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REVO Team drives Digital Flexo Revolution

Logo_REVO_TeamREVO is a Project Team which collects 7 industry Leaders cooperating to drive flexography towards the new “digital” world of Printing and Converting.  Process consistency, efficiency and cost reduction are the objectives of REVO Digital Flexo Revolution, to win the Labels and Packaging challenge for short runs, global quality and total flexibility. The REVO Project Team members have started to cooperate in December 2013, officially announcing the project in February 2014. REVO Team has selected UV Flexo, extended colour gamut and digital process automation as the three technology drivers to support flexography to become “digital” and keep its role of leadership in Labels and Packaging industry. “We want to create an industry move towards flexo digitalization” state REVO Team Members “We share together all our latest innovation, our open and cooperative approach is the key to success”. Every partner delivers a specific technical contribution to the project:

Niklas Olsson of Flint Group Narrow Web comments: “UV Flexo is the ideal process to become digital: UV inks are inherently consistent as there is no VOC evaporation to “disturb” the printing process, furthermore inks do not dry on the plates so waste is reduced and quality consistency increases. UV flexo inks printing quality is superior to water and solvent based flexo inks as less ink is transferred (ink is full solid, without VOCs). Dot gain is reduced and ink densities are higher. REVO process needs top printing quality and high colour density to achieve the best performances. New generation low migration UV Flexo inks support the REVO Digital Flexo Revolution with high pigmentation, consistent ink transfer, consistent density properties, giving to REVO projects a wide range of graphic possibilities, and excellent consistency performances.”

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Dan Pulling of Esko adds: “Extended colour gamut is the most logic solution for the flexo industry going “digital”. 7 inks always in the press. No need to change anilox or ink. No special colours, no colour matching, no waste of substrate, no press down-time. Most PMS colours can be reproduced by printing 7 colours on top of each other. With 7 colours separation pre-press can “digitally” reproduce 90-95% of PMS colours. A new era can be predicted for Flexo, fully integrated in a digital work flow, as it happens already with Digital presses. The same file can be printed on a Digital or on a Digital Flexo press, with consistent “digital” print quality, and equivalent costs and productivity on both presses (Flexo keeping a wider range of applications in medium to long runs). REVO technology also provides greater design flexibility as the same job can be printed with virtually unlimited number of PMS colours. Or 2 or more jobs can be interlocked on the same web, with total different PMS colours. REVO opens a wide range of new possibilities for graphic designers and production managers. Wide flexibility in a “digital” REVO production flow.”

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Friedrich Wolf of DuPont states: “New digital flexo plates” allow for extreme consistency and print quality. New plate qualities and modified processing work flows results in high image resolution and excellent ink transfer. The solvent free plate processing technology supports the environmental awareness of the REVO project. Fine screen rule of 80 lines per cm is the new standard, changing again the rules of our industry. The new generation digital plates provide the requested quality, thus a wide gamut of PMS colours can be reproduced, without changing the inks in the press. The final printed quality is also more vibrant, with more “natural” greens, reds, oranges and blues. New graphic opportunities to Labels and Packaging designers are available. Further to “digital” consistency and cost reduction, REVO technologies can reproduce “real” colours” which could never be achieved before.”

Nick Harvey of Apex adds: “UV flexo ink and digital flexo plates deliver fantastic and consistent quality. But inconsistent ink transfer, and inconsistency between anilox rollers might endanger the “digital” consistency of the REVO standards. In a 7 colour separation a key factor is to provide accurate consistency of the lay down of the 7 colours. New engraving technologies developed recently, resulting in the next generation anilox rollers are able to overcome some inconsistency of standard anilox designs. REVO standards need a predictable ink density which can be achieved thanks to the scientifically designed open slalom ink channel geometry which delivers an ink transfer with less than 1% tolerance. The next generation technology provides fundamental contribution to the REVO “digital” new standards. A further advantage of REVO technology is that less ink transfer is needed, to achieve the same level of opacity. By overlapping 7 vignettes instead of using full solids, ink transfer is reduced, as well as ink consumption. Ink costs, curing costs are reduced, and the whole PMS process is consistent and repeatable.”

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Federico d’Annunzio of Nuova GIDUE completes: “Extensive Digital Automation in the printing press is needed to collect all the  opportunities of the new REVO “digital” flexo process. On the printing and converting sections, servo motors and digital HD Cameras substitute the eyes and the fingers of the operator with digital eyes and digital fingers. The new generation presses exchange the print and diecutting cylinders from “old” to “new” job fully automatically, without operator. Set up and production operations are digitally controlled, with very limited intervention from the operator, which becomes a production manager and a quality tutor on the press, as most of the operations are automated and digitally controlled. Digital Automation in flexo presses completes the REVO “digital chain” from pre-press, to plates, to inks, to anilox and finally to printing and converting, to achieve a full REVO digitalization of the flexo process.”

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Marko Tiainen of UPM Raflatac comments: “The REVO Digital Flexo Revolution is setting a global standard, and this calls for consistency from all partners.  UPM Raflatac is an innovation-driven, front running developer of self-adhesive label materials, and our proprietary production technologies guarantee the same consistency of surface quality and ink reception in every corner of the world. Among the benefits of REVO are cost-efficiency and a reduction in waste, and our product development supports this with materials like those in our Fit range, which are engineered for a more sustainable use of resources, cost-efficiency and process-efficiency while retaining optimal performance. New substrates and printing technology are progressing in parallel with the same objectives.”

Daragh Whelan of Adare finally concludes: if you can measure it, you can control it, and if you can control it you can reproduce it and this is one of the many advantages Revo gives to the converter. Having digital control of all of our variables ensures Brand consistency and enables Adare to emulate pantone shades out of 7 colours. With REVO “digitally” optimized technologies we are quicker to market and have also reduced the minimum order quantity for laminated flexible packaging products to as little as 5 kilos. It is like having a digital press with flexo costs.”

REVO Digital Flexo Revolution uses new Software, Hardware, UV Flexo inks, digital plates, new generation anilox rollers, 7 colours separation, standardized substrates and digital automation on press exclusively provided by REVO Members: Adare, Du Pont, Apex, Esko, GIDUE, UPM Raflatac, Flint. REVO Team Members provide together an “off-the-shelf” solution to Labels and Packaging converters, with a defined protocol of consumables, software and hardware technologies, which allow from “day one” immediate production using a REVO “digitalized” flexo process.

REVO Digital Flexo Standards will be available to the entire flexo industry 6 months after the official presentation of the REVO Project. REVO Partners agree to promote an “industry move” of flexo towards the full digitalization of the process, and agree to share at a later stage all the standards and the protocols defined for the best performance of the REVO Digital Flexo Revolution. The REVO Project standards will be open to all the flexographic industry players, who are willing to share the REVO Digital Flexo objectives.

REVO Team Members suggest the following list of main advantages for companies joining the REVO Digital Flexo Revolution.

Cost reduction: less substrate, less inks, less time are wasted for colour matching in the press. 90-95% of PMS palette is reproduced with 7 fixed colours in the press. Less ink is needed to print solid colours as only vignettes are used to reproduce heavy solids. Less substrate is wasted during set-up in the press due to Digital Automation and more up-time of the press is achieved due to down-time reduction for colour matching, print and die-cutting cylinders change, press set-up, press inconsistency during production.

Consistency: most variables are digitalized during the whole “from pre-press to print” chain. PMS inks are substituted by 7 fixed colours, operators skills are not required for colour matching. UV flexo inks deliver consistent ink behaviour in the press. Anilox rollers and inks are optimized for consistent performances. Digital Automation on press greatly reduces the variables caused by operator’s skills.

Quality: 7 colours separation-extended colour gamut provide vibrant effects on pictures, more natural and realistic images. 80 lines per cm screen count become standard, taking flexo to a higher print quality level.

Digital flexibility: the same file can be printed on a Digital or a Digital Flexo press, with similar quality and costs. With extremely limited wastes and set-up times on the press, production flow can be similar to a Digital press, with frequent job changes, job interruptions, high flexibility in jobs planning.

Graphic flexibility: a single job can show a virtually unlimited number of PMS colours, without additional print stations: 7 print stations are sufficient. 2 or more jobs can be interlocked, for short-runs production needs, on the same web, even if with several and different PMS colours. Still, 7 colours are sufficient.

A REVO Open House, at GIDUE premises in Florence from 10th To 12th of June 2014 , will introduce the REVO Project to the Labels and Packaging market. Live demonstrations of the full REVO process will be performed, with the participation of all the REVO Team Members.

More information & registration is available online soon: www.revo-digitalflexo.com

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Advantages of Flexographic Printing

By Don Amato, Chicago Tag & Label

 

If your company does its fair share of printing, it’s essential to understand the technology and equipment behind flexography. In basic terms, this process of direct rotary printing involves a raised image impressed into a flexible relief surface that turns the picture out onto a variety of materials. The concept is similar to the early letterpress style devices, which essentially “stamped” images and typeface onto paper in the publication of newspapers and books.

The technology offers many benefits over other types of reproduction, and the advantages of flexographic printing can be more easily understood by reviewing the process. First, the plate must be created by one of three techniques involving molding, computer-guided laser etching, or exposure of polymer to ultra-violet light. Next, the mounting process takes place, whereby plates are installed upon a cylinder, which is then inserted into the press. Finally, the ink is applied to the plate via tiny cups that hold exact measurements of the liquid, which will ultimately be deposited upon the printing surface.

While this description of the technology and method of flexography is quite basic, it’s still easy to see the advantages of flexographic printing. From the plate-making to the mounting process to the transference of the image, flexography is as its name suggests: a versatile and adaptable means of handling large scale reproduction of images and text.

Flexographic printing offers a variety of ink types, many of which require little or no drying time. 

When letterpress technology was popular, companies had limited options for ink and printable surfaces. For the most part, ink was water-based and required a certain amount of time to dry to avoid smudging. Commercial dryers were eventually developed to facilitate the process, but at an additional cost for equipment and maintenance.

Today’s flexographic printing methods involve quick drying in a wide variety of ink types. Depending on the application and surface to be printed upon, you’ll have the choice of five different kinds. Solvent-based solutions are ideal for plastics, wallpaper and other commercial uses, while water-based inks work well for more porous materials like cardboard and paper. To reduce or eliminate drying time, electron beam or ultraviolet curing inks are popular when printing onto plastic and cellophane. Chemical curing inks typically require a two-step process, which makes them useful only for a limited number of applications.

Flexography enables printing on a wide variety of both porous and non-porous surfaces.

Companies are no longer limited to cardboard, paper and fabric when printing images, making this feature one of the top advantages of flexographic printing. Countless consumer and commercial goods involve this technology, from the printing of wallpaper to creating giftwrap to coloring floor tiles.

The easy plate-making process enables you to print millions of images with one template.

Whether using plastic or polymer, the plate created during the flexographic printing process is durable for a consistent image with every print. Every copy created is an exact replica of the previous one, and your first reproduction is the same as the last. You avoid the need to restructure the plate, thereby avoiding slight discrepancies that can cause image variance and irregularities.

Pre-established inking amounts throughout the printing process means there’s no need for adjustments or re-calculations in the middle of a job.

Problems with ink distribution can completely destroy a printing run, costing thousands of dollars when you need to start the process again with new materials. Exacting ink control is one of the best advantages of flexographic printing, and it’s typically handled by either a fountain roll system or doctor blade technology. The former involves pouring the designated ink onto cups or grooves on the plate, whereas the latter is more precise. A doctor blade system incorporates geometry and volume displacement to determine the amount of ink necessary to evenly cover the plate. Then, it essentially “squeegees” off any excess ink to ensure that the resulting print is clean and smudge-free.

Flexographic printing technology is capable of printing continuous patterns.

Reproducing images and text on corrugated cardboard, labels and other individual items isn’t too difficult for most current technology. However, there is more of a challenge when you need to print a constant pattern throughout several dozen or even hundreds of feet. Examples include wallpaper, printed cellophane and gift-wrapping, which require a seamless pattern in a continuous, unbroken design. The rotary operation and consistent ink control of flexographic printing enables you to print the same design over and over without interruptions in the pattern.

Flexography is ideal for solid color printing.

Due to its exacting ink control systems, one of the best advantages of flexographic printing is the ability to generate solid colors on both porous and non-porous substrates. In other printing processes, several layers of ink are required to attain the proper saturation and richness. Because the ink used in flexographic printing is able to dry quickly or cure without the need for drying time, several layers can be applied within a short amount of time.

For food-related consumer products, flexographic printing offers the perfect balance of durability and safety.

Certain governmental regulations require that food packaging containers be printed with ink that will not wear off, flake, separate or otherwise degrade. Added to this challenge is the fact that most food packaging is comprised of plastic, cellophane or other non-porous materials to which traditional inks won’t adhere. With flexography, printings are bonded to the surface without the threat of deterioration or safety risk to consumers.

When considering your printing options, it’s best to make your decision by balancing cost effectiveness, quality and versatility with the application for its intended use. There are certain advantages of flexographic printing that make the process well suited for many consumer and commercial applications. Its capabilities surpass traditional methods that don’t feature the same flexibility and technological advancement.

About the Author:

chicago-tag-don-amatoDon Amato is Vice-President, Sales of Chicago Tag & Label in Libertyville, IL. Chicago Tag & Label manufactures form labels, labels and tags that deliver solutions to a broad range of industries including retail, industrial, manufacturing, distribution and medical environments.

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How UV-LED Inkjet Technology is Increasing Profits for Flexographic Printers – Part 3

By Roland DGA 

Package Prototyping 101: Why Universities Have Adopted Roland VersaUV Technology 

Outside the business arena, VersaUV technology has found an enthusiastic audience within the university system, where the basics of the design, printing and finishing processes are taught to aspiring package designers.  Across the U.S., several of the most renowned package design schools have adopted VersaUV technology, citing its quality, efficiency and overall versatility as key factors in their selection process.  While these institutions often serve a range of student requirements and applications, having VersaUV in-house allows them to also explore design concepts on the vast range of substrates that flexo presses support.

Two such universities include the Sonoco Institute of Package Design & Graphics at Clemson University and Rochester Institute of Technology (RIT) School of Print Media.  For these and other institutions, VersaUV’s unique ability to print, score, die cut and emboss actual press substrates to exacting specifications makes it a great platform for both instructional and research purposes.

The Sonoco Institute of Package Design & Graphics at Clemson University

What makes packaging appealing to consumers? Why do certain colors, textures and graphics generate interest while others get passed over?  The Sonoco Institute of Package Design and Graphics at Clemson University in Clemson, S.C. exists to help answer questions like these.   Each year, its faculty instructs more than 200 students in the art of packaging design.

“Our students are interested in developing real packaging for real applications,” said Dr. R. Andrew Hurley, assistant professor at the Sunoco Institute of Packaging Design and Graphics. He and his students value the VersaUV for its ability to print on a wide range of substrates, creating prototypes that are virtually identical to full production packaging.  They have run projects on plastic bagging material, thermoformable substrates, corrugated cardboard, and several types of paperboard. “The Roland prints on virtually any material, so when our students designed flexo packaging, we rarely had to worry about substrates,” Hurley noted. “It was liberating knowing that our designs would come out perfectly on the final manufacturing material without having to print on roll stock, cut, glue, score and then have a smear or air bubbles. With the LEC-330, we were able to save time, money, materials and design according to our specifications, not to the limitations of our equipment.”

The Sonoco Institute of Package Design and Graphics is equipped with state-of-the-art facilities, including a cutting-edge prototyping lab.  Among the lab’s current high tech equipment is a Roland VersaUV LEJ-640 64-inch UV inkjet printer. Originally, an LEC-330 was being used for the program, but the Institute recently replaced that model with an LEJ-640 to be able to print on thicker stocks such as corrugated boards.

According to Hurley, students leverage the VersaUV’s capabilities to run multiple iterations and then determine what works best for their respective projects.

“The results are stunning” said Hurley. Using the VersaUV’s CYMK plus white and clear inks, students can reverse print with a basecoat of white ink, produce full-color images, and finish each project with unique patterns, textures and varnishing effects using layers of clear ink.  “Elaborate textures and effects like these would be very expensive to simulate on other equipment,” Hurley noted.

In addition to students, the university serves more than 600 corporations who have worked with the Institute’s faculty and staff to train their employees in digital design, as well as to take advantage of the Institute’s comprehensive packaging design and testing process. The design and testing process begins with faculty and students working collaboratively with corporations to develop specific packaging designs and prototypes.  Next, the Institute uses its own fully-stocked grocery store to test the effectiveness of the packaging.  Prototypes are placed next to competitors’ products in the store aisles.  Shoppers are given a list of products to purchase and are asked to wear eye-tracking glasses.

As shoppers make their selections, the inward- and outward-facing cameras on the glasses record the movement of their eyes, giving researchers a window into their cognitive process.

“Especially for the testing process, we rely on the VersaUV for its precision color matching and accurate registration to print realistic prototypes,” reports Hurley.  “I am completely amazed by this machine.  It fits in perfectly with our curriculum and allows the students to see the results of their work almost instantaneously.”

Rochester Institute of Technology’s School of Media Sciences

For RIT’s School of Media Sciences, VersaUV technology is equally important. The university is known for leveraging its state-of-the-art facilities to prepare graduates for careers in printing and publishing. RIT has been using a Roland VersaUV LEC-330, and the inclusion of this advanced 30-inch UV inkjet printer/cutter has helped to fill an important need in the school’s curriculum and research.

“The VersaUV has generated a lot of excitement among the staff and students. It raises the bar with multiple colors and surface effects,” said Erich Lehman, Premedia Facilities Coordinator, RIT School of Media Sciences. “The students have used it to turn out some really innovative work.”

At RIT, Lehman and his students have the opportunity to test out the latest in printing technology from a variety of manufacturers. Students use the VersaUV to produce a variety of graphics, including packaging prototypes.

“We find the VersaUV incredibly valuable for teaching concepts for flexographic applications,” Lehman said. “It prints on a wide variety of flexo substrates, and since it prints white ink, we are not limited to opaque substrates. The VersaUV gives us the ability to take a student’s flexo project from ideation to realization.”

RIT students often employ the VersaUV’s white and clear inks on their designs, creating gloss and texture. “The clear ink has been incredibly popular,” said Lehman. “Students enjoy using it to add texture and interest to their projects. They also enjoy experimenting with the wide variety of substrates that can be run on the LEC.”

Student packaging designs have earned top honors in the American Packaging Corp./Kraft Product Design Challenge at RIT. In the four-week challenge, students from the industrial and graphic design departments worked with packaging science students to create new packaging for familiar brands, including Planters Peanuts, Wheat Thins, Oreos and Nutter Butters. The teams’ formal presentations were judged by representatives from the sponsoring companies.

Professor Alex Lobos of the School of Industrial Design noted that having the VersaUV allowed the students to produce actual prototypes rather than appearance models. “This is a critical difference for the students as well as for the judges. The packages were created as designed, with nothing lost in translation,” said Lobos. He also credited the VersaUV with allowing the students to attain an additional level of understanding of the production process.

Download the entire paper.

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How UV-LED Inkjet Technology is Increasing Profits for Flexographic Printers – Part 2

By Roland DGA 

UV Printers in Action

To get a feel for how UV technology is revolutionizing pre-press and proofing, it helps to take a look at some real-world examples.  These companies are currently putting advanced UV-LED printers to work in their respective businesses to increase the efficiency, capabilities and overall success of their operations.

PBM Graphics, Inc.

Packaging Prototypes Increase Sales for North Carolina Printer
Durham, North Carolina-based PBM Graphics, an “A to Z” printing and fulfillment company that employs a staff of nearly 600 and has specialized in commercial printing for more than 30 years, operates under the umbrella of Consolidated Graphics – a 70-company business network generating $1 billion in annual sales. PBM, which runs multiple sheetfed and digital presses as well as a full web and flexo press, started producing packaging prototypes in late 2011 when it purchased a Roland VersaUV LEC-330 UV inkjet printer. Since then, the company has successfully grown its business by offering package prototype services.

PBM uses its VersaUV to produce prototypes of gift card carriers for many of the most recognized retailers, overwraps for trading card clients, and shrink wrap prototypes for bottle packagers and adhesive label packages.

“We originally purchased the VersaUV for its opaque white capabilities, but use it far more often for prototyping,” said Adam Geerts, President of PBM Graphics. “We really appreciate the LEC-330’s ability to produce textures, like simulated foil stamping and embossing, as well as the wide variety of substrates the printer can accommodate.”

Geerts points out the significance of PBM’s LEC-330 purchase. “Among all the millions of dollars of equipment we’ve purchased over the years, nothing has generated as much excitement with the sales team as the VersaUV LEC-330.  There’s a lot we can do to show the customer what a finished product will look like without having to manufacture one,” he said.

According to Geerts, the functionality and capabilities of the LEC-330 have allowed PBM to save a significant amount of money. “The foil stamping, embossing and printing plates made a lot of prototype projects cost prohibitive in the past,” Geerts said. “With our VersaUV, we’re now able to produce the same jobs that previously would have gone through full manufacturing for pennies on the dollar.”

Geerts also notes the importance of being able to create realistic prototypes affordably and in-house when it comes to acquiring new business. “A lot of what we do is done at our own expense to help a sales person get a foot in the door or to assist an agency in winning a campaign. It’s one thing to talk about an idea, but to be able to see and hold the concept is much more compelling,” he said.

“The VersaUV is the highest quality digital proofer that we’ve ever experienced,” said Geerts.  “We can get the resolution, color and textures needed to make accurate prototypes for any of our customers.”

K1 Packaging Group

VersaUV Allows California Printer to Fully Satisfy Existing Clients and Attract New Customers
Headquartered in City of Industry, Calif., K1 Packaging Group produces paperboard folding cartons, digital and flexo printed labels, and high-end graphic packaging materials for both domestic and international retail.  K1’s clients include companies within the food and beverage, beauty and cosmetic supply, media software/hardware, and nutriceutical and pharmaceutical industries.  In addition to their main 85,000 square-foot location, K1 has another 20,000 square-foot facility in Pomona, Calif. that houses Everest Packaging, which focuses on contract packaging.  Altogether, K1 employs a staff of 90 and a variety of devices, including Mark Andy, Inc. flexographic printers and a Roland VersaUV® LEC-330 UV-LED Printer/Cutter.

Jimmy Tsai, K1 Packaging Group’s sales manager, notes that the LEC-330’s ability to produce highly realistic prototypes, along with the printer’s unique embossing and spot UV capabilities, is what won them over. “Many of our customers’ projects are printed on holographic material. The fear of running a print job without first producing a sample is very high, with all that could go wrong and the costs involved if it does,” said Tsai.  The LEC-330 has eliminated that fear by enabling K1 to create prototypes that closely resemble the finished product.

According to Tsai, early concerns over the ROI his company would see from the LEC-330 purchase were quickly alleviated.  He notes that the investment has completely paid off, allowing K1 to bring in a new base of customers – primarily from the personal care and cosmetic industries – in need of package prototypes that look like the real thing.  In serving this higher-end clientele, K1 has also found the LEC-330’s ability to print white ink extremely useful for creating packaging that really pops and attracts consumers.

Tsai points out that his customers are thrilled with everything the LEC-330 can do. In addition to enabling K1 Packaging to create realistic prototypes efficiently and cost effectively, it has allowed the company to increase their relationships and become more involved with clients at an even earlier stage in the creative process.

White Graphics, Inc.

UV-LED Technology Enables Illinois Shop to Produce Realistic Flexible Packaging Prototypes
Employing a staff of nine at its Downers Grove, Illinois headquarters, White Graphics produces flexible packaging, displays, cartons, pressure sensitive labels, mockups and sales samples.  The company’s client list includes a number of corporations, such as M&M Mars, Unilever, PepsiCo, Sonoco, Handi-Foil and Packaging Corporation of America – all of which depend on White Graphics to provide them with high quality, innovative packaging solutions. To expand their production capabilities, White Graphics purchased a Roland VersaUV LEC-300 printer/cutter.  Following the success of the 300 model, a VersaUV LEJ-640 flatbed printer was recently added to the workflow. The ability to print on such a wide variety of substrates has made a major impact on the company’s success.

Richard White, president of White Graphics, appreciates the durability of Roland’s ECO-UV inks, especially when printing on foil bags and other flexible substrates.  “The inks have a lot of stretch to them so they don’t crack, yet the surface passes any rub test you can imagine,” he noted. “The ability to create very tight comps of flexible bags with white underlay, as well as the corresponding corrugated and folding carton pieces, has made us a valuable partner in product development for our clients.”

“Applying white underlay and ECO-UV Clear Coat overlay on foils in conjunction with full-color process creates an almost perfect comp as an end result,” added vice president Andrew White.

Because White Graphics produces packaging for the food industry, samples of their printed products are rigorously tested at sensory laboratories to check for any retained odors from the printing process. To comply with the testing procedures, White Graphics’ food packaging print samples are wrapped in aluminum foil as they emerge from the printer and sent directly to a laboratory. “The packages we printed on the VersaUV passed the lab test with an A+,” Andrew said.

Operating in a niche market that depends on their ability to turn around complex jobs quickly, White Graphics relies on the company’s ingenuity and the advanced functionality of its equipment to satisfy its existing clients and attract new customers. “There isn’t a job that comes in here that isn’t a challenge, said Andrew.  “The VersaUV quite simply allows us to provide better service to our clients.”

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How UV-LED Inkjet Technology is Increasing Profits for Flexographic Printers – Part 1

By Roland DGA

Having the ability to quickly create a realistic package prototype that impresses a potential client with its detail and accuracy can make all the difference in the world when it comes to winning business in today’s competitive marketplace.  Until recently, the problem has been how to easily and effectively achieve this level of realism – a prototype that closely matches the final product – cost effectively and within a short window of time. Using specialized proofing equipment or stopping the press to run samples can cause considerable inconvenience not to mention thousands of dollars of lost production revenue.  Today’s advanced digital UV inkjet printers and printer/cutters offer companies specializing in flexographic printing an effective, affordable, user-friendly solution.

How Digital UV Inkjet Printers are Revolutionizing the Pre-Press Process

Incorporating state-of-the-art technology, UV inkjets are capable of producing realistic package prototypes in hours instead of days or weeks, without the long set-up time, waste and returns associated with traditional package prototyping methods.  In addition to enabling flexo printers to create high quality prototypes in-house and in record time, the ability of UV devices to print on virtually any substrate allows for the creation of package prototypes using materials identical to those used in the final print run.  The advanced features of UV inkjet printers also make it possible to incorporate unique, eye-catching varnish and embossing effects that add value and appeal to any prototype. These innovative UV devices are opening up new profit centers as well, allowing flexographic printers to accept shorter runs and new types of print jobs that previously wouldn’t have been economically feasible.

By making it possible to create detailed, realistic prototypes without taking the press offline or outsourcing, a digital UV inkjet printer, such as those within Roland’s VersaUV® series, can save valuable time reducing both cost and labor. Because these machines are capable of printing directly onto the flexible substrates and clear films often used in flexo jobs – including PET, PP and shrink wrap – accurately matching colors and providing “proof of concept” becomes a much easier task.  A packaging design firm, flexo printer, or converter that adds a UV printer into its daily workflow can show a prospective customer a prototype that resembles the final, finished product in every respect – right down to the client’s desired packaging material – within hours.

Proofing

A big part of the pre-press process is proofing, which can be an expensive and painstaking process. In a flexo operation, even a single proof or comp requires creating plates, which adds labor and material cost to the job.  While many shops rely on water-based inkjet proofing devices to curb costs and produce proofs, these platforms don’t always support the types of films and other substrates used to produce flexible packaging.  And, prototypes produced on substrates differing from those used in the final product – even if those differences are subtle – can cause problems when the job goes to production.  The emergence of UV-LED inkjet printers addresses this dynamic.

These devices deliver both the precise color imaging of water-based inkjets and the broad media support needed to effectively simulate on-press results, at a fraction of the time and cost.

Distributed Print Operations

Employing a UV printer can also greatly enhance and expedite the pre-press process when more than one facility is involved.  Advanced color management software designed to interface with Roland’s VersaUV printers – including programs from GMG, CGS and EFI – dramatically improve color-matching accuracy and simplify the entire proofing/color verification process.  Working in conjunction with Roland’s advanced VersaUV printers, this software not only enables you to hit the exact color you’re looking for, it also ensures consistent results across pre-press and production platforms when printing takes place at multiple locations. For example, proofing can take place at a facility in the U.S., and you can expect the same results from printing presses, whether flexo, rotogravure, or lithographic, located anywhere in the world.

Finishing

Package designers and brand managers often wish to see a variety of packaging options that differentiate their products from competitors while capturing the look and feel of finished goods.  VersaUV printers and printer/cutters offer a variety of finishing options. Clear Coat ink offers the ability to add matte or gloss varnishing effects for highlights or floods that closely match the final printed product. You can even simulate embossing for brand names or special effects.

Finishing also includes die-cutting and scoring of the materials. A UV-LED printer featuring integrated contour cutting, such Roland’s LEC-330 and LEC-540, not only prints but also performs scoring, kiss cutting and die cutting functions all in one seamless workflow, assuring that the proof you review is truly representative of the final product.

Low Heat Curing

Although UV inkjet printing has been around for quite a while, until recently, it was limited by the nature of its curing technology.  Conventional UV lamps can reach temperatures as high as 1500°F (800°C), virtually eliminating the possibility of printing on any heat-sensitive material.  Today’s UV-LED lamps, generate very little heat, allowing them to print on a wide variety of films used in flexible packaging, including clear, metallic, colored and shrink.

Specialty Ink Benefits

In addition to printing CMYK, Roland’s VersaUV printers can also be equipped with specialty inks, including clear and white. The ability to print high opacity white ink is especially important for flexographic printers, since many flexo jobs involve printing on metallic, clear films and shrink wrap.  Roland’s ECO-UV® and ECO-UV® S inks dry instantly and are extremely durable, so they won’t rub off like other white inks. ECO-UV S ink can also be stretched and applied around curved surfaces and edges without peeling or cracking, making it ideal for shrink sleeves, shrink wrap and other vacuum forming and flexible packaging applications. Clear coat offers advantages, including an unprecedented high gloss finish on output, special varnishing and embossing effects, scratch and chemical resistance, and enhanced outdoor durability.  Digital UV inkjet printers that support specialty inks improve and expedite the proofing process, allowing you to get the highest degree of accuracy and assuring the success of your final press run.

Low Operating Costs

Low cost of operation is another UV-LED technology benefit.  In fact, the cost of producing a sample on a UV-LED device can be as low as a few cents per sample. Compare that to an estimated dollar-per-sample cost basis for the same proof generated on a water-based inkjet or $50 to $500 per sample when outsourced.  Running a press to produce proof samples is even more expensive. Plus, UV-LED inkjet proofs can be produced on demand – in one or two hours if needed – allowing design and production changes to be implemented in real time.

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Calibrating Eurostampa’s Flexo Methodology to G7® Standards Returns Big Dividends

lBy Salmon Creek Media & Marketing

Since 1966, Eurostampa, an Italian-owned company, has produced high-quality labels for the wines and spirits industry, including major international brands Bacardi, Smirnoff, Captain Morgan, Jim Beam, Wild Turkey, Skol Vodka, and Kahlua. In 2010, they broke ground on their new 70,000 square foot printing facility in Cincinnati, Ohio, headquarters for their North American operations.

siller-francisco“As a family owned, global company that is well-known for supplying the highest quality products and service to our customers, we are always looking for innovative ways of improving our processes to ensure that the products will be fit for purpose, with the leanest and fastest operations available,” explained Eurostampa’s Quality Manager Francisco Siller. “We were already qualified on G7® in offset when the decision was made to qualify as a G7® Master Printer for flexo. G7® for offset brought immediate benefits to our prepress operations that were immediately perceived by our customers, mainly for new projects.”

Beginning the G7 Qualification Process

To manage the process that would lead them to formal qualification as a G7 Master Printer by IDEAlliance, Eurostampa turned to All Printing Resources (APR). The role of the G7 Expert is to facilitate the implementation of the G7 process and submit documentation and samples to IDEAlliance on a company’s behalf.

“APR has been a reliable supplier of flexographic solutions for Eurostampa in North America, and their qualified flexo team is always willing to help Eurostampa on continuous-improvement initiatives,” said Siller. “As soon as we learned that they had G7 expertise in flexography, we decided to develop this project together.”
CatHaynes2Bringing a level of experience and a real understanding of the project’s challenges was APR’s Catherine Haynes, a Qualified G7 Expert, who worked closely with Ken Codling, Technical Manager; Bob Fenster, Production PSL Manager; and Francisco Siller. “It was a great experience working with her,” Siller continued. “She is a knowledgeable, ‘hands on,’ committed professional.”

As a neutral, objective observer, Haynes was able to work with the press operators and show them how the G7 qualification process gives them new tools to make their jobs easier. As with any new project, there is always some resistance; however, standardization and process improvement have always been a part of Eurostampa’s culture, and their press operators quickly realized the benefits the G7 process would deliver for their workflow.

Prior to starting G7 implementation, Eurostampa had great process control and was at a GRACoL 6 Standard, which made for a smooth qualification process. They have always been a company striving for operational excellence and measuring the critical variables of every process, and not just on press. This has been the key to the company’s success.

APR brought their own software for the qualification process, but their ultimate goal was to have Eurostampa be able to do it themselves with their own tools. Eurostampa did use their own RIP.

The G7 Qualification Process

The entire G7 qualification process entails:

  • Defining the goal
  • Running a gray-balance target
  • Measuring and analyzing the target
  • Applying the curves to the file
  • Running the gray-balanced plates
  • • Profiling the process

The first phase of the calibration process required linear press runs to benchmark where Eurostampa was and then develop the necessary adjustments curves. Calibration has a two-fold benefit. It brings a process into a known state, one defined by standards that direct us to a commonly agreed state of order. It also helps extend the life of the process, bringing it back to a known state of order—to the specs.

ES_G7Anal

The second phase involved rerunning the jobs with new adjustments. There was a third and final run to confirm the results.

The goal was to qualify three different substrates—metallized, paper, and film—within a three-day period. Everything was calibrated using Curve 3 software for curve adjustments and setting the definition of neutral gray. Calibrating each of these processes to a common, known state means that Eurostampa can now generate one proof because all of their processes share a similar neutral appearance.

For flexographic printing, the standards are still offset-based, so it can be difficult to get the flexo inks to match the target values. The standards are also based on paper and not film. “There were many variables involved,” noted Siller, “and the latest technologies were required. G7 can be more complicated for flexo than it is for offset. With less control of an ink’s density at the press, it limits the ability to achieve target densities. Note: There are flexo-based targets, but they are not presently part of IDEAlliance’s qualifications.

ES_InkTarget

The challenges of Flexo often make it difficult to become a flexo-qualified G7 Master Printer. While there were only 11 printers worldwide that had achieved the high expectations of IDEAlliance’s G7 Master program and were listed in the IDEAlliance G7 Master Database when Eurostampa completed the process in March 2013, Eurostampa easily qualified.

“Although a company only needs to qualify on one substrate,” said APR’s Catherine Haynes, “Eurostampa chose to run three different substrates, and all three passed.”

ES_NPDC

Now that the G7 qualification has been completed successfully, Eurostampa is educated about the process and enabled to continue applying this gray-balancing process for themselves. However, future G7 Master qualifications by IDEAlliance will require a submission process through a G7 Expert.

Using G7 process control is providing returns in improving quality and efficiencies at Eurostampa. Operators now have specific targets and the tools to help them manage the process, and there is no need to constantly tweak the press conditions.

While it isn’t easy to maintain G7 process control, Siller says that it is doable. “We need to keep current on software updates, target updates, and measuring equipment upgrades. It forces the verification of critical variables on every process before any project goes to the press, and it makes us ‘do it right the first time.’”

Eurostampa Realizes the Benefits of G7

G7 Master Printer status brings significant benefits to a company. Eurostampa has added verification steps, but decreased time lost at the presses for not having the right elements for production. They are seeing quality benefits including color consistency, better setup times, and reduced waste. And, their customers are now working with known standards throughout the prepress workflow, allowing them to achieve a common appearance across their product lines and reduce their costs and time to market.

About Eurostampa:

eurostampaEurostampa is a family owned company. In over 40 years of activity it has been able to stand out in all five continents in the world of quality and highly prestigious label printing. It has been able to offer a combination of traditional artwork, typical of what is made in Italy, and high technology using off-set, flexo, screen and digital printing. Right now, Industria Grafica Eurostampa has three different plants, the headquartersin Bene Vagienna (Italy), a second one in Cincinnati, Ohio (Eurostampa North America) and a third one in Glasgow (Eurostampa UK).

About All Printing Resources, Inc. (APR):

apr-logoAll Printing Resources, Inc. (APR) is a proven resource for solutions, trusted service, and support to the flexographic printing industry. APR delivers measurable performance enhancements and total cost reductions, including the after sale attention needed to see optimal results. APR represents some of the most innovative product lines worldwide and takes a “team” approach to deliver process improvement and innovative solutions.

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Understanding Common Flexo Print Defects – Part 3

 

In this article, we revisit an earlier article from 2009, Trouble shooting “Ink Spitting”, originally written by Tim Reece, this version includes updates by Catherine Haynes.

UV Ink Spitting

While UV inks continue to increase in popularity over water-based and solvent-based inks due to their outstanding print results, especially in the narrow-web arena, the issues with UV ink spitting seem to persist. In 2009, APR published a Tech Tip article on this very topic and in many regards the industry has not made much more progress toward resolving the issue since then. Many of the same thoughts regarding why it happens and the techniques for trouble-shooting ink spitting are still being pursued.

In 2009 we cited the ink viscosity as being the most common explanation for why UV inks spit, where the problem is basically non-existent with water-based and solvent-based inks. The theory is that due to the inherently viscous nature of UV inks (being as much as five times that of other ink types) within the transfer zone of the press, high hydraulic forces are being applied to the doctor blade. The thicker UV ink creates a hydroplaning effect that actually lifts the doctor blade a very small amount and causes “extra” ink to come through under that portion of the blade and transfer to the plate. This excessive ink then prematurely releases from the plate, especially at higher press speeds, and results in what can be a very troublesome print defect. It has also been reported that contamination in the ink or if the ink wasn’t ground properly and small amounts of pigment migrate underneath the doctor blade, this can create the opportunity for poor blade metering and an uneven ink film thus leading to potential ink spitting.

These images from Daetwyler illustrate this hydroplaning effect. The stiffer, re-enforced, blade (on the right) is able to better and more consistently meter the ink.

nother possible contributor is the thixotropic properties of the ink. Thixotropic fluids decrease in viscosity over time at a constant shear rate. As UV inks are released from the anilox roll, metered by the doctor blade, and finally transferred to the plate the ink becomes thinner and more likely to spray or spit. Another way to understand this is to think of ketchup (also a thixotropic fluid) in a bottle (a loose correlation I know, but bear with me). Consider this scenario, you have just opened a brand new bottle of ketchup. You turn the bottle over to pour out the ketchup and [not so surprisingly] nothing happens. So you hit the bottle on your palm a couple times (to agitate it). If your timing, bottle tilt angle and agitation are just right, the ketchup gradually flows out and you continue eating your fries happily. However, if you over agitate, hold the bottle at too steep an angle and/or hold the bottle upside down for too long, ketchup uncontrollably “spits” or spews from the bottle, thus ruining your fries. So the question begs how to control this “thinning” of the ink on press. A technique much easier to master with the pouring of ketchup, though I suspect the current squeeze bottle was designed to combat this very issue and thus satisfy the American hunger for condiments.

The key is to reduce the risk of ink spitting without compromising print results. One variable that continues to prove as a key control point for minimizing ink spitting is the doctor blade and metering set up. Pressroom testing has proven that using a thicker blade minimizes UV spitting as the stronger blade better resists the hydroplaning affect and does not allow too much ink to transfer to the anilox roll. However, too thick a blade can contribute to an uneven film thickness that will affect process dots, reverses, small positive type, and bar codes.

While many companies have found ways to minimize the problem such as using a “backer” blade (to back up your doctor blade with another blade), leading blade suppliers have attacked this spitting phenomenon by focusing on specific characteristics of the doctor blade composition. Doctor blade manufacturers such as Esterlam and Daetwyler have developed special materials and blade configurations designed to remain stiffer yet still meter ink uniformly to substantially decrease UV spitting without compromising print results. These specialty doctor blades have been precision-engineered to be thicker at the base (where the blade is installed in the holder) and extend close to the contact metering point but with tips designed to maintain the quality and characteristics of a standard edge. These blades’ unique designs allow the thicker ink to meter itself just like it would with a normal doctor blade, but because of the blade’s strengthened base, the amount of flex is decreased. Consistent ink-film metering is therefore accomplished while avoiding ink hydroplaning of the blade, substantially lessening UV spitting.

Example Blades for Ink Splitting

Long-Life Blade

 One-Step Blade

Images from Daetwyler

It is also important to have the blade metering at the correct angle to ensure an even, consistent wipe. The press ink chamber or ink metering system is designed so the blade makes contact with the anilox at the appropriate metering angle. Usually the target is about a 30° angle. For an enclosed doctor blade chamber this is already set at a predetermined angle. For a reverse-angle doctor blade a 30-35° range is recommended.

Ultimately the operator should set the blade angle to ensure metering is optimized for the given metering system, anilox cylinder and ink type. A general rule of thumb, the steeper the metering angle, the more ink is wiped from the anilox, thus reducing the ink film thickness transferred to the plate. A steeper angle also requires less blade impression, which should improve blade life and reduce anilox wear. So a slightly steeper angle may be optimal for process color printing, while a more shallow angle may help solids and coatings with a thicker ink film thickness.

It is the operators responsiblility to ensure the proper blade is being used, the blade is seated correctly (flat and evenly in the blade holder) and the appropriate amount of impression is applied to sufficiently meter the ink without causing blade lift or damage. A simple visual inspection of the anilox roll as it is being metered is a good way to identify that proper and even impression has been applied. As the blade impression is increased, the anilox should change from a shiny to a more-desirable, dull appearance. Of course, the blade wears throughout the run, so it is something the press operator must consistently monitor and adjust as needed.

For a more indepth explanation, check out this link: UglyFlexo: Doctor Blade Angle & Pressure. I would caution though, that trouble-shooting the blade is still not likely getting to the root cause of the problem. Of course you should optimize the blade specification, set-up and impression regardless of your battles with ink spitting, as this would impact many other factors of the process to include production efficiencies and print quality. If indeed, blade optimization is just a bandage to the problem, then eventually spitting will rear its ugly head once more.

Example of a Chambered Doctor Blade System

Image from Daetwyler

Now, lets go back to the theory on viscosity. In 2009, conventional wisdom maintained that ink viscosity was an essential factor to consider when faced with ink spitting. I am sure we would all still agree that viscosity is definitely one of the most important variables to ensuring consistent, quality ink release and laydown. It has a direct impact on color, final printability and drying, but does viscosity itself cause ink spitting?

In 2012, an FQC UV Ink Spitting report was published in the February issue of FLEXO. This FQC committee had been formed with the intent to conduct a study to test those variables that have been, for years, commonly attributed to potential causes of ink spitting. The members consisted of representatives from leading ink, anilox and doctor blade manufactures as well as other printers and suppliers to the industry. Multiple press trials were conducted under optimized print conditions in an effort to eliminate the potential influences (from controlled variables) and test the impact of seven independent variables. They specifically analyzed anilox cell volume, press speed, blade pressure, blade width, blade tip, blade material and viscosity. While you can reference this article for a complete summary on their study, what I found most informative was the report from the statisticians.

FQC Ink Spitting Report: FLEXO, February 2012

Read the entire original article here.

Ultimately, what we can draw from the 2011 FQC Ink Spitting study is that these variables do have an impact on ink spitting an can certainly be influenced to help lessen or postpone the resulting ink spitting; however, there still does not seem to be a clear correlation of cause and effect with any single variable or combination of variables. Looking at ink viscosity specifically, in all their tests, as viscosity was increased there was no consistent increase to the occurrence or amount of ink spitting. It really depended on the trial. Whether ink spitting did or did not occur, it could not solely be attributed to an increase in ink viscosity.

What does this mean exactly? It means that additional exploration is required to better understand what the unknown causes could be. Based on the findings presented in this article and the feedback from the statisticians that helped assess the FQC results, it seems there is something more going on here than can be attributed to the ink viscosity, cell volume, doctor blade specs and settings or press speed. It may have more to do with something inherent to the UV ink chemistry itself. While UV inks are traditionally considered to be low-maintenance, perhaps they are more fragile than we really understand. If the process or conditions in the pressroom lead to a contamination of the ink due to light, heat and/or lack of oxygen inhibition, there is a potential to prematurely begin the curing process. Could this be a possible root cause that then translates into the gradual accumulation of ink spitting throughout the press run?

For APR’s part, we will continue to monitor this topic and we welcome insight from those of you battling this problem today. Meanwhile, UV ink printers are continuing to make tremendous strides in printing high-quality graphics. Regardless of its impact on ink spitting, having the correct doctor blade and doctor blade set up are obviously key factors in achieving consistent high-quality print and increasing productivity. (And, it may very well alleviate ink spitting issues.) It is also essential to maintain close collaboration with your ink, anilox and doctor blade suppliers as they too endeavor to tackle this issue and devise new solutions or processes to resolve UV ink spitting.

Special thanks to Gallus for supplying some images for this article.

APR Technical Solutions Group

We have formed our Technical Solutions Group to encompass our full range of expertise in all critical areas of the flexo process. This team is made up of industry professionals dedicated to being up to date on new technologies, armed with the last in diagnostic tools, and experienced in problem solving that can achieve sustainable results. The TSG have walked in your shoes, and has felt your pain. For any specific questions please feel free to contact me at 847-922-0134 or tsg@teamflexo.com

For more information, call us at 1-800-445-4017.

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Unambiguous Conclusions of the EFlo Extended Cell Shape Performance

Testing the EFlo Extended Cell Shape V1.3
by Wilbert Streetfland, Technology Coating

 

Introduction

Pamarco contacted Technology Coaching (Wilbert Streefland) in 2012 for comparable testing of the EFlo extended cell shape. They wanted the tests carried out by an independent observer in unambiguous terms. Wilbert’s first comment to Pamarco was that they have to realise that tests will show what they need to know and that this often significantly deviates from what they want to hear about their product. They accepted this objective testing and we started the project.

When doing comparable testing we measure the level difference from properties that are important for the print process.

What are the key screen roll properties that have an impact on the print process?

  • Its ability to release ink;
  • Its ability to transfer a uniform and constant ink film to the print plate;
  • Cleaning intervals needed for maintaining the ink transfer level.

What is EFlo extended cell shape?

Let’s first look at the EFlo extended cell shape relative to the hexagonal cell shape. The following two images show side by side the EFlo and hexagonal cell shapes:

EFlo Extended Cell

Conventional 60° Hexagonal

Notice the stretching of the cells

Comparable testing of the screen rolls can in this case be done based on line count and/or on the number of cells/area. We did both.

Comparable testing

To do the comparable testing 2 identical banded screen rolls were produced.

Why use two screen rolls for the test?

The testing should be comparable to day to day printing which means also investigating wet in wet printing. A single colour banded screen roll test will never provide any information about ink trapping.

Test variables:

  • 2 identical banded screen rolls
  • 3 substrates
  • 1 ink (Colours: Cyan, Magenta and Black)
  • 2 printing speeds

The following table shows the configuration of the 2 identical rolls:

In total each screen roll had 14 bands. The bands A and B were engraved on the operator side and drive side of the roll. This was done for measuring machine alignment. You can’t judge the results of a banded screen roll test if the alignment of the machine is not monitored and equal on both sides. Thus on each side the results of the A and B bands were measured and compared.

The test form used for the test was specially designed and contained:

  • Large full tone areas including a large full tone trapping area
  • Barcodes with bars in print direction and cross print direction
  • Halftone areas with line counts up to 64 l/cm
  • Half tone areas with angles of 30°, 45 ° and 60° to investigate Moiré between print plate and screen roll
  • A special dot size area to investigate the minimum printable dot size where the target dot size on the print plate ranged from 20 to 150 µm for a coverage between 1 and 20%
  • Standard pressure marks

Conducting the test on a corrugated post printer allows testing a large variety of substrates in respect of ink absorbance. In this case we had coated white top liner, uncoated kraft liner and brown kraft liner.

The machine used for the test was the Bobst Masterflex HD installed at Ghelfi Ondulati (Italy). An excellent factory and machine for testing. It is important that a test is carried out according the preset protocol. Deviations from the test protocol are not allowed. This kind of testing can only be done when operators know what they are doing and the machine is in perfect working condition.

For this kind of testing the time used ratio for: Preparing the test : the actual test : the data collection and reporting is 4 : 1 : 12. The actual testing on the machine was about 6 hours. We did 10 test runs.

What was part of the evaluation?

  • Screen roll IFT (Ink Film Thickness on the screen roll surface);
  • Screen roll cell wall thickness;
  • Screen roll line count;
  • Colour variation;
  • Colour change during start-up;
  • Ink transfer;
  • Moiré between screen roll and print plate;
  • Dot size;
  • Filling of halftone area;
  • Trapping;
  • Barcode bar width gain variation.

Overview of the amount of data collected:

  • 7,600 spectral readings
  • 1,600 barcode scans
  • 540 microscope images
  • 84 image scans

Let us now look at brief results of the tests.

First the engraved rolls were measured and target compared with actual. This was done by allocating each band to 3 groups:

  • EFlo standard line count
  • Conventional 60° Hexagonal
  • EFlo high line count

The following image shows the relation between Line Count and Ink Film Thickness (IFT) on the roll surface:

Target

Actual

The actual measured results for IFT (Ink Film Thickness) and line count are in line with the target. This allows comparable testing. There are only minor differences between the 2 banded screen rolls, within normal tolerance.

Included in the test was also evaluation of Moiré patterns between screen roll and print plate. The tests showed that there was no difference in Moiré appearance between using EFlo and Hexagonal 60°.

Let’s now look at the result when printing cyan on coated liner. The following graph shows the relation between the “L” value of the L, a, b values measured using a spectrophotometer and the IFT on the screen roll. The “L” represents a value for the “Colour strength.” A higher L value means a lighter colour. Remember the colour will be lighter when the IFT (Ink Film Thickness) reduces on the roll surface but also when less ink is transferred from the roll to the substrate.

The graph shows an overlap for the Hexagonal bands and the EFlo high line count. We can conclude that the EFlo bands, having the same IFT and line count as the Hexagonal bands, transfer more ink. Ink transfer between EFlo and Hexagonal are equal when we have the same number of cells per area. The difference is smaller at low IFT on the surface of the screen roll.

Let’s compare bar width gain of the barcodes that were printed using black ink in function of the IFT of the screen roll bands:

Also here we see how the “EFlo standard” separates by having a higher bar width gain. This is logical because the “EFlo standard” transfers more ink from the surface of the screen roll.

Conclusions

The banded screen roll tests show:

  • A Pamarco EFlo Extended Cell screen roll with the same line count compared to a Hexagonal screen roll transfers more ink from the cells when both rolls have the same Ink Film Thickness on the surface of the roll;
  • A Pamarco EFlo Extended Cell screen roll that has about 1.55 times the line count of an Hexagonal roll transfers about the same amount of ink when both rolls have the same “Ink Film Thickness” on the surface of the roll;
  • Increasing line count with the same IFT on the surface of a screen roll results in a lower ink transfer ⇒ this results in the risk of the screen roll getting dirty more easily;
  • The dominating factor for dot gain is the amount of ink transferred. Thus when ink transfer reduces e.g. due to the screen roll getting dirty, not only does the colour shade get lighter but also the printed dots get smaller;
  • Using the Pamarco EFlo Extended Cell shape provides an opportunity in having a more stable ink transfer at equal line count compared to a conventional 60° Hexagonal cell shape, resulting in less stops during production.

The specification and selection of an EFlo Extended Cell shape screen roll as well as its behaviour is predictable relative to a 60° Hexagonal cell shape screen roll.
Thus potential customers can reliably change from the conventional Hexagonal screen roll to an EFlo Extended Cell screen roll.

Recommendations

Use 3 general screen roll specifications:

  • • Uncoated paper: IFT 10-12 μm, 100 L/cm (EFlo 160 L/cm)
  • • Coated paper: IFT 4-5 μm, • Process colours on coated liner: IFT 3 μm,

Please feel free to contact us for the full test report carried out by Technology Coaching BvbA.

Please do not hesitate to contact me if any questions.

Kind Regards,
Wilbert Streefland
wilbert@tcbvba.be

©Technology Coaching BvbA 2013

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Understanding Common Flexo Print Defects – Part 2

Dirty Prints

 

 

by Catherine Green, Technical Services Group
All Printing Resources

Introduction

Dirty print is a bothersome printing defect that stems from a wide array of potential causes. From the pressroom to prepress and platemaking, there are many factors that may contribute to this defect. As higher printing resolutions are demanded of flexographic printers, it is imperative that the process itself is capable of handling the demand to reduce the risk of dirty printing. In this article, we will explore some common causes and remedies for dirty printing.

Anilox Roll Selection

Selecting the proper anilox can be key in reducing dirty print in many situations. Most anilox roll manufacturers will recommend running an anilox roll with an LPI at least 5 times the printing LPI. This will prevent the smallest printing dots on the plate from being able to enter the anilox cell openings, avoiding “dot dipping” – a printing defect where small highlight dots dip into the anilox cells, collecting ink on the surface and shoulder of the dot (fig.1). This excess ink can transfer to the substrate causing excessive highlight gain and/or dot bridging, and also promote ink to further collect in the screened area on the plate.

fig.1   (illustration courtesy of Harper Corporation of America)

Also, selecting an anilox roll with the appropriate LPI and volume for your specific application will prevent excess ink from being delivered to the plate and substrate, minimizing the chances for dirty print related to the anilox roll. The best way to optimize and gain knowledge about your specific condition is to perform a banded anilox test. This test utilizes a specially engraved anilox roll with multiple LPI and volume settings, allowing multiple conditions to be tested simultaneously on a single print deck (fig.2).

fig.2   (illustration courtesy of Harper Corporation of America)

Accurate metering of the anilox roll by the doctor blade is also critical to consistent ink delivery. Operators should regularly check the doctor blade(s) for correct pressure, angle, and wear. Simply put, if too much ink is delivered to the plate, the ink can collect on the plate surface resulting in excessive gain in highlights, dot bridging, and loss of detail in fine type.

The Printing Plate

Proper image formation on the plate is key to maintaining clean, sharp graphic reproduction on press. This is especially important for highlight dots and fine type, which can be susceptible to instability and incomplete formation if the platemaking conditions are not properly optimized.

For screened highlight dots and small details to properly form and hold on the plate, it is imperative that the proper back exposure time is used to obtain a relief depth that is appropriate for the type of work being printed (fig.3). This will ensure that, with the proper face exposure, the dots have a stable base to prevent them from folding over under pressure. If this happens, the shoulder of the dot will print instead of the top, causing dirty print and massive gain in critical highlight areas.

Plate Thickness Recommended
Relief Depth
(high detail/process)
Recommended
Relief Depth
(low detail/line)
0.030″ (0.76mm)
0.045″ (1.14mm)
0.021″ 0.025″
0.067″ (1.70mm) 0.023″ 0.027″
0.100″ (2.54mm)
0.112″ (2.84mm)
– and up -
0.030″ 0.045″

fig.3

 In addition to relief depth, the plate’s overall stability and printability in a particular system can greatly affect the print quality. A common contributor to dirty print in the pressroom is plate swelling related to incompatible or aggressive inks. This defect can become most evident in screened areas where surface area is highest. To avoid problems on press related to plate swelling, it is always a good idea to perform a swell test with your intended plate and ink combination ahead of time to confirm they are compatible.

Another type of plate swelling can occur before the plate even reached the pressroom: insufficient drying of a solvent processed plate. Due to the fact that solvent plates absorb their processing solution during the washout phase, the plates will swell to a thicker gauge than intended for the finished plate. Drying the plate for the manufacturer’s full-recommended time at the specified temperature is a must if plates are to return to their intended gauge for press. Cutting the drying time short (yes, even a little bit) can negatively affect your print results.

Ink pH and Viscosity

Dirty printing is a common side effect when pH and viscosity are not carefully controlled with water-based inks (viscosity only with solvent-based inks). The viscosity of the ink can greatly affect the ink release from both the anilox roll and the plate. When ink becomes too viscous (too thick) it can load up more easily onto the plate, causing dot bridging and fill-in of fine type. Also, when the plate picks up a heavier ink film, it can cause higher than normal densities, trapping issues, and potentially slow drying.

The order in which the pH and viscosity are checked is also vital to success. pH must be adjusted prior to viscosity, as changing the pH will always change the viscosity, but changing the viscosity can be done without effecting pH (only use additives recommended by the ink manufacturer).

Ink Drying

The dryers could easily be one of the most commonly overlooked areas on the press. They play a huge role in the printability of inks and even plates. If not carefully controlled and inspected, the dryers can become out of balance, causing ink to dry on the plates or to not dry properly between stations, both causing dirty print defects.

Ambient temperature and humidity also affect the printing inks. For example, with water based inks, the amines can begin to evaporate more quickly at temperatures around 85 degrees Fahrenheit, causing the ink to become less viscous, dry poorly, and potentially build up around the doctor blades. It is best to maintain the pressroom near 72 degrees Fahrenheit and 50% humidity if possible, to reduce the risk of climate related dirty printing.

Dust and Web Contaminants

Keeping dust levels low in the pressroom and plate room can be a tricky task. With so many pieces of equipment cutting paper and creating static electricity, fighting dust can be an ongoing battle. The defects caused by these contaminants can be anything from small voids in solid areas where particles blocked the ink transfer onto the substrate, to a plate loading up with ink and printing dirty due to picking up excessive lint and dust.

Controlling lint and dust in the pressroom should begin with the ventilation system. Enough air should circulate to keep the majority of the dust at bay. If this is not the case, specialty systems can be placed to help with dust removal and air cleaning (for example, the Duster 2000). Also, web cleaners can remove contaminates as the web enters the press, before the lint and dust has a chance to contact the printing plate. The best answer is a combination of these solutions to minimize dust as a potential contributor to dirty print.

A Note About How Prepress Graphics Can Contribute To Dirty Print…

Catherine Haynes, APR Southeast Technical Manager 

Printers are continuously being challenged by their competitors and customers to achieve finer vignettes that can fade to 0% and print ever-higher line screens, and our industry has made great strides to do so. Vendors have devised a variety of solutions to make this possible – presses that print with much tighter tolerances, prepress software and equipment solutions that maximize the graphics potential and plate making options that allow us to take advantage of both digital and flat top dot benefits just to name a few.

However, smaller dots and finer vignettes also make all the previous contributors to dirty print mentioned earlier even more challenging. It is also important to note that the graphics themselves, if not managed correctly, can translate into what appears as dirty print. A good example of this is when the highlight portion of a vignette does not fade properly resulting in random or isolated dots that are not properly supported and thus print “dirty”. A similar effect can be seen in highlight areas of images where “scum dots” appear or hard edges are formed. Fortunately there are processes, tools and screening solutions available to minimize the effects – the key is optimization.


APR Technical Solutions Group

We have formed our Technical Solutions Group to encompass our full range of expertise in all critical areas of the flexo process. This team is made up of industry professionals dedicated to being up to date on new technologies, armed with the last in diagnostic tools, and experienced in problem solving that can achieve sustainable results. The TSG have walked in your shoes, and has felt your pain. For any specific questions please feel free to contact me at 847-922-0134 or tsg@teamflexo.com

For more information, call us at 1-800-445-4017, or fill out the Information Request Form.

 

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Understanding Common Flexo Print Defects – Part 1

Ghosting                               

 

by Tim Reece, APR Tech Services Group

Over the years, APR has shared many articles that assist in identifying and reacting to print defects such as dirty print, ink spitting, and ghosting. But as technology, equipment, and operating techniques develop, we find it necessary to revisit these areas of concern that continue to challenge many of us on a daily basis.

As I look back and think about my experiences with certain pressroom challenges I often remember the first time and place I was faced with a particular challenge. As I trained as a young press operator in 1982, my only exposure to a flexo inking system was a four-roll inking system. The press had a metering roll partially submerged in the ink pan, which transferred the ink to an anilox roll; and from what I recall there was never a shortage of ink delivered from plate to substrate. But then again, who knows…I’d never heard of solid ink density and the term “ghosting” had no meaning to me whatsoever. But also introduced to flexo in the 1980s was a component now commonly known as the (ECDB) enclosed doctor blade system. This unit can be credited with contributing to both better print quality, higher press speeds, and reducing ink consumption. It was also with my introduction to this new component that I had my first experience with ghosting. In Part 1 of this series our primary focus will be on “ghosting.”

What is Ghosting?

The flexographic term “ghosting” is actually borrowed from the offset printing industry. Mechanical pinholing is the print defect that we have adopted the term ghosting for in flexo. However, it does seem that most of us are in agreement that “ghosting” can be described as a faint image, which is repeated from another part of the design and appears in an area where it is not intended to be in the flexo print process. This type of ghosting is always found in the image area on the printed side of the substrate and most noticeably in large solid areas. Ghosting became more common after the advent of chambered doctor blades.

What Causes Ghosting?

In most cases ghosting occurs when the anilox roll cannot recover enough ink to consistently provide the required ink density. Ghosting problems are not necessarily more prevalent in darker colors, but they are certainly more apparent in darker colors like browns, reds, blues, and greens. The idea behind eliminating or reducing ghosting is to improve the ability of the anilox cells to both fill with and transfer ink.

Giving Up The Ghost

Both the porosity of an anilox roll’s cell walls and the cell depth greatly affect the transfer of ink to the substrate. As press speeds increase, the ability to consistently and effectively fill the cells on the anilox with ink in order to deliver a uniform ink film thickness to the plate becomes more challenging. The cell depth-to-opening ratio is of critical importance. Deeper cells may mean greater volume. However, if the surface tension of the printing plate is too low to pull the like particles of ink from the cell, then transfer will be very poor and ghosting may occur. Likewise, if the surface tension of the anilox roll is too high, it may easily pick up the ink from the fountain roll or the chamber, but not release ink from the cells resulting in ghosting. Because of the anilox roll surface topology, it is nearly impossible to accurately measure the surface energy or dyne. However, it is possible to test the transfer rates of printing plates with a large dyne range. In addition, proper ink viscosity is also important in reducing ghosting whether you are using solvent, UV or water-based inks.

Possible steps to minimize ghosting problems include:

  • On colors where ghosting is occurring, change the anilox roll to one with the same cell volume but with a coarser screen. This will bring the same amount of ink to the plate but with reduced ink drying on the anilox as long as the ink transfer rate is comparable.
  • With solvent inks and sometimes water-based ink, the viscosity may be too low. A higher viscosity should slow ink drying on the anilox rolls.
  • Because the defect is normally seen in large solids with reverse print or windows, you will sometimes have an overprinting white (reverse print on clear substrate). In this case the white can re-wet the ink that the ghosting occurs. So speeding up the white ink could yield favorable results.
  • If possible, put ghosting color on a back deck to utilize the full chamber for wetting.
  • Make sure the anilox is covered and protected from ambient air or air blown from the BC (between color) dryers.
  • Reduce blade pressure, which will reduce friction and heat at the sheer point of the ink.
  • Some enclosed chamber systems utilize an isometric inner cavity contour that through the use of fluid dynamics fill each cell with ink, and remove the air from the unfilled cells returning it to the feed tank for dispersal into the atmosphere. This process helps prevent ghosting and starvation from occurring, due to air pockets or foam build-up in the ink.
  • If possible, try to increase the dwell time between blades or run trouble inks on decks that have enclosed systems with greater openings. This will assist in the rewetting of ink on the anilox roll. A deeper chamber cavity will also reduce agitation inside the chamber, minimizing air pockets that could result in either ink starvation or ghosting. An analogy that always comes to mind is that Lake Erie is both the shallowest and most turbulent of all the Great Lakes, whereas Lake Superior is the deepest and calmest.
  • Severe ghosting can sometimes be reduced by adding extender or using a solution of 10% normal propyl acetate/90% ethyl alcohol.
  • While never the most popular action to take in a production environment, reducing the press speed can also reduce this effect.
  • Another solution, while not very practical, would be using a specialized anilox roll for a problematic job. If the anilox roll is the same diameter as the print cylinder, or at least a factor of the print repeat, it will synchronize with the design and ghosting will not appear. This would mean the cfd (complete finished diameter) of the anilox would be the same or a factor of the cfd of the print cylinder/print sleeve (consisting of bare cylinder diameter + the sandwich, i.e. mounting tape, plate, and possibly sleeve).

Other Potential Causes

Another phenomenon, which can be mistaken as ghosting or even ink setoff, can occur when running a 100% lacquer coat in the last-down deck, especially on paper substrates. Ink setoff occurs as ink transfers to the reverse side of the substrate on top of the printed image. Often the lacquer roller impression is hitting too hard, so it picks the printed image and duplicates this image. Unlike true ghosting, this can occur in either the printed or non-print area of the printed side of the substrate. This is often caused by four things:

  1. The operator has over impression on the rubber roller.
  2. The rubber roller has low spots and needs to be reground or replaced with a new one.
  3. The viscosity is way too high causing the over lacquer to be tacky and “pick“ the image, thus duplicating it.
  4. The print cylinder gear is the wrong size.

APR Technical Solutions Group

We have formed our Technical Solutions Group to encompass our full range of expertise in all critical areas of the flexo process. This team is made up of industry professionals dedicated to being up to date on new technologies, armed with the last in diagnostic tools, and experienced in problem solving that can achieve sustainable results. The TSG have walked in your shoes, and has felt your pain. For any specific questions please feel free to contact me at 847-922-0134 or treece@teamflexo.com.

For more information, call us at 1-800-445-4017, or fill out the Information Request Form.

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