By Cassandra Balentine
Digital label printing enables variability and cost-effective short runs, which are attractive attributes for big brand owners looking to test new products or hit new demographics. On the other end of the spectrum, it provides start ups and small businesses with an affordable option for dressing their products. Many digital production presses support label production, however effective finishing is critical to profitability.
Two primary finishing considerations for digital label production include cutting and coating. For this article, we focus on the former.
Above: Xeikon, a division of Flint Group, designs, develops, and delivers web-fed digital color presses for label and packaging applications.
A variety of different cuts are requested for labels, including die, perforated die, butt, and single. Die cutting around the shape of a label, slitting to separate the lanes, and cross cutting are all essential cuts for label production. “Apart from that you might need to make cuts within the label as part of the design. This would either be part of the die cut plate or the laser template,” offers Donna Covannon, director of marketing, Xeikon North America.
Die and butt cuts are two of the most prominent types of label cuts. With die cutting, labels feature a gap or space between each unit, while butt-cut labels are separated by a single cross-direction cut to the liner without a matrix existing between the labels. Juan Kim, CEO, Valloy Incorporation, explains that butt-cut labels minimize media loss and the process tends to be easier and faster. However, there are limited cases for the application. Labels are mostly die cut, and kiss cuts leave the backliner to hold the labels as a carriage. Full cuts need to be applied for sticker pieces or perforation between labels.
Jay Larsen, GM, director of R&D – digital hardware division, INX International Ink Co., says cut types can run the gamut from traditional, simple rectangular or circular cuts to cuts as intricate as lace. “Today’s laser-based cutting systems make it easy to create any cut shape imaginable—without incurring any additional makeready or preparation costs. As finishing machinery improves, customers begin to expect the production of complex cut designs at a low cost to become commonplace,” he states.
Andre Blais, label sales account manager, Heidelberg, points out that for large in-mould labels (IML), as well as small volumes, rotary cutting is quite popular. One advantage of rotary cutting—depending on the label shape—is the material can be arranged in an interlocked layout of labels.
High die punching—or cut to stack—is another essential function for label production. “The technology used depends on the method of printing, production volume, and label size and shapes,” says Blais. He explains that high-volume labels are primarily finished with cut-to-stack solutions. High-volume IMLs are also produced this way.
“A majority of labels produced on narrow web machines are pressure sensitive and finished with inline rotary die cutting devices. This process cuts the shape of the label through the top sheet, leaving only the liner intact for label application equipment,” adds Blais.
Many label presses, including flexographic, hybrid, and digital systems incorporate finishing/cutting inline. However, nearline and offline configurations are also utilized.
Covannon says there are two important elements that decide whether the cutting should be performed inline or offline—irrespective of the process. The first is speed of the individual units, for example printing presses versus converting, putting all the devices inline may reduce the full line’s speed to that of the slowest device. The second is job length and turnaround times. Smaller jobs often require more flexibility on the converting side.
Victor Gomez, director, industrial labels, Epson America, Inc., says the decision to go in, near, or offline depends on the business model and the profile of the company. “The answer of offline versus online is straightforward at the extremes,” comments Gomez. Inline is great for web to print, while offline is for shops that outsource the finished stages. The majority of converters don’t operate in the extremes. He explains that ideally, the throughput of the component pieces of inline equipment will be roughly equivalent. “If there is a mismatch, one device is beholden to the speed of the other. Offline will tend to maximize the throughput of each process. The more processes you string together inline, the longer it takes to recover from errors.”
“Die cutting inline is almost always done when printing on a flexographic press due to run lengths,” says Blais. “When die cutting inline on a digital or hybrid press, the changeover time is longer because of the die setup. An analysis of work mix, equipment investments, and labor required to run multiple machines should be done to determine the lowest cost method.”
For short-run, low-cost products—like many labels today—Larsen says finishing inline versus offline can make the difference between profit and loss on a job, or even being able to get the job in the first place. He points out that digital printers with inline laser die cutting enable the cut to be part of the artwork and pass directly through from artwork to the laser with no setup. In this case, having the laser cutter inline with production means no additional setup and finished labels. “One of the unique capabilities of some laser-based cutting systems is that every cut can be unique. When customers learn of this possibility, creative minds begin to think of new marketing possibilities and even completely new business.”
Blais states that die cutting inline reduces the overall time to produce the finished label, with less labor and waste. He says cutting inline takes place primarily on web printed labels. However, the speed of the printing process has to eventually be reduced in an inline configuration. “Collating and making proper stacks of the labels is challenging and very labor intensive,” he adds.
Inline is good for business models built around quick turnaround—when you want as few processing steps as possible. “It is great for similar, repetitive, consistent jobs,” says Gomez. If you are covering multiple sectors with varied sizes and media types, you will most likely require versatility.
Larsen believes very few challenges exist with a well-integrated inline production system. “If the digital printing system is directly coupled to the laser or traditional die cutter, all the registration can be handled electronically with no trigger mark required,” he says. Though minor, gaining the extra few millimeters of printing width can sometimes enable the printer to accept a job or change a step-up to save time and materials. “The direct coupling allows registration to be set without optics, sensors, or adjustment of a sensor to read a mark.”
Larsen adds that a traditional rotary die cutter can also be put inline in the same printer that contains the laser die cutter. This combination gives the best of both worlds. “Repetitive production of a traditional label shape can use the rotary die cutter and run at full speed while other jobs can use the laser for full flexibility and no makeready times.”
A limitation to inline cutting is that it may lead to a finishing bottleneck, as the machine will only print as fast as it finishes. “Laser die cutting speed is determined by many factors, including materials type and thickness, laser power, focus, and mirror speed. When selecting the laser system, consider what specifications are needed to meet the speed requirements of the rest of the system. The other thing to consider with inline laser cutting is that certain materials may not be able to be cut with a laser, resulting in the need for an additional inline or offline rotary die cutter,” notes Larsen.
Kim also points out that while it’s convenient to have fully finished labels from a single process, there can be speed loss of the printer or cutter in order to synchronize them. “More intelligently, recent machines provide automatic job changes by printing and sending barcodes with ticket information.”
Depending on the label size and layout of the sheets or web, Blais says it is almost impossible to achieve a similar speed as with the printing device. Label size also has a major impact.
“Organizationally and depending on the type of label, a specific converting line will be used regardless of the printing technology, meaning it will always staff offline,” comments Covannon. She says label converters are asking for more end-to-end solutions. “We can see the increasing volumes for digital label production lead to a dedicated production line for a certain application. In which case, the finishing will be inline.”
There is something to be said for cutting offline. Kim says this enables the operator to adjust the tension more precisely and allow for better and more stable finishing including lamination, UV coating, die cutting, foil stamping, matrix removal, slitting, and separation. “If cutting speed varies in synchronization of printing speed, load in tension can be influenced and slitting can be irregular between steps.”
Digital production remains a small fraction of the overall label production market, but it is a segment that is growing. To accommodate digital, label printers and converters have many factors to consider.
One major advantage of digital print technology is its ability to handle variable data printing. Because of this capability, finishing vendors have also been pushing to reduce makeready in order to enable more cost effective, short, variable runs. Larsen points out that in the case of laser die cutting, it is traditionally done offline and setups were changed easily, but only between jobs. When integrated with digital printing, the print system can pass the die lines to laser for each label, allowing low-cost production of job runs as short as one label,” he adds.
To minimize the tooling costs and changeover time, semi-rotary die cutting systems are most common on narrow web digital presses, according to Blais. “The semi-rotary design requires only a low-cost die plate for each new repeat or shape size.”
Working inline with the Xeikon 3030 printing press, the laser die cut unit (LDU) digital finishing solution is well suited for the productive printing and finishing of short-run labels, automatically changing from one job to another and slitting and rewinding the final roll. “A key advantage in using this digital combination is the buffer behind the press. This creates a certain independence between the converting device, the LDU, and the digital label press. If a finished roll needs to be removed, the digital press doesn’t need to stop printing. The buffer gives the operator time on the LDU when it stands still,” explains Covannon.
A variety of digital print engines are dedicated to label production. Here, we highlight features from companies that participated in this article.
Epson SurePress digital inkjet presses are agnostic in terms of finishing equipment. The company typically sees a flood coat flexographic station and/or roll lamination, semi-rotary or laser die cutting, matrix stripping, slitting, and rewinding on the finishing line for its pressure-sensitive labels. Further, options like a sheeter/stacker and conveyor would be added as needed for each application.
Heidelberg offers its sheet-fed press for cut and stack labels, and Polar cutting equipment for offline production of cut and stack labels for paper and in mould label substrates. Each Heidelberg Gallus narrow web press comes with several inline die cutting options depending on the customer application and needs.
INX, in conjunction with Spartanics, offers both inline and offline versions of most finishing options, including laser die cutting, rotary die cutting, sheeting, slitting, lamination, and coating. Machines can be designed to address unique workflow for production scenarios.
Xeikon cooperates with a diversity of partners in its Aura Partner network, but also has its own converting solutions to be used in or offline, like the DCoat, Entry-DCoat, and Web Varnishing Module.
Valloy offers the DuoBlade SX, which is a digital knife die cutter. It is an all-in-one solution that provides lamination, die cutting, full cutting, matrix removal, slitting, and separation. Tension can be digitally controlled and a web guide system is embedded by default. It is an independent digital finishing machine so in many countries it is sold with other digital printers.
Cut software helps streamline the finishing process and reduce errors.
Cutting software is an important element. “Full digital printing with laser die cutting allows the artwork creator to specify the dieline directly in the artwork. When this artwork is processed by the RIP, the die line is recognized and extracted automatically so additional steps are needed. The RIP contains setups for different media types, which allows the printer to automatically setup the laser to properly cut the chosen material,” explains Larsen.
Cutters tend to be driven by exclusive software. These solutions read cutting information in PDF, AI, or PLT formats. For example, Valloy’s DuoBlade SX digital die cutter is powered by DuoBlade cutting and AI2PLT converting software.
To overcome complexity and improve production time, Xeikon has developed Vertorizer, a software product that sends all of the required information to the laser unit. This is specifically designed to take away the complexity of job planning with laser die cutting. It will automate the whole job flow and control the laser die cutting unit, shares Covannon.
Heidelberg recommends Polar Compucut software. “Software is used to provide operators with the most efficient way to create a cutting program with difficult printed layouts. It calculates and provides the cutting program within minutes and sends the cutting program to the cutter for production,” offers Blais.
Cut for the Course
Cutting is an essential component in the label production process. A variety of cut types and methods are available. To ensure seamless production, it is important to select the right finishing process for the job at hand.
Nov2019, DPS Magazine