CASE STUDY

Anilox Streaking

Dear Customer,

Harper visited customer to perform a pressroom audit to better understand the concerns in the press department. We evaluated the causes and possible solutions to the anilox streaks related to care and maintenance. We completed an on floor observation to witness pressroom concerns first hand. Below is a list of opportunities we feel will greatly decrease the level of streaks or dirty anilox at customer. From this memorandum, we will create a detailed strategic plan including procedures, training, and a follow-up trip for verification of each concern addressed.

Anilox Cleaning:

Press side cleaning is the most critical aspect of the cleaning process. Anilox rolls should be thoroughly cleaned as soon as the rolls come out of the press to maximize ease of cleaning. CeramClean II™ works very well for that purpose along with good old elbow grease and a good stainless steel brush designed for ceramic rolls. At Impaxx, you have the luxury of sinks at each press, making press side cleaning much easier. Allowing the ink to dry in the small cells creates a greater need for preventive maintenance cleaning. Another important point is the Lox Wash or just rinsing with water is not good enough because that will not remove ink that is already drying in the bottom of the cells. The procedure must be modified to reflect anilox cleaning (not rinsing) as soon as roll is removed. A sign off sheet can be added to the procedure that is monitored by management.

Preventive maintenance cleaning is just as it is stated and not to replace press side cleaning. There are numerous mechanical cleaners in the industry for anilox rollers that are operative. The waterbase ink system at Impaxx posses no threat, as long as good press side cleaning is implemented. With this cleaning practice customer will greatly decrease the need to overuse the ultra-sonic cleaning system.

Ultra-sonic cleaning is one of the most effective mechanical cleaners for waterbase ink systems. Ultra-sonic soak tanks are a two-part system; the solution and the high frequency sound waves introduced into the solution. For best results the anilox must soak for 2 to 4 hours in a heated solution, depending upon the line screen of the anilox roll will determine the length of ultra-sonic cleaning. General guidelines (heat solution to 120 degrees) 800 line 2 minutes, 700 line 3 minutes, continuing the progression as the line screen decreases. The reason for the augment in time is the wall structure of the anilox roll is greater as the line screen decreases allowing the ultra-sonic portion of the cleaner to be increased. Many cases this type of cleaner damages cell walls due to over exposure to the ultra-sonic portion of the mechanical cleaning system. The pH levels of the solutions used in tanks today are what Harper would consider high. The problem comes to concern from the length of time the anilox is exposed to the corrosive solution. Over extended time the solution will seep through the porosity (pin holes) of the ceramic and attach the base, thus resulting in blistering or delimitation of ceramic from the base. All ceramic anilox rolls have porosity and Harper anilox rolls are less than 1% while the industry average is 3%. With all that in mind, I am recommending to only use the ultra-sonic cleaning system as a last resort.

Recommendations / opportunities:

Anilox rollers are not being cleaned thoroughly when removed from the press.

Solution: Train each prepress person and operator on the difference between a clean anilox and a slightly dirty anilox is the first step. Many employees believe the anilox is clean when infact it is not. The end result is the anilox rollers are stored dirty allowing the ink to completely dry making it very difficult to clean at a later time. At this point the anilox may have streaks that appear on the anilox but not on the printed product. After a few cycles of ineffective anilox cleaning the streaks intensify and eventually show up in the printed product which mandates ultrasonically cleaned.

The second part of the solution is complete cleaning according to the attached procedure. During our press room audit John and I witnessed many anilox rollers new and old Harper and non Harper, with the streaks, hanging on the racks and in storage boxes. The practice at Impaxx is to quickly clean the anilox and place the anilox in storage. The next time the roll is needed the roll may or may not be cleaned but installed in the press anyway. The cleanliness factor is determined when installing the anilox in press by low density or poor print quality. At that point the operator will remove the anilox for proper and thorough cleaning causing excessive waste and downtime.

The use of air to dry anilox rollers after cleaning is another opportunity.

Solution: Clean the roll and dry completely with the white towels that are currently used in the pressroom. Many of the rolls have bad water stains, streaks and residual cleaning solution left on the anilox. After every cleaning step, Multi-Purpose Master Mix™, CeramClean II ™, or ultra-sonic cleaning the rolls must be rinsed with water and dried by hand with the white towel to complete the cleaning process.

Inspection of anilox after every cleaning.

Solution: After training of press personal at Impaxx everyone will be able to easily see if an anilox is clean. We do recommend a 200x scope to view the cells after cleaning each and every time. Let’s be honest if the anilox look really clean more than likely it is clean. If the anilox looks dirty than it is dirty. After training the entire pressroom will know what a clean anilox looks like versus a dirty anilox.

Other Opportunities:

Deck #4 on press #3 is not engaging the constant drive allowing the anilox to stop turning during down time.

Covers should be used on all anilox rollers to prevent the dings and damage in print areas of anilox rolls.

Investigate the possibility of slowing down the drying of your ink system to decrease drying of ink in the anilox cells. Average press speed 90 to 150 feet per minute.

Additional supplies recommended:

Multi-purpose Master Mix™, CeramClean II™, Sonic Wash Cleaning Solution™, 200x Microscope, and pH Meter.

I must stress that we at Harper are very concerned with this particular problem and support Impaxx and their efforts in trying to find a logical solutions to minimize downtime, waste and color striation due to the anilox roll. The above issues are infact impacting the quality of print. In order to correct the concerns we need your cooperation.

To summarize, Harper Corporation appreciates your business and will do whatever we can to incorporate the above opportunities. Thank you for the opportunity to put into practice all the tools we at Harper believe in. If you have any questions please feel free to contact me at 800-627-4784, Ext. 104. Otherwise, I look forward to meeting with you in the near future.

Best Regards,

David L. Brewer
Corporate Technical Manager
Harper Corporation of America

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