From the fluid dynamics perspective, how does changing the lateral movement of a roller in the inking system cause more or less ink to be applied in the circumferential direction of the plate cylinder?
This is exactly the question for which I have been looking for an answer. It made no sense to me that lateral movement could have an affect on how the plate got inked but since so many people were saying that it does, I am assuming that there must be a reason.
All too often, phenomena like this have some steps that printers can do to help reduce the problems but it is hard to find credible explanations of why those steps help. This is one of those situations.
So far, I have only some possibilities which can also be far fetched.
1. It may be that the ink film split ratio is different for when a roller is not moving laterally than when it is moving. This could result in changes to how the ink is stored on the rollers as the oscillating rollers go through their cycle. This change in ink storage might then affect the amount of ink applied to the plate. Just looking at the oscillating roller as it changes direction it is easy to see that the texture of the ink on the roller changes. So it might be possible that the split also changes.
2. Changing the direction of the oscillating rollers will cause an increase of load on the gear train of the roller train. Maybe this change in load affects ink transfer to the plate.
3. Maybe there is a mechanical linkage that when the timing of the oscillating rollers is changed, it also changes the timing of the ductor roller. It does make sense that if the ductor roller timing is changed, that that would cause a sudden charge of ink into the system which might hit the plate at specific locations.
Possibilities are not real causes and sometimes the possibilities can be very far fetched. Most of the time, the actual cause turns out to be something much more simple but was not seen at first.
Anyway, I would like to know too.
