Protecting Anilox Rolls and Filters

I remember a sales visit I made some years ago. While standing press side talking to the press operators and trying to write notes and keep my ear plugs from falling out, which would have made me violate company policy, but would not have damaged my ear drums as much as sitting through a Led Zeppelin concert in the 70’s!  I made a comment on the ink filtering systems that sat on each of the ink pumps.

It seemed that the printers were skeptical about the use of filters saying that they never really noticed any difference with or without the filters. I made some comments about size of mesh that they were using and whether they cleaned the filters on a regular basis. On further investigation it seemed that the filters were actually being used in line without the baskets inside them!  The baskets had long ago been crushed by some large piece of apparatus that had thrown its weight around in the wash up machine!

There is no doubt in my mind that a Filter with a magnet fitted is effective! They can save you thousands of dollars by preventing scoring on a printer’s anilox rolls, by removing debris that has found its way into the ink sumps, such as cigarette stubs, pens, ear plugs, hair nets, gum and out of date computers! In all seriousness they will prove the investment over and over again.  They do need to be looked after, press operators need to be aware that when the flow decreases then the filter basket is blocked and needs to be cleaned or replaced.

If you are tired of paying the invoices for repaired anilox rolls, tired of your customers telling you that the yellow you have painstakingly lay down for hours, is not their yellow and why does it have that streak across the red? Then it is time to consider some kind of filtration system. There are a number of ways you can filter the ink some simple and some elaborate.

The most common way of filtering ink is to use a canister type of filter that fits into your discharge ink line, usually after the outlet of the pump. They have stainless steel recleanable baskets, with varying size meshes, (see the enclosed helpful table of mesh verses micron sizes.) Make sure that the baskets are convoluted in their design, this increases the surface area for filtration, it makes the time between cleaning longer which helps the operator and makes them like the management more! If the funds are available try to buy additional spare baskets with your filters allowing quick changes between press runs.

Other filtering devices are Y type strainers which come in various sizes and can be fitted into the discharge line or directly out of the pump outlet. Small and compact, they have become popular with printers using diaphragm or peristaltic pumps because they are light and easy to plumb in. Baskets are cleaned by unscrewing the canister and removing the basket.  Please make sure that you do not change any baskets when the ink is flowing through the system or you will change the color of your press operators T shirts!

A secondary filtration device is a simple return line strainer. This fits onto the rim of your ink container and the return line is directed into the strainer, thus giving you another mesh size to take out further contaminates.  The whole idea of filtering your ink remains an invaluable one. The standards of packaging are of such a high quality and a printer should do all in his power to maintain that high standard which has made Flexography such a commanding force in the packaging industry.

Magnets:

Filters do not necessarily need a magnet. The inclusion of magnets has been a must with the use of enclosed doctor blade chambers.  For the metal shavings that are pulled off the rolls and blades are capable of damaging the press and cause streaking in the print quality.  Make sure you use a rare earth magnet and use one with a cleaning sleeve to allow the operator to remove the sleeve and the contaminates with it.

Mounting Your Filters:

Fitting a filter to a centrifugal ink pump is simple and easy. In-line Filters should have a tapped port on the bottom inlet which can be either screwed directly into the pipe work of your pump, and then a connection barb allows the discharge hose to be clamped on the top outlet.  Using a Filter on a peristaltic or diaphragm pump will require a mounting bracket attached to the press or a cart system. We recommend the use of quick disconnects to allow simple removal of the filter from the line for cleaning or basket changes.  The Y strainer can be fitted in to the discharge hose with corresponding pipe fittings. The extra effort put in by the maintenance team will, in the long run, prove to be very beneficial to your printing operation.

To conclude, I remember selling a Filter to a customer once, who was skeptical about whether he needed it. “Isn’t it just another bloody thing to clean?” he sneered. But when the results came in and he opened the filter to clean the basket, the amount of contamination proved to him that, yes it may be another piece of equipment to maintain, but it is worth the investment when your customer compliments you on the quality of your printing and the brightness of your colors! I believe that is what we are all aiming for, right?

Bill Mason
Sales Manager for Powerwise Ink Pumps
Erie, PA and Manchester, UK