Archive for the ‘Printing’ Category

Does Flexo Printing Affect Gamma Ray Sterilization

February 10, 2014

Steve asks:

Well, I’ve got an interesting one for you.
We have a major customer who is a global leader in medical device manufacturing. We have a 55” long x 4 x 1 catheter package we do for them. 100% flexo printed. Their question is… “Do we have any documentation, or data on whether flexo print on corrugated affects the characteristics and performance of Gamma Ray sterilization?” We are quite comfortable with data we have on ETO (ethylene oxide) but Gamma is sketchy territory.

Would you or perhaps Clemson have any input for us? The engineers are looking to provide a rationale in their proposal for FDA etc.

I can honestly say that is a question I’ve never been asked before! For insight to this question I reached out to our friends at BCM Inks for some input. Ted Vernardakis, Ph.D., R&D Director/QA Manager for BCM Inks offers this explanation.

“Gamma rays are the most energetic, most powerful and most penetrating radiation of the electromagnetic spectrum. They are more powerful and penetrating than X-rays. They travel through just about everything except lead. Therefore they pass through corrugated board and flexo printing unobstructed, like a hot knife cutting through butter. Corrugated board and/or flexo ink has no effect on Gamma Ray sterilization, whatsoever.”

Hope this helps.

—Ralph

Disposing of Ink Buckets and Cutting Dies

March 7, 2013

Chase asks:

Our plant uses a lot of ink and are constantly obsoleting cutting dies. Both of these process leave us with a waste stream that I cannot find a buyer for. The ink is in standard 5 gallon buckets and we have switched to all plastic handles to make it easier to recycle and take a step of removing metal handles form the process so the whole bucket can be recycled, but i cannot find anyone who wants to fool with the recycling of these buckets even thought the ink residue is water soluble and non-toxic.

We wash these out, but are not in the business of cleaning ink buckets we are a corrugated converter, so there is still some ink that is not washed off. On the other hand is our cutting die situation. Do you know of a good way to recycle or otherwise use these dies without just tossing them out? It is costing us quite a bit of money for extra dumpsters to handle the buckets and dies.

In the January/February 2013 issue of Paperboard Packaging Magazine’s Products & Services section (page 22) there was mention of a Die Recycling Program developed by Triangle Dies & Supplies. They may also have an option for your ink buckets.

You may want to contact them. http://www.tridies.com
-Ralph

Print Striping/Banding Issues

January 17, 2013

Victor asks:

We have been experiencing print variations when we print full coverage. The best way to describe this is that it looks like bands of light then dark print that run horizontally, across the entire width of the press. Similar to when an anilox is hitting the plate too hard, but is not. Sometimes it’s not as obvious at the beginning of the run, but becomes more noticeable after 200 to 300 sheets. Other times it’s obvious from the start. Have you heard of this happening and/or do you have any suggestions?

I reached out to Jack Fulton at Printron and through his sources he offers this info.

There are a number of variables that can create banding or striping when printing.

If the plate is larger than the sheet you will not transfer all of the ink from the plate to the sheet. So the remaining ink will cause uneven printing on subsequent sheets.

Banding or bumping can be caused by several things in combination with each other. If pH or viscosity is out of control it can make the problem worse. If using plastic doctor blades and 60 degree cell anilox rolls you can get a phenomenon like stripping a screw. If you put a screw into a piece of wood and turn it too tight you can strip it. It feels tight then all at once slips. The same thing happens here, the blade is tight against the roll, then slips and re-seats which causes the uneven inking or banding. Ink with more lubrication works best in this situation.

Some converters have reported experiencing banding on diecutters when the doctor blade angle was set at 60 degrees. When changing to a new doctor blade system with the blade angle at 32 degrees the problem went away. If you measure the opening between the two blades in chamber and it’s the same as the distance between the bands you are printing, then this may be the issue.

Also if your chamber moves laterally, or oscillates, stopping the chamber from moving laterally may help this issue.

You may also want to make sure the anilox roll pressure, not the impression but the pressure engaging the roll, is correct. If this is too low it can cause bouncing even with very light impression. You may want to contact your OEM for the correct specs and test procedures.

Printing over corrugator scores

November 21, 2012

Jeff asks:

What’s your experience with printing over Male to Flat scores?
We have a carton that has a solid yellow that prints over the bottom depth score. The solid plate is only 3 x 34, but it completely covers and runs parallel with the bottom depth score. Plates are .250 Cyrel.

I reached out to Rick Pomerenka at Printron for some help on this question. Rick shared this knowledge.

A thinner plate package(softer durometer) will not help drive the plate into the bottom of the score. Whenever our customers want to print over corrugator scores they order the sheets with flat female scores. This does not eliminate the crush issue, but it helps greatly and they are more successful printing over the score. In these situations we have found a .250 polymer plate mounted on .030 PVC works best.

Sponge backed plates are too soft and will not allow you to transfer the ink into the valleys of the combined board.

–Ralph