Light weights put heavy demands on labelers
If there’s one point on a packaging line at which some of the most challenging trends in packaging converge, it’s the labeler.
Faster throughput? Check. More changeovers? Check. Thinner materials, for both labels and containers? Check and double check.
Throw in the unchanging fact that labelers are among the most intricate, complex, stoppage-prone pieces of equipment on the line, and it’s clear why labeling can be a potential headache for anyone. That translates into increased demands on suppliers of labeling equipment.
“What customers are telling us is, ‘Hey, help. I’ve got all these labels and I’ve got to run different kinds of labels, different SKUs [stock keeping units], I want to run lighter gauge labels, et cetera, et cetera. Help us,’” says Bob Adamson, vice president of sales and marketing for B&H Labeling Systems.
Labelers often have to handle containers from one supplier, labelers from another and adhesives from a third, Adamson says: “All three of these materials with all of their inherent variations come together at the labeler, and the customer wants to put them all together at 600 a minute."
Thin is inOne of the biggest such variations has been in the robustness of the materials used for plastic labels of all sorts. End users want to go as thin as possible, for environmental reasons, and, especially, to save money.
“This is what the customer is going to want,” says Barbara Paschal, sales manager for Marburg Industries. “If you’re going to run, say, 2-mil material instead of 3, that’s a 30% price difference for that customer. And it doesn’t look any different on the container. So you’re going to have to say, OK, we’re going to run 2-mil.”
Thinner label materials are challenging because they have more tendency to stretch, which can distort the graphics and cause problems with registration, leading to misplacement. Maintaining web tension is crucial for proper labeling, but thin-gauge labels have a lower tolerance for tension.
B&H handles these problems with two types of improvements, Adamson says. Its Invation design helps B&H labelers handle different types of material. One of the key components is the “cutter shells,” perforated pieces of metal that hold the label in place during cutting. A proprietary coating allows the cutter shells to handle label materials with different coefficients of friction, reducing stretch and eliminating the need for operator adjustments.
Krones Inc., the world’s largest labeling equipment supplier, deals with the challenge of thinner labels by handling them in a more sophisticated way. Older Krones machinery maintained web tension by running the web through multiple rollers. Newer models use servo motors, guided by input from photoelectric sensors, to make minute adjustments in roller position as needed, allowing the proper tension to be maintained with less stress on the material.
Registering improvementAs for registration, B&H uses an advanced registration system for its Marathon series of roll-fed labelers. A traditional labeler’s registration is based on the assumption that the label’s position will conform to a template. The Marathon uses a vision system with programmable algorithms that can hone in on identifiable elements of the label’s graphics while compensating for slight differences in the label’s position.
Containers, as well as labels, are getting thinner, which presents another set of challenges to labelers.
“A lot of my guys complain about the thinner plastic bottles because they’re less rigid,” says Joe Golden, marketing director for Biner Ellison. “They don’t hold their shape as well. It’s harder to manufacture the conveyor systems to make sure that when the bottle goes through these machines, it doesn’t get completely destroyed or bent completely out of shape.” Biner Ellison has made various adjustments, Golden says, including adjusting the angle and force at which pressure-sensitive (P-S) labels are applied.
Krones depends on servo technology to help with thin-walled containers as well as thin labels. Machine components that used to be regulated by a mechanical gearbox, such as the unwind station, tension rollers, glue roller and cutting unit, are all run by servo motors that can maintain consistent handling at differing speeds, even with thinner material.
“When the machine speeds up, all the servo drives speed the machine up,” says Dave Niemuth, Krones’ director of labeling technology. “When it slows down, they’re all communicating together as one unit.”
When it comes to thin-walled bottles, handling of both bottles and labels must be adjusted, says Stuart Moss, director of Accraply. This could involve factors like change parts, more sophisticated registration and improvements to the vacuum system that holds the labels in place. Thin-walled bottles have to be handled with a sure touch to keep them from tipping, but a gentle touch to keep them from denting. This often requires refinements to timing screws and other parts that contact the containers, Moss says.
Some single-serve water bottles now being marketed are so thin that they’re more like water balloons. And equipment from Label-Aire treats them like balloons in one respect: It blows them up. Label-Aire’s 9000 series of in-line P-S labelers offers an “air-inflate” option that reinforces the bottles by forcing air into them just prior to labeling. “We will create the rigidity needed to label that bottle,” says Steve Winders, Label-Aire’s director of sales and technical services. Label-Aire is planning to offer the air-inflate option on its more moderately priced 6000 series.
Shrink is growingOne of the biggest changes in labeling has been the increased popularity of shrink labels. Their advantages include more vivid graphics, 360-degree coverage and the options of tamper evidence and thermal protection. Winders estimates that shrink-sleeve constitutes about 15% of the label market, up from about 5% two years ago. Label-Aire introduced a shrink-sleeve line about a year ago.
Shrink labels come in two basic forms: shrink sleeves and roll-on-shrink-on (ROSO). Shrink sleeves are either preformed or formed by the system into small tubes, which are dropped around the container. ROSO labels are loosely attached to the container, usually by UV-curable adhesive. In both cases, heat is applied downstream that shrinks the label around the container. Shrink sleeves, which have the majority of the U.S. shrink label market, usually use labels made from polyethylene terephthalate glycol (PETG) or vinyl. These materials have a shrink factor of up to 70%, which makes them more suited to containers with relatively acute curves. ROSO systems mostly use polypropylene (PP), which has a shrink factor of only up to about 20%, meaning it’s suitable only for containers with modest contours. But ROSO labelers usually can run faster than shrink-sleeve systems, and PP is cheaper than PETG or vinyl, giving ROSO an economic advantage.
Staying in controlStaying in controlAs labelers are called upon to run faster and with more versatility, control becomes more of an issue. The trend has been toward using ever more sophisticated programmable logic controllers (PLCs), as opposed to more limited microprocessors.
PLCs have two major advantages over microprocessors in labeling, says Chuck Wepler, vice president and general manager of Quadrel Labeling Systems. They can be programmed with a variety of product profiles, which makes it easy to change between container sizes and shapes. And they’re easier to standardize, both within a factory and across an entire company, especially when they come from a major manufacturer like the Allen-Bradley unit of Rockwell Automation.
A large company “comes to us and they look at our labeler with microprocessors and they say, ‘Hey, you know what, we don’t want to learn your HMI [human-machine interface],’” Wepler says. “‘We’ve got Allen-Bradley PLCs all over this whole factory and we are used to the touchscreen, we’re used to the operator interface, and we don’t want to mess around learning 97 different HMIs on 97 different machines and have 97 different microprocessors in stock.’”
In addition, PLCs are useful for monitoring a machine’s performance and keeping track of parameters like the amount of label stock remaining.
As packaging lines meet demands for speed and versatility, labelers have to keep pace. Staying on top of developments in labeling systems can help ensure that, no matter how thin bottles and labels get, a product will always be able to put its best face forward. F&BP
FOR MORE INFORMATIONThe following companies contributed to the research for this article:
B&H Labeling Systems
Marburg Industries Inc.
Quadrel Labeling Systems