By Cassandra Balentine
When it comes to superwide format graphics, the step of seaming to finish edges or bonding multiple substrates together is commonplace. Welding is a finishing process that comes after hours of production, errors are costly and painful at this stage of the game. Therefore, skilled precision and reliable equipment are imperative for seaming wide format graphics.
Because the process of welding creates bonding at a molecular level, it is a popular method for finishing digitally printed output. Popular types of welding include radio frequency (RF) for polyvinyl chloride (PVC) or polyurethane (PU) coated materials; sonic—or ultrasonic welding—for polyester fabrics, Tyvek, and mylar; and hot air/hot wedge for PVC or PU banner material.
Marcus Tam, marketing officer, Eastsign International Ltd., notes that hot air welding generates hot gas to create a bond between two layers of media, while RF welding generates radio waves at certain frequencies to bond two layers of PVC materials.
Hot wedge welding and impulse methods are also available. Truy Pham, U.S./Canada sales manager, Miller Weldmaster, describes hot wedge welding as a heated wedge positioned at the weld point to provide the required heat. “The fabric/media is then pulled across the heated wedge, creating a perfect weld,” he says. Impulse welding uses an impulse welding machine to apply pressure to the seam area by two impulse heated bars.
“Heat is created by pulsing energy through the heating element in the top and bottom bars for the duration of the weld,” he adds.
Welding is ideal for grand format applications because it creates a permanent, durable bond that withstands harsh climates that these graphics typically encounter. Additionally, it provides a more efficient process when compared with sewing.
A handful of vendors offer solutions using the various methods. Here are highlights from some serving the grand format digital printing space with welding equipment.
Eastsign offers both hot air and RF welding/seaming equipment. For its hot air products, the maximum temperature is approximately 1,202 degrees Fahrenheit. According to Tam, it is possible to weld material up to two millimeters thick.
Its RF product welds PVC-based materials. The welding width is 20 to 40 millimeters. Maximum speed is 13 feet per minute. Tam says that it is possible to produce multiple layers welding up to 0.1-inch thick since welding generates pressure on the material.
The RF machine features a working table of up to 80 feet, enabling the production of extra wide PVC mesh for construction sites. “RF creates strong bonding between PVC materials, which is suitable for applying it outdoors,” adds Tam.
Steve Winklen, SVP, sales, North America, Forsstrom, says RF fuses plastic materials together. Substrates typically include PVC vinyl, which features properties that react to RF like water molecules react to microwave ovens. “In simplified terms, because these materials have a polarized molecular structure, they react energetically to the power provided by the RF generator. The molecules then vibrate to a level where they heat up due to friction from interaction with each other.”
The company’s Web site describes the RF—or high frequency (HF) process as the joining of material by supplying HF energy in the form of an electromagnetic field and pressure to the material surfaces to be joined. A generator produces the energy.
The Forsstrom TDW range is one of the company’s most popular models. It is a large traveling machine with customized table length. There is 750 millimeters of free space behind the electrode. The welding table is equipped with a large trough for material storage.
With its fast machine movement, the ability to pre-program welding cycles, and the option to switch the machine over to automatic welding, the TDW range is suitable for large products with long, straight welds.
JTE Machine Systems
JTE offers multiple types of RF machines as well as ultrasonic machines. The company also collaborates with hot wedge machine suppliers for customized and integrated solutions. In addition to new machine solutions, it keeps a number of previously owned machines on hand for customers just starting out or with budget constraints.
With more than 20 years serving digital printers, Traci Evling, president, JTE, states that the company is well versed in the challenges of achieving high-quality welds when finishing various grand format products, including billboards, building wraps, and banners. “In the past, digital printers had to rely on antiquated, stationary RF welders that produced unsightly welds, or high-skilled sewing machine operators to finish their printed products,” she recalls.
To address this market, the company offers the FIAB 900 traveling RF welder. The system includes an integrated modular table and track system of almost unlimited length, says Evling. However, most are around 65 feet—or 20 meters.
For those with extra large projects, two FIAB welders can travel on one long track and table system. The FIAB 900 features an easy-to-use, full-color, ten-inch touch screen control panel, which enables operators to recall named recipes.
JTE is the exclusive North American distributor for FIAB, offering 24/7 service.
A few years ago, Evling says the company introduced a specialized RF welder for small pockets, hems, splices, splines, and zippers on banners. The JTE 6kw RF Banner shuttle system includes an integrated sliding table with front trough and magnet strips for holding the material as it is pushed through the RF welder, welding five feet every few seconds.
For polyesters and other thermal plastic materials like Tyvek and mylar, JTE offers the JTE Ultrasonic bar welder and the JTE Sonic Sew-N-Cut, which is designed to provide an easy, reliable, and cost-effective method to weld flags, banners, and fabric signs without sewing.
Miller Weldmaster provides heat seaming solutions for grand format print providers. The company offers hot air, hot wedge, and thermo impulse welding equipment.
“Miller Weldmaster offers a solution for every wide format print provider,” says Pham. “Whether you service 2,500 banners per day, 150 billboards, or the occasional party banner, we have a machine that can help a grand format print provider be more efficient,” he adds, pointing out that the company manufactures economical solutions for smaller printers as well.
The company also offers fully automated solutions that can finish an entire roll of printed goods. “Our Autobond machines align, weld, cut, and grommet in one station, leaving a finished billboard at the end of the line,” says Pham.
The company’s 112 Extreme model features many options that make it well suited for welding building wraps. The machine is built to the length requested by a print provider. Pham says the typical size of 60 feet easily welds large billboards and soft-sided truck graphics. The 112 Extreme welds tile images much larger than the length of the machine. A vacuum welding track holds materials in place to reduce the amount of labor needed to handle large graphics. The laser alignment tool ensures that images are accurately aligned for perfect registration. A laser guided rotary trimmer allows users to trim materials on the bed of the machine to avoid workers having to cut a big graphic on their hands and knees.
Importance of Accuracy
Based in Bloomingdale, IL, ER2 Image Group is a full-service grand format printing company. The shop’s mission is to provide a one-stop shop for the design, creation, and installation of customer projects under one roof.
The company celebrates 22 years in business, but recently rebranded as ER2 Image Group. A family-owned and operated sign shop, it employs approximately 55 people. It specializes in out-of-home advertising and specifically grand format output.
Gary Schellerer, VP, operations, ER2 Image Group, estimates that approximately 60 percent of its volume consists of what would be considered grand format output. Of the additional 40 percent, about half of that directly supports its grand format output in one way or another.
ER2 Image Group relies on a Miller Weldmaster 112 Extreme to help finish graphics. “We chose this unit because it gives us the ability to weld the edge of a banner up to 20 feet wide in one pass without moving the banner,” explains Schellerer. “The unit also seams webbing, ropes, or pole pockets into a banner. It includes a hydraulic grommet that grommets a banner without moving the panel,” he adds.
When searching for a welding solution, Schellerer recalls hearing good things about Miller Weldmaster and felt the company was well respected for its offerings in this area.
Schellerer says the main advantage of these units is when used with large panels; the panel remains stationary while the welder passes over the banner. “Finishing large panels can be difficult when using a traditional sewing machine because the panel has to move through the machine,” he describes.
He points out that navigating a grand format panel through a sewing machine can be challenging. The ability to finish the panel without moving it creates an efficient scenario. “I would say that the one thing that would be difficult to do without this unit would be the ability to accurately align large panels together while maintaining exact print registration,” adds Schellerer.
Another print provider that relies on welding equipment to finish its grand format work is Big Impressions Graphics, based in Bryant, AR. The company began in 2000 to fill a void within the local wide format printing industry. Its core services are based on wide format digital print, with each of its devices offering a specific range of output. Its main focus is grand format, where it offers printing of both rigid and flexible media.
To finish graphics that require seaming, the company has used various solutions, including traditional sewing as well as RF and hot wedge welding, which led them to the purchase of a Miller Weldmaster 112 Extreme hot air system. The machine features an automated grommet press and at 70 feet, can produce a single, full-size billboard in minutes, as well as easily handle standard 4×8-foot banners.
“This is the largest and most versatile unit we have to date. We would not be able to produce the variation of finishing services without this. It features programmable recipes so that speed, temperature, and other related settings can be sorted within the touch screen,” explains Scott Wallace, production manager, Big Impressions Graphics. “It allows us to program multiple steps and automates those such as turning on and off the vacuums, clamping systems, and auto return once the setting reaches its set point.”
Wallace notes that when it comes to finishing, a multitude of tricks are used. Each are based on the type of material, the desired weld, and whatever it takes to produce what the customer has requested. “That said, with a unit like this, you don’t need any special tricks, it’s simply the right tool for the right job,” he adds.
Overall, the 112 Extreme increased productivity for Big Impressions Graphics, as well as eliminated the need for three sections of the shop previously dedicated to cut, weld, and grommet functions. “With the 112 Extreme, we morphed all three work areas into a very small area that now allows us to complete all three processes within the same footprint of the welder. This is something we didn’t consider prior to making the purchase, but allowed us to utilize the desperately needed floor space.”
A Perfect Bond
Grand format print production encompasses much more than an image. The final look of a piece reflects on the print provider as well as the client.
Print providers have options when it comes to putting the final touch on a grand format graphic. Creating seams with a heat method has its advantages, but also requires skill. Continued automation adds features such as laser guides, programmable memory, and vacuum holds that makes the completion of a project that much more efficient.
Dec2014, Digital Output