The best plate technology and the newest state-of-the-art flexo press, along with multiple other consumables, will not amount to much if the plates are mounted incorrectly. Improper plate mounting leads to a loss in quality, downtime, and additional start-up waste associated with substrates, inks, energy, etc.
As Trendelina Kryeziu, marketing communications manager at Flint Group, states, “Plate mounting is a very straight-forward process.” It does have tremendous ramifications on the final printed image, though.
“Basically, if all the plates in a set are not mounted accurately it will be impossible to achieve good print results on the press,” says David Muncaster, director at JM Heaford. “Even the most sophisticated printing presses can’t print good quality if there is any skew between plates. If plates are mounted incorrectly, then the cylinders must be removed from the press and re-mounted.”
“Misregistration, blurry images, color inconsistency on multiple images, poor quality, and the potential of rejection at the end user due to visual quality deficiencies are all possible results of improper plate mounting,” explains Bill Enright, senior applications engineer at Mark Andy.
Enright, affectionately known as Dr. Flexo, cites a host of supplies necessary to properly mount plates. These include a cutting apparatus, ruler, squeegee and brayer, cleant lint-free towels, isopropyl alcohol, the plate mounter, mounting tapes, adhesion promotors and edge sealing tapes.
“Properly and accurately mounted plates, while making the right mounting tape selection based on the printing plate durometer, as well as the selected substrate, will have much more impact on print quality than most converters realize,” adds Enright. “If a converter striving for the best obtainable printed quality hasn’t recently conducted their own trials of plate and tape combinations to optimize their process, I strongly suggest they invest in the time to do so.”
The plate goes a long way in this process, as well. Converters would be best served to converse with their plate and tape suppliers to perfect this process for their unique printing environment. “Optimizing the plate technology with the correct mounting tape is critical to print performance and image quality,” explains Ronnie Scogin, applications development specialist at MacDermid Graphics Solutions. “It’s important to understand that the durometer of the plate shifts as the plate gets thinner because there is less material and more influence from the polyester backing. The effective durometer is also influenced by the mounting tape.”
When dealing with mounting tapes, Avery Dennison’s products offer repositionability and lower adhesive residue, which limits the amount of time press operators need to spend on cleanup.
“There are many advantages to using Avery Dennison tapes because the print quality is enhanced using a high-performance tape,” says Chris Blackwell, product manager, Print and Packaging, at Avery Dennison Performance Tapes. “Repositionability helps when the tape goes on incorrectly, allowing a user to pull the tape off the cylinder, reposition and reapply it correctly. Without repositionability, the tape would stick to the cylinder and have to be removed at additional labor and time costs, as well as extra cleanup of adhesive materials that would remain on the cylinder.”
Trust the process
According to JM Heaford’s Muncaster, plate mounting is now more important than ever. “With the trend toward shorter run lengths, many companies are now printing with a standard set of process colors (4,6 or 7-color expanded gamut) to minimize job changeover times,” he states. “This requires tighter register control, and therefore the accuracy of plate mounting is even more critical.”
With that in mind, it’s important to make note of the intricacies of the plate mounting process. Initially, the plate needs to be cut to the proper length for the plate roll onto which it will be mounted. “All mounting components should be handled at room temperature – or at least at the same temperature,” says Mark Andy’s Enright. “Ideally, a set of matched diameter plate rolls should be used.”
The back of the plate then needs to be cleaned with 100% isopropyl alcohol, using a clean, lint-free towel to remove any adhesive or contaminants. Enright adds that using a shop rag is not recommended, no matter how clean they appear to be, because they can introduce oily contaminants onto the back of the plate and the plate roll.
Operators must then clean their cylinders with 100% isopropyl alcohol, using a clean, lint-free towel to remove any adhesive or contaminants. When applying plate mounting tape, use a squeegee to assure a firm bond between tape and cylinder. The plate is then firmly secured to the tape by using a brayer roller to apply pressure to the entire surface, especially the edges and seams.
During the process, cameras need to be set to the correct position for the register marks/targets on the plate relative to the sleeve. “You need to line the printing plate so that the targets on the plates line up perfectly with the cross hairs – target – on the display monitor,” notes Muncaster. “Mounters use cameras, usually digital, to capture the image of the target on the plate and display it on the machine monitor.
The process does not need to be a long and arduous one, either. Depending on the type of mounting machine utilized, this process can take place rather quickly. “A fully automatic mounting machine (FAMM) can mount several plates on a sleeve in just a few minutes, while a totally manual mounting machine could take 15-20 minutes for the same number of plates on a sleeve,” says Tim Brannon, business development specialist at Anderson & Vreeland.
Avery Dennison’s Blackwell provides several tips to navigate the process. “To help prevent plate lift, leave at least 1" of tape past the edge of the plate,” he says. “Use plastic wrap on the plates if the prepared cylinders are stored for an extended period of time before or after use. Plus, when rolling the plate, apply extra pressure to the leading and trailing edge of the plate.”
According to Flint Group’s Kryeziu, Flint Group Flexographic recommends placing interleaf mounts in between plates when they are stacked on top of each other prior to mounting. “A clean back side of the plate, without any solvent residue from the platemaking process on the carrier film, is also critical,” notes Kryeziu. “Clean cuts on the plate edges when the plates are cut down to smaller pieces are also imperative.”
The skill of the operator is also an important factor to take into consideration. “Speed to mount will always depend to some degree on the skills, preparation and eagerness of the operator,” says Muncaster. “As technology advances, however, mounting is getting easier and quicker with less operator skill required. Our AutoMounters can complete the mounting process with total accuracy in less than a minute.”
It is important to note, too, that the evolution of flexo plates have improved the process. Flat-top dots provide converters with impression latitude, better print consistency and faster press start-ups. “With MGS’ LUX ITP technology, you get near 1:1 imaging with an optimized dot structure for better wear characteristics,” notes MacDermid’s Scogin. “What does that mean for you? With the bump curve greatly minimized, that means you have now opened your tonal range to print a wider range. This can give you cleaner vignettes, better highlight definition, or allow you to hit those ‘impossible’ spot colors with process color inks.”
Mounting made easy
The plate mounting process has improved dramatically throughout the years. The rise in automation has simplified the process while making it more time-efficient.
“Automated mounting systems are capable of mounting plates very quickly and with minimal operator interaction, resulting in a higher degree of accuracy,” says Mark Andy’s Enright. “Plate mounter manufacturers have designed plate mounting equipment that simplifies the mounting process while providing consistent repeatable mounting results, getting away from the old pull, stretch, tug techniques of plate mounting.”
The development of high magnification cameras and HD monitors on plate mounters allow the operator to quickly check the mounted plate horizontally and circumferentially for straightness prior to the plates going to press.
“Camera-based alignment systems have truly changed plate mounting,” states Anderson & Vreeland’s Brannon. “The days of a straight edge and marking the tape with a pen are long gone. Higher resolution plates really necessitated the change. Remounting plates due to registration issues has been substantially reduced.”
“Advanced image recognition systems automatically identify register marks of all different types to facilitate automatic mounting in combination with servo and stepper motors, providing extremely accurate and repeatable mounting, irrespective of the skill level of the operator,” says JM Heaford’s Muncaster.
As printing technologies have improved, brands are continually seeking shorter turnaround times for their labels. The products associated with plate mounting have had to keep pace. “The continual rise in the number of SKUs, along with more just-in-time ordering of packaging and labels, means a greater number of shorter runs,” adds Muncaster. “This increases the pressure on mounting departments as their workload will increase proportionally. With many jobs sharing the same set of cylinders or sleeves, the turnaround time between stripping plates and remounting also needs to be shorter.”
Plate mounting requires a host of supplies to make the process as seamless as possible. From mounting tapes to the systems themselves, converters rely on multiple products to produce high-quality labels.
From mounting training to tape selection, Anderson & Vreeland’s expert professionals can assist converters with a wide range of flexo needs. The company offers lint-free cloths, mounting machines, squeegees, facility-approved cutting blades, and quality mounting tapes, such as 3M’s E or L series products, to assist in this process.
For plate mounting tapes, Avery Dennison has developed its Fas-Flex flexographic plate mounting tape, which uses the right combination of properties with its closed cell foam structure to rebound and absorb vibrations. This translates to less gear marks, chatter and other print defects.
“The foam construction formulates dots that are small, tight, and reduces dot gain, allowing for smaller, crisper print jobs,” explains Avery Dennison’s Blackwell. “Clemson University conducted an independent study that found all of these properties were best-in-class against other industry competitors. We were fortunate to have a great product design out of the gate. We currently focus on improving product quality and delivering it to the customer more efficiently each and every day.”
JM Heaford offers a wide range of plate mounting machines, from completely manual machines through to fully automatic machines where multiple steps are all done automatically. This includes what the company considers to be the label market leader in the Heaford FTS mounter.
“We are continually developing the full range of our products, which are the largest in the market, from the most basic manual machine to the most automated one, as there is no ‘one size fits all’ for our diverse range of customers, from mom-and-pop operations to huge global organizations,” says JM Heaford’s Muncaster. “We’re learning from our customers every day and striving to develop solutions to help them address the challenges the market throws at them.”
Mark Andy offers several models of plate mounters, ranging from its flagship VPM-400 video plate mounter to very basic manual tabletop plate mounters.
Any and all of the required equipment for plate mounting itself can be obtained from the consumables division of Mark Andy, Mark Andy Print Products. Enright notes that Mark Andy Print Products is the largest global distributor for tesa tapes.
By Nathan Rank, technical support/project manager at AV Flexologic Americas, and Mike Agness, Hybrid Software executive vice president for the Americas.
The challenge with very precise plates, higher line screens, and expanded gamut printing requiring more plates on press, is that it has been tougher than ever to assure everything registers correctly—well, not any more.
Over the past few years, message-oriented middleware (MOM) and eXtensible Markup Language (XML) have been developed to coordinate software communication between prepress software and plate mounters. A MOM is software that sends and receives messages between two systems with a common goal—in this case, ensuring that plates are mounted perfectly onto a cylinder.
These software systems can coordinate locations of marks, distortion, number of cylinders (inks), etc. so that the mounting machine can easily guide its cameras to the position of the microdots and mount the flexo plate efficiently on the cylinder. The advantage is that with minimal time, we are proactively reducing errors and increasing accuracy. By digitally sending and receiving registration dot coordinates, we can assure they arrive to the mounter correctly and the operator has the right data.
If each of us measures the dots, it is likely everyone will get a slightly different number. We are trying to measure microns, but only when software talks to software are we going to be exact.
The benefit is quite simple. It takes only seconds of additional time in the prepress system to prepare but saves many minutes when the automated mounter cameras determine the correct position for the plates—and even more time if it is mounted imprecisely. Precision is assured to the micron and the only intervention by the mounting operator is loading the job’s filename—and placing the sleeve on the cylinder.
In particular, Hybrid Software has worked very closely with AV Flexologic and their label mounting machines to create an exceptional solution that works great for labels. The software utilizes MOM XML format knowledge for the mounter that they gained from their corrugated Patchplanner system. One thing they learned was that even corrugated printers, at times, used the mounter for full plates—not because they saved plate material for boxes but because they assured accurate mounting before the job was put on the press.
For narrow web plates, the AV Flexologic SAMM 2.0 800 (mm) has image recognition software that measures the exact position of the mounting marks before and after mounting. Ultra-high-resolution motorized Ethernet cameras move automatically into position. The robotic positioning of the plate is done automatically using the motorized front table and patented image recognition software. Laser pointers are mounted next to the cameras to indicate where the field of view of the cameras is. Thus, the mounting marks can be easily positioned in a fraction of time, instead of having to search for the them each time within the camera image.
After each plate is mounted, the SAMM mounting machine can automatically check the tolerance of mounted plates using image recognition. A PDF “quality report” is generated on-the-fly with the ability to check top and bottom.
“We are able to verify the precision of the mounted plate on the SAMM. The quality report provides a guarantee that the plate is mounted precisely,” says Rank. “Now, we can verify the precision of the plate on the press. So, the ‘wall’ between plate and press rooms disappears.”
“Very simply, we want to assure precision, from prepress to mounter,” adds Agness. “With this coordinated system, all plates are always in the same spot.”