Category Archives: Cleaning

Anilox Roll Cleaning Essential to Effective Ink Delivery

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by Flexo Concepts

Anilox_Cleaner_300X298You spend plenty of time selecting the correct anilox roll for a job. Careful consideration goes into line screen, cell geometry and cell volume in order to guarantee that a precise amount of ink or coating is delivered to the substrate. Aniox roll cleaning is essential to maintain this precision. If you neglect to clean your rolls on a regular basis, you will not get the most out of your anilox investment. Plugged cells will affect print quality and cause you frustration, waste and downtime. An anilox cleaning program consisting of daily, weekly and deep cleaning will preserve the integrity of the anilox engraving and ensure quality, press efficiency and longer anilox life.

When a newly engraved anilox roll arrives from the manufacturer, volume is even across and around the surface of the roll. As the roll is used, however, a residual amount of ink or coating material is left behind in the cells after the transfer has taken place. The residue dries and creates build-up in the cells.  Over time, these deposits decrease the capacity of the cells and reduce their ability to carry and release the volume of ink or coating for which they were designed. This residue also raises the surface tension, or dyne level, of the roll and increases the tendency of the coating to “cling” to the surface. When this occurs, the roll will not release the proper volume or ink or coating to the plate.

Benefits of regular anilox roll cleaning:

  • The repeated transfer of a precise volume of ink or coating
  • Consistent coverage
  • Reduced labor and less downtime
  • Fewer job rejections and waste
  • Longer anilox life and lower re-working costs

Flexo Concepts recommends a 3-step anilox roll cleaning program:

1. Daily wiping to prevent ink or coating build-up
Applying a liquid cleaning agent by hand and wiping down the roll with a clean, lint-free cloth on a daily basis is the simplest and most effective way to prevent keep ink and coating from drying and building up in the cells. As a basic rule of thumb, the best time to clean a roll is as soon as it is removed from the press. The longer inks, resins, adhesives, etc. have been allowed to sit in the engraving, the harder these materials are to remove. To maximize cleaning performance, choose a cleaner specifically formulated to remove water-based, UV or solvent-based chemistries based on your application.

2. Weekly scrubbing with a paste-like cleaner and an anilox cleaning brush
brush_ss_orange_450X268
Manually scrubbing the roll once or twice a week with a brush and a paste or cream chemical cleaner will mechanically loosen and remove any ink or coating residue that remain in cells despite daily cleaning. The cleaner is applied to the roll, vigorously scrubbed in a circular motion with an anilox cleaning brush and flushed with water while the roll remains in the press. It is important to remember that stainless steel brushes are suitable only for ceramic anilox surfaces and brass bristles should be used for chrome surfaces to prevent damage to the engraving.

3. Monthly deep cleaning to remove tough ink or coating deposits
Over time a residual amount of ink or coating material is left behind in the cells and the roll requires a deep cleaning to remove these tough deposits. The most common methods of deep cleaning are chemical wash and ultrasonic. The roll is removed from the press and placed into a chemical bath where it soaks in a powerful cleaning solution before being subjected to a high pressure rinse or ultrasonic vibrations to loosen and dissolve the deposits. These methods vary in cleaning effectiveness, risk of damage to the roll, and water and chemical consumption.

Like on other parts of the press, a maintenance program for anilox rolls keeps the ink delivery system running at its peak. Regular anilox roll cleaning will prevent anilox cells from plugging with ink and coating residue and stop build-up before it dries. Maintaining anilox rolls through a regular cleaning program can pay off tremendously in terms of maximizing print quality, press efficiency and cost control.

Click here for more information on our anilox cleaning brushes

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Minimizing Plate Costs: Part 2 – Plate Demounting

FlexoGuide-600

By Tim Reece, All Printing Resources

Introduction

This multi-part article will explore some of the more common but less controlled causes for replacing the photopolymer printing plate. Reasons for replacing an expensive photopolymer plates can vary greatly. In Part 1 of this series we focused on many advantages of deep plate cleaning with automatic plate washing systems, including how we extend the life of the plate. Part 2 will focus on minimizing damage during plate de-mounting, while the final chapter will address how to properly identify a worn plate and taking the “guessing” out of the decision to replace the plate.

Where Plate Damage Occurs

In this article we will turn our primary focus to plate demounting. Those who imagine plate and tape removal to be a relatively simple task, have most likely not performed this task and been held accountable for plate damage for an extended period of time. It seems that we take great care during the methodical steps of platemaking to insure a quality plate has been manufactured, free of pinholes and with optimal relief and exposure. After leaving platemaking these plates are handled with care and trimmed to size with care before being mounted and wrapped in opaque polyethylene to protect them from harmful UV, ozone and surface debris and scratches. Then it’s time for the plate to do what it was created to do; transfer a beautiful multi-colored artwork to the substrate. The marriage of plates starts

Image A

Image A

peacefully with a kiss impression. But after that optimal setup check and the thumbs up from the supervisor to “run it”, the plate that was handled so carefully prints what can be millions of feet of product and running sometimes in excess of 2,000 fpm, not to mention exposure to solvent mixtures that swell and abrasive white inks that wear on the plate surface. This sounds like a harsh environment, and it is, but this is NOT where most plates are damaged or worn out. More plates are deemed unusable after incurring damage during demounting, or the stripping of the plate from the stickyback. When polling convertors, an estimated (average) of 78% of plates are replaced due to damage versus the plates actually wearing out.

Oh, The Shame…

Image B

Image B

If it wasn’t bad enough that an expensive plate is damaged beyond use during the demounting process, it often gets worse. We have made it a point to inform employees how expensive a photopolymer plate can be. So when an employee inadvertently tears a plate during demounting, believe me they get a sick feeling in their stomach. People who would never consider damaging company property and take pride in their job, with one slip, just a little too much pressure, or pulling at the wrong angle tear the plate. The dilemma now is to report it, or quickly hide it in the trash and hope it will be classified as “lost” or maybe the job will incur a change in artwork and it will all work out. Of course the problem comes when the damage does go unreported and the platemaker is already behind and thinks he/she is going to just pull the “full” set from storage.

Avoiding the Tear

Image C

Image C

Plates damaged during demounting typically fall into two different areas, tearing the plate at a stagger (see image A) or creasing the Mylar backing by pulling the plate in an offset angle from the plate cylinder or sleeve. When carefully trimming a plate, often just prior to the mounting process, we often need to trim 90 degree cuts where the design nests or lanes are staggered. It is at the inner angles that the plate is most susceptible to tearing during demounting. No matter how careful the trimming, the two cuts intersect one another creating a small slit that allows tearing to easily occur when removing the plate from the mounting tape (see image B). The individual can do something so easy at this point to minimize this mousetrap. Simply take a commercial grade hole punch, and punch out the area of the intersecting cuts (see image C). When the plate is pulled from the tape the force will follow around the radius of the holes before changing in the Y to X axis. You will be amazed at how well this method works. Industrial handheld

Image D

Image D

hole punches cost around $50 and can punch a variety of holes sizes, not just the standard 3/4″ although that size does work well. The larger the diameter of the hole, the more that forces is spread and the better the result, but in some cases the convertor may choose something smaller, not to cut into the artwork. A Kongsberg (see image D) table takes an automated approach to plate trimming with the ability to trim multiple plates from a master sheet of polymer with radius at each critical area prone to incurring damage.

Everybody’s Got an Angle

The second area that damage occurs during demounting is creasing the Mylar backing by pulling the plate in a non parallel angle from the cylinder in hopes to get it to release from the mounting tape (stickyback). It’s difficult to tell the person demounting the plate to “just pull the plate away and parallel from the cylinder. The fact is that if it was that easy, that is exactly what they would be doing. When demounting a plate by hand, many of us refer to a method coined by 3M as the “low and slow” technique. Folding the plate over on itself or pulling the plate side to side inevitably will result in some damage to the plate. Removing the plate in a steady slow motion while using a low angle of peel (less than

Image E

Image E

90¡) will help minimize damage to the plate (see image E). Still we must consider that after a plate is mounted, the adhesive level typically increases. The reason for this is because when we mount the plate, we want to be able to easily reposition the plate. Once the plate is mounted we want it to stick aggressively until the order is run, then magically release. The truth is that it increases in adhesion, and impression in press only enhances this effect. The result is a plate that often doesn’t want to release, and a lot of pulling back and forth and side to side to get it to release. There have been cases that the employee pulling the plate or stickyback from the print cylinder actually pulls the cylinder off the cart or stand in which it is resting. Considering the awkward movement and amount of force required to get the plate to release by the employee, it isn’t hard to image damage to the plate, or worse yet, physical injury to the employee. It only makes sense that this would be a likely area for automation.

Automated Demounting

Image F

Image F – Click the image above to learn more.

Automated plate demounters are designed to automate the removal of polymer plates and tape (stickyback) from sleeves or print cylinders (see image F). The effectiveness of these demounters is only enhanced by the plate punching methods and use of automatic cutters like the Kongsberg table. The auto demounter replaces the need of an operator to remove plates or mounting tape by hand, an operation that can be particularly time consuming especially for wide web plates. The demounters can be equipped with an expandable shaft, allowing the machine to work with all sleeve inner diameters or work with conventional plate cylinders. The cost savings in time and damage to plates can be great; the operation of these machines seems rather simplistic initially.

Once the mounted plate cylinder or sleeve is placed in the demounter, a key part of the demounting operation takes place. A specially coated pneumatic roller gently moves forward to prevent damage to the plate and locks on to the lead edge of the plate. Once this “clamp roller” locks down on an edge of the plate, the machine gently pulls the plate off of the sleeve or cylinder perfectly parallel and at a constant (controlled) speed and peel angle without tearing the photopolymer. The very same process can be used to then remove the mounting tape.

Current automated plate demounters do require the operator’s assistance in releasing the initial lip of the plate to start the removal process. The reason this intervention is required is to address butt fit plates, radical plate gap patterns and step and repeat staggers. The is most safely executed by using a plastic tool with a flat beveled edge to start to lift the plate without fracturing the mylar backing which can occur by using ones fingers.

More to Come…

In Part 3, we will look into minimizing plate costs by using a quantitative process determine how we can be sure a plate is worn and no longer suitable for use. 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.

apr-logo-new-200APR 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 have felt your pain. For any specific questions please feel free to contact me at 847-922-0134 or treece@teamflexo.com.

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Minimizing Plate Costs: Part 1 – Automatic Plate Cleaners

 

FlexoGuide-600

By Tim Reece, All Printing Resources

Introduction

There is certainly no shortage of articles written on how to store and handle photopolymer printing plates in order to maximize performance and extend life. We know that exposure to ultraviolet light and ozone damages the plate once it reaches production, but when it comes down to reasons for replacing an expensive photopolymer plate the reasons vary greatly. In this multi-part article we will explore some of the more common, but less controlled causes for replacing the plate.

  • Plate cleaning
  • Plate de-mounting
  • Identifying when the plate is worn

First Things First

In this article we will turn our primary focus to plate cleaning. Most of us understand the basics of plate cleaning. We know the importance of selecting a compatible cleaning solution, acceptable methods of wiping the plate to avoid damage to screens, and the importance of cleaning the ink from the plate sooner than later after the production run is complete. There is one aspect of plate cleaning that remains somewhat inconsistent that has a tremendous effect on plate life and performance, and that is a consistent deep cleaning into the screen areas of the plate.

Taking a Closer Look

Image A

Image A

It is reasonable to assume that a .067″ plate that contains screens would have a plate relief (distance from face to floor) of .018″ – .025″. However if we take a cross cut section through a screen, we can easily see that the relief area between the dots within the screen is actually much less than the surrounding relief. Space between individual dots routinely measure .006″ – .010″ (see image A).

Image B

Image B

The same holds true for fine reverses within solid print areas (see image B). It is in these areas that ink remains after what can be a good attempt at cleaning the printing plate. The problem isn’t just that the effort isn’t put forth to clean into these areas, it’s the fact that the ink has often thoroughly dried and a saturated lint free cloth or coarse bristled brush just doesn’t have the ability to clean deep

into these areas.

The Dirty Truth

Image C

Image C

The result of insufficient cleaning into these problematic areas can drastically diminish plate life and performance. As seen in image C, the relief within a screen can be reduced greatly as ink builds up. This often results in dirty print within the production run.

Image D

Image D

Even after a valid attempt of cleaning, ink often remains in these areas (see image D) and is sent into storage to await the next order. When that plate is pulled from storage and mounted back in the round, that dried ink has one of two directions to go. It either remains locked to the floor

within the screen, further reducing the relief and leaving the potential for fill-in; or it begins to flake out in small pieces and is released to the substrate or is re-deposited. Either way, the quality of the print is compromised. When asking a press crew the question, “Do you have a problem with the consistency of plate cleaning?”, the answer may often be “no” or “I am not sure.” But rarely is the answer “no” when asking press crews if there is ever a problem with dirty print or streaks in the anilox cells from ink particulate lodged between the doctor blade and anilox roll.

Wash Your Hands of the Whole Mess

Image E

Image E

Automatic plate cleaners were designed not only to effectively clean plates in these problem areas, but they also offer a much more consistent “hands free” result. Not unlike the plate processors that washout out the relief between images and dots during the manufacturing of the plate, soft bristles scrub deep into the relief areas of the plate using solutions that are compatible with solvent, UV, and water-based inks. Some solutions are suitable for all three ink types. The result is a plate that has been returned to its original condition in regards to cleanliness and relief (see image E).

Sooner is Better When it Comes to Cleaning Plates

It is generally understood that after a press run, plates should be cleaned as soon as possible to avoid ink from thoroughly drying on the plate. Ink that has been left to dry for an hour or even more not only requires the individual to work harder to clean the plate, but it also begins to affect the surface energy of the plate which may lead to long term inconsistencies in ink release from plate to substrate. When testing the effects of dried solvent inks on plates, the surface energy had a difference of up to 6 dyne when compared to plates that were cleaned immediately following the production order. This also indicates the importance of consistency when cleaning the plate surface.

Automation Justification

So if it is understood that it is important to clean expensive photopolymer plates immediately, why doesn’t it always happen in this fashion? A simple fact is that some people just don’t like to do it… me included. Cleaning a plate with large solids is relatively easy, but even given the correct solution, lint free cloths, and soft bristle brushes, it isn’t easy to get all the ink out of a screen area. Some individuals claim that the repetitive scrubbing motion gives them pain in their hands and wrist. This repetitive motion can cause muscles and tendons in the hands and wrists to tighten up and lead to carpal tunnel syndrome, and other forms of repetitive stress injury (RSI). But beyond just not wanting to clean plates, the people cleaning plates are often the same people focusing on getting the press set up for the next production order. So even though we say we want the plates cleaned immediately, we may not be willing to enforce this if it has a negative impact on press uptime, so plates often get put by the wayside. Because the operator is not required to babysit the plate washer, it is much easier to get plates cleaner and faster following a press run by allowing pressroom personnel to drop the plates onto a conveyor or multi tray stacking system, letting the machine wash, rinse, and dry the plates.

How an Automatic Plate Washer Works

The dirty photopolymer plate is automatically carried into processor by the transfer rollers. The plate transport speed and temperature are controlled by the computer for consistency; both of which are features that are hard to monitor and maintain when performing this task by hand. Soft bristle brushes with alternating and floating movement offer maximum cleaning capability, while ensuring no damage occurs to the plate. Taking this process out of the hands of various individuals also ensures the correct “safe” cleaning solution is be used, and items like nylons or other abrasives do not come into contact with the plates. Because of the “floating” brush design, any thickness flexo plate will be cleaned quickly and effectively in the automated system. Two types of rinsing systems are available – an open rinse system with fresh water that is led to a drain and a closed loop recirculation system.

More to Come…

In Parts 2 and 3, we will look into minimizing plate damage through automated de-mounting and determine how we can be sure a plate is worn and no longer suitable for use.

apr-logo-new-200APR 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 have felt your pain. For any specific questions please feel free to contact me at 847-922-0134 or treece@teamflexo.com.

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What do I do with my “old” cleaning solution?

From What’s the BuZZ? by Sonic Solutions

About 2 or 3 times a month, I get a call asking what should be done with old – used – spent cleaning solution.

I wish there was an easy answer, but there really isn’t. With the EPA and various other agencies that are in place to protect us and the environment, there is never an easy answer.

First step is to get a copy of the products MSDS. We ship one with each container of Sonic Kleen that we sell. If for some reason you misplaced it, email me and I can send you one. Then call your local waste authority. Ask them what you are permitted to do and act accordingly.

We have found a few things that seem somewhat consistent with your requirements.

First, you can neutralize the cleaning solution so that it’s pH becomes closer to a pH neutral. This will make disposing of the old solution easier. We sell a Citric Neutralizer (Part SK-100 – $220) that will help in your efforts.

Second, it seems common that the authorities will require you to dispose of the solution in a similar manner to the way that you dispose of your waste inks. In some communities you may need to have the items removed using an approved waste hauling company.

In either case, make sure you check with and follow the direction of your local waste authority.

“90/10 – Max 5″   90% Soaking – 10% Ultrasonics – No more than 5 minutes of ultrasonics each time.

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Life Cycle of a Cleaning System?

From What’s the BuZZ? by Sonic Solutions

So how long will an ultrasonic cleaning system last? Well you might find yourself comparing equipment in the shop to our equipment. Will it last as long as a press, or rewinder, or a fork lift?

 Probably not. But if you really understand that the ultrasonic equipment is more like your cell phone than a press, you might be more realistic. Now that doesn’t mean that the ultrasonic equipment will only last a year. What you need to understand is that this is a pretty technical piece of electronic equipment. You can’t just beat on it 24 – 7 and expect it to last forever.

What are the top 3 things you can do to keep the system going for years?

  1. Keep it clean and wipe up spills.
  2. Keep it clean and wipe up spills.
  3. Keep it clean and wipe up spills.

See a pattern yet? Cleaning solution and electronics just don’t mix. 

Also, never place and use the system on a rolling cart. Make sure it is placed on a solid sturdy table near a water source. Sprinkle in a little TLC for your turner too every few months.

Use and care are the biggest factors in the longevity of cleaning systems. The longest lasting I’ve seen is just over 13 years. The average is between 6 and 8 years. As I said before, care is the biggest factor in making them last longer. Spend a little time with yours today to help it last longer. How old is your system?

“90/10 – Max 5″   90% Soaking – 10% Ultrasonics – No more than 5 minutes of ultrasonics each time.

 

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How long will cleaning solution last?

 

By Sonic Solutions, What’s The BuZZ ?

The life of the cleaning solution will be dependent upon a number of factors including: What types of inks are you using (water based? UV? Solvent?), How dirty are your rolls?, Are you diluting the solution?

What types of inks are you using?
Sonic Kleen is a water based cleaning solution. For water based inks, the contents of the cells will absorb into the cleaning solution. Because of this the cleaning solution will become contaminated with the dirt and debris from the anilox. Over time these contaminants will reduce the effectiveness of the cleaning chemicals and the chemicals will become less effective in softening up the contents of the cells. As this saturation level goes up, the cleaning times will also. UV and Solvent inks will float on top of the solution. Very little of the contents of the inks will then absorb into the cleaning solution so the solution will last longer.

How dirty are your rolls?
Cleaning solution will be impacted by how dirty the rolls are. Just like in the above explanation. As the solution gets saturated with dirt and debris, the solution will become less effective and soaking times will increase. First time cleanings (since the rolls are loaded with dirt) will use up solution quicker. On the other end of the spectrum, if you clean rolls after every press run, the rolls won’t be very dirty and the solution will be impacted the least. Also, if you do this, you know that the rolls will be 100% ready for the next print run.

Are you diluting the solution?
If you dilute the solution then you are basically reducing the chemical concentration of the cleaning solution. As you clean the rolls the dirt and debris taken out of the rolls will work against the concentration of chemicals. If there is more dirt than the chemicals, then the cleaning effectiveness of the solution will go down. Using the solution undiluted will help the solution to last the longest.

Don’t forget the purpose of the cleaning solution. Its job is to soften up the dirt and debris from the cells of the anilox. If it can’t do its job correctly, then the cleaning process will take longer. Time is money, so see what is your balancing point. Always remember the “90/10 – Max 5 rule”.

“90/10 – Max 5″   90% Soaking – 10% Ultrasonics – No more than 5 minutes of ultrasonics each time.

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Line Counts

“What’s the Buzz?” – Sonic Solutions

Occasionally we will get asked questions about an anilox roll’s line count and how long we recommend using the ultrasonics to clean the rolls.

It’s pretty clear that as the line count goes up that the thickness of the cell walls goes down. They surely get dirty and plugged up pretty quickly too.

I understand what the roll manufacturers say about minimal ultrasonics, but I think they are a bit too conservative. What I think is most important is as the line counts go up is a stricter adherence to the “90/10 – Max 5″ rule. It will be even more important to thoroughly soak the roll to make sure the cell contents are as soft as possible. Then a quick application of ultrasonics should do the trick.

Don’t forget to keep the ultrasonics at 5 minutes or less. Make sure that the cleaning solution is in good condition too so that the soaking time is being best utilized.

I also recommend that you don’t go too long in waiting to clean a high count anilox roll. In fact, right after the print job, take the roll out of the press and clean it right away. The contents of the roll will still be pretty soft and the ultrasonics won’t have to work too hard to clean the cells out. Plus, the next time you grab the roll, you’ll know it’s ready to go. Just remember the “90/10 – Max 5″ rule.

“90/10 – Max 5″   90% Soaking – 10% Ultrasonics – No more than 5 minutes of ultrasonics each time.

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When Dirty Rolls Get Clean

From What’s the BuZZ? by Sonic Solutions

We are often asked the question, “How often should I clean my anilox rolls?” That’s a great question. Over the years, we’ve asked our customers how often they clean their rolls and have found that they vary from one end of the spectrum to the other. We have some customers that will clean their rolls after every press run and we others that clean their rolls once a year – whether they need it or not! Where are you on this spectrum?And, where should you be on this spectrum?

Here are a few things to take into consideration in deciding where you should be. Is you company Proactive or Reactive? Can you risk loosing a job because of poor quality? Do you want to minimize the setup time for your print jobs? Do you want to run your print jobs more efficiently – saving time and money? If you wait too long to clean your rolls and it impacts your printing, then you’ve put yourself into a losing situation already.

It’s our opinion that you should clean your rolls after each print job. The ink and resins will still be soft in the cells, so cleanings will be quick. Minimal ultrasonics will be safer for your rolls. Every time you start a job, you will know that one variable (ink volume) will not be the problem for your printing so setup time will be less. Because your rolls won’t be as dirty when you go to clean them (as opposed to being fully plugged), you won’t use as much cleaning solution, and your cost per cleaning will go down.

We’ve found that those customers who clean more often tend to be the larger companies, have multiple shifts, have plenty of work and are more profitable. Where are you in this spectrum?Where do you want to be?

Don’t forget.   “90/10 – Max 5”   90% Soaking – 10% Ultrasonics – No more than 5 minutes of ultrasonics each time.

Visit Sonic Solutions for more cleaning solutions

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