CASE STUDY

Bent Journal

Customer had a concern about their new anilox having what appeared to them to be a bent journal or out-of-round defect. When the anilox was installed, the doctor blade would not consistently meter the anilox. There was a change in sound heard made by the doctor blade, a definite indication that something was not consistent. The ink film could be seen to change as the sound of the blade changed. The doctor blade was changed and the anilox was moved to a different print station, yet garnering the same results. The anilox was sent in to engineering in Charlotte, where no defect was found. The customer had yet another roll with the same issue, so it was at that time I traveled to the customer location to determine the cause of their problem.

Upon arrival, I examined the shipping container to make sure that the crate had not been damaged. This eliminated delivery as an issue. I looked at the long journal end of the roll for damage or sign that it had been dropped. No problem there. I took a look at the print station and did not see anything out of the ordinary, the bearing housing looked fine and all other rolls were not having this problem.

I asked the customer a few questions about the anilox. They told me that each new roll they purchase gets a new set of bearings. This is good practice, of course. I requested they try on the old bearings to eliminate the possibility of the bearings being the cause. Once installed, the anilox performed as expected, the blade sang one note only and the metered ink film was consistent. I asked them to contact their bearing supplier and see what the problem could be with these new bearings.

I have learned over the years the key to any mechanical troubleshooting is to never presume that anything is correct without testing it first.

Troubleshooting Ink Transfer

Customer was having problems with ink transfer to the plate and subsequently to the substrate. Initially, the customer had the plate cylinders removed and put on another press to trial, where they worked fine. The plate cylinders were of a rather large repeat with the correct mounting tape. I asked about the condition of the anilox; they were fairly new, they were clean and had been used successfully in the past. The only problem was achieving density and transfer. The customer had tried manipulating the ink system to no avail. This was also an ink system that had worked just fine in the past. So far, it appears the plate cylinders, anilox and ink system are performing fine.

I thought that perhaps there was something mechanical preventing the print cylinder from being tuned properly. I asked them what slot the print pin was in and had them move it up one slot as an experiment. The customer called back and the problem was solved. Having the print pin in the lower slot caused the print cylinder to get into a bind, making it difficult to adjust.

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