepare her for market.

In our last adventure, Corra had been loaded and launched out of the feed section of the machine, was up to proper board speed, and headed into the first print section. She looked up to see a series of roller wheels, this time positioned above her. These were made of smooth, hard-anodized aluminum. As she advanced into the first print section of the machine, a vacuum blower pulled her tightly against the wheels that protruded through stainless steel grate openings above her. She was traveling at the exact same speed as the surface of the feed rolls.

Just ahead was a second nip, the impression nip. This was the gap between the smooth, chrome-plated, nine-inch diameter impression roll above and the print cylinder below. The print cylinder was wrapped with a custom, soft, urethane print plate that had an image of slices of fruit and some wording engraved into it. The image was coated with a film of yellow, water-based ink. As she rolled forward, the image was transferred onto her outer liner at exactly the right speed. The impression roll helped to ensure that the image was impressed the perfect amount onto her outer liner. Unlike the other nips, this nip is adjustable by raising or lowering the entire upper blower/roller assembly that also contains the impression roll. Just like the feed roll nip, the impression nip pressure must be very precisely adjusted. If it is too far open, the print will skip. If it is adjusted too tightly, the print will create a smudged image.

Corra was really excited now. She had some yellow color and was heading for red! It was a peaceful transition from print unit one into print unit two. She had time to reflect on how the ink had been pumped from the ink bucket to the single blade ink chamber, where it had filled the cells of the anilox roll. The surface of the anilox roll has tiny, reverse pyramidal-shaped cells that are laser engraved into the ceramic-coated surface. There were 250 cells in one linear inch of roll, with the volume of ink that each cell could hold measured in billion cubic microns. Next, the excess ink was “doctored” off the anilox roll surface by the doctor blade to create an ink film of precise thickness that would transfer onto the print cylinder plate.

The doctor blade is the width of the anilox roll and made of plastic, with a bevel on it, much like a disposable putty knife. The main ink flow, along with the ink scraped off the anilox roll, runs out of the ends of the ink chamber into the ink pan and is pumped back to the ink bucket. The ink pump works like a human heart, with check valves that open and close as the pump cycles—first drawing in ink, closing, and then pushing it out.

this schematic illustrates the mechanisms of ink application to the roll

Now she was ready to receive red ink from a print plate that was slightly different, but complementary to the yellow one. And in a flash, half of the fruit image turned orange as the red printed over the yellow. With just enough time to let her ink soak in and dry, she raced through print two and headlong into print three. She was a pro now and was prepared to receive a nice heavy coat of black ink, which made her new image pop. But how, Corra wondered, are my colors aligned?

She remembered learning about a print registration datum target. This is a bullseye symbol located in the same spot on all the various color print plates. It demonstrates if the various print unit plates are positioned correctly in relation to one another. There is usually some small amount of acceptable error left and right (lateral registration) and up and down (rotational registration).

the arrow on the board indicates the direction of travel

To adjust the lateral registration, a print cylinder and its plate must be moved left or right using the lateral adjust mechanism. It is commonly a manual apparatus with a threaded adjust shaft and an aluminum handwheel. When you turn it counter-clockwise, the print will move slightly to the operator side of the machine (where the operator stands). Conversely, a clockwise turn of the handwheel will move it to the drive side of the machine (where the drive motor is located).

Changes in rotational registration require the print cylinder and plate to be advanced clockwise or retarded counter-clockwise. This is accomplished through the print register, which is a motorized differential device. Some are sophisticated, servo motor-driven, harmonic drive units, whereas the older ones are worm gear, electric motor-driven devices. Both lateral and rotational registration can be done with or without the machine running. When the first sheet is run, an operator can measure the amount a color is off and make the necessary adjustment, until all colors are printing as close to on top of one another as possible. The datum target shown in this article is a sample of cyan, magenta, yellow, and black showing their positions, relative to one another. This will affect the accuracy of the images on the sheet, a visible measure of quality.

Next, things will be getting much more intense, as our corrugated sheet will soon fly into the sharp teeth of the die cutter section.

Jim Brown has more than 30 years of experience in engineering and machine design for the corrugated industry. He is currently the Manager of Purchasing at Sun Automation Group.

Originally published in Paper360°,  March 2023

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The Conversion of Corra Gator-Boardy

Part 1: Feed Section

This is the first installment of a series by Jim Brown, a corrugated equipment specialist with more than three decades of experience. Articles will outline what the board experiences during the conversion process, but from an unusual perspective: that of the board itself, in the form of our imaginary narrator, Corra Gator-Boardy. Corra’s journey will include six adventures:
  1. Feed section
  2. Print sections
  3. Die cut section
  4. Slotter section
  5. Folder section
  6. Counter-ejector section

The series creates an engaging way for those within the corrugated industry to gain insight into processes outside their area of specialty, as well as to offer the next generation of professionals or those in related industries a chance to gain more understanding of the process as a whole.

Ride along with Corra in a series of six mini-adventures on her way from a flat corrugated board to an amazing, corrugated container. Learn about the mechanisms and devices that will launch her into the machine, color her panels, cut out her unique shapes, form her dimensions, hold her together, and prepare her for market.

Corra Gator-Boardy began her life as two outer layers of kraft paper glued to a fluted center with starch water and steam (Fig. 1). She was then quickly cut to length by the corrugator cutoff knife, where she officially became a corrugated board.

a fig from there she traveled through the box plant
Figure 1

From there she traveled through the box plant conveyors with many others, destined to become something special. Corra had learned all about her imminent experience: how in the flexo-folder-gluer converting machine she would pass from the feed section, through the printers, die cutter, slotter, folder-gluer, and counter-ejector to finally become a valuable corrugated container. It sounded very exciting, but it was a little scary. She did not know exactly what she would be experiencing during this multi-step process.


Corra was carried up from the plant conveyor onto the prefeeder. The prefeeder shingled her and the rest of the board into the feed section hopper. The hopper is the area between the left- and right-side guides and the feed gates. Corra dropped into the hopper. Her forward movement was stopped sharply by the pair of shiny feed gates. Her belly was pressed against a series of cast aluminum support grates covered with thin, stainless steel wear strips. She was next to be fed into the converting machine.

She saw the machine operator press the feed button. The 100-horsepower motor that was driving the gear train for the entire machine was just about to engage the feed unit. She could hear the air from the vacuum blower whirring around her.

a figure suddenly the grates dropped her onto
Figure 2

Suddenly, the grates dropped her onto a series of urethane wheels supported on several rows of stationary wheel shafts (Fig. 2), and she could see that there was just enough gap below the feed gates to allow her to move forward when the time was right. Without warning, the wheel shafts began to rotate very quickly, and she was accelerated violently from zero to 1,000 feet per minute!

With vacuum pulling her down as well as the weight of the pile of board above her, she was hurled forward into the first nip. A nip is the gap between any two rollers in the machine, the first of which is the feed roll nip. The upper feed roll is covered with soft urethane that grips the board and provides pressure against the lower feed roll. The lower roll is steel with a straight knurl on its surface, a fine series of grooves that run across it (Fig. 3). The pressure between the rolls is adjusted by raising and lowering the upper roll, creating a gap just slightly smaller than the thickness of the board, but not so much as to crush the flutes inside.

a figure operators can raise or lower any of the adjustable shafts
Figure 3

Operators can raise or lower any of the adjustable shafts in the machine using a pair of matched, eccentric housings. The shaft ends are supported on bearings that are fitted into the hole (bore) of the housings, except the bore is machined off center in the housings on purpose. That way, when the housings are rotated in the frames, the adjustable roll moves through an arc, which opens and closes the nip.

The feeder transmission provides both the lifting and lowering motion of the grates as well as intermittent rotary motion of the wheel shafts, all in perfect timing. It is driven by the machine’s main drive and subsequent gear train. The input shaft runs at constant velocity. There are lowering and lifting cams inside, which are round with a gradual lump on them. A cam follower bearing runs on the edges of the cams and is attached to a linkage that, in turn, raises and lowers the grates. A small, external air cylinder (interrupter cylinder) lifts the cam follower off the cams to interrupt the grate motion, which stops the machine from feeding more board.

For the intermittent rotational motion of the wheel shafts, there are custom shaped, adjustable position cam lobes on the input shaft. These cam lobes mesh with a cam follower wheel on a parallel shaft. As the input shaft rotates the cam lobes, the engagement and disengagement of the lobes in the cam follower wheel creates an intermittent rotational motion, which is then transferred by gears to the wheel shafts. This is commonly known as an indexing box (Fig. 4).

a figure the timing is set so that the wheel shafts are stationary

Figure 4

The timing is set so that the wheel shafts are stationary as the next board is dropped onto the feed wheels. Once the full weight of the board is released onto the wheels, the intermittent motion begins. This on-and-off motion keeps the wheels from spinning during the moment of contact with the board. Then it accelerates very quickly to board speed, and repeats the process for each sheet that is fed.

What an amazing device, Corra thought. It accelerates the bottom board from zero to board speed as fast as 400 boards per minute. That’s over six boards per second!

Once Corra is launched into the feed roll nip she is travelling at the correct machine board speed, and begins a more comfortable, constant velocity ride through the machine. The feeder’s job is now complete and prepares to feed the next board in the hopper.


Corra’s next adventure will take her through the printers, a calmer experience that will paint her in living color. Join us in the next adventure to learn precisely how that happens and where she is heading after that.

Jim Brown has more than 30 years of experience in engineering and machine design for the corrugated industry. He is currently the Manager of Purchasing at Sun Automation Group.

Originally published in Paper360°,  January 2023

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Why the Corrugated Industry needs Machine Learning Technology

As the capability to make industrial machines more intelligent improves, there are now more reasons than ever to invest in technologies that will future-proof your equipment. The retirement of many veteran machine operators coinciding with the influx of new, undertrained workers is at the root of many headaches for converters today. An increase in unplanned downtime, operator safety risks and machine maintenance costs are just some of the consequences of this staffing predicament.

However, the traditional operator challenges plaguing the industry these last few decades are issues that have been solved in many other manufacturing sectors through technology. So why not in corrugated too?

There are now IIoT (industrial internet of things) solutions designed to increase your bottom line and compensate for the qualified operator shortages in the corrugated sector. With remote monitoring, machine learning and artificial intelligence, IIOT can not only read and report your machine data, but over time can learn and predict maintenance needs to your production staff. This is the kind of visibility that allows staff to make more informed, strategic decisions for the betterment of your organization.

 Mitigate workforce challenges

As more veteran operators are rightfully entering retirement, converters are finding their skills and experience incredibly hard to replace. Their experiential knowledge acquired through many years of operating the same converting equipment may have never been passed down, walking out the door with some of your best people. As younger, less-skilled operators and maintenance technicians move into those positions, you may have noticed that your operations have become a bit more clunky and inefficient, since they simply don’t know the quirks and tendencies of the machines.

Corrugated IIOT technology brings the power of machine learning and artificial intelligence to your production floor, providing actionable insight used to optimize your fleet operations and maintenance activities effectively. The software acquires a wealth of tribal knowledge as your team interacts with it, training the machine to later predict machine failures and suggest submitted resolutions – educating operators for years to come. In the age of endless information at your fingertips, it’s time to use that technology to capture and share key equipment knowledge that keeps your operators safe and your presses running.

Increase your bottom line

As your operators become more skilled and informed by IIoT systems, the results are simple: cost savings and reduced downtime. With the average cost of downtime at $1,000 an hour, according to industry benchmarks, you need to keep your unplanned downtime to a minimum to remain profitable. IIot software is capable of saving time and costs by notifying your team of optimal maintenance intervals, allowing your team to consolidate schedules for maximizing your technicians’ time. Additionally, the visibility provided by IIoT software allows your production staff to quickly identify machine anomalies and, overall, optimize your fleet and staff. Multiply these efficiencies across multiple machines, and your production floor’s ROI increases dramatically.

Connect and inform leadership

Visibility is the key to informed decision making. Being aware of your production numbers, unplanned downtime, maintenance schedules and more, is crucial to optimizing your production floor for efficiency. With corrugated IIoT software, your production staff have the machine-learning tools they need to capture and predict important events driving the productivity and safety of your converting equipment. However, without this technology, equipment knowledge tends to be siloed, maintenance schedules are based on tradition rather than data and your operations slowly fall behind the competition. Effective leadership is informed leadership and with the machine-learning technology of corrugated IIoT software, your staff will have actionable data to structure their fleet and team for maximum productivity and profitability.

The future is here

The cost of a single converter developing an IIoT machine learning software for their plant is simply unreasonable – it would take years to see your ROI. But unless you’ve purchased new capital equipment in the past few years, your existing machines may not be equipped with the technology needed to digitize your operations and data. That is why Sun Automation has created a IIoT, machine-learning solution for converters seeking visibility into their machine and operator performance – Helios. In 2021, Sun Automation launched Helios, a AI/machine learning platform that monitors, learns, and predicts important events driving the productivity, safety and profitability of your corrugated equipment. We are excited and eager to bring the power of IIoT to the corrugated converting industry! Visit the helios website to learn more, calculate your ROI with Helios and schedule a live demo >>> www.gohelios.us


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