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Framing

Uwe Schulczek • Aug. 19, 2020

Framing

What do I understand by framing:

Framing is the negative ink build-up at non-printing points on the blanket cylinder (GZ) and impression cylinder (DZ). Caused by the 
Influencing factors:
  1.       Printing plates Poorly exposed, developed and gummed plates tend to scumming in non-printing areas
  2.      Dampening solution, alcohol and ink are not in harmony with each other. A contaminated roller mill causes poor ink/water emulsion
  3.      Mechanical factors Poorly adjusted inking and dampening units, rollers slipping sideways or slip to the printing plate and poor unwinding

The ink build-up in the non-printing area can lead to heavy contamination in the printing unit.
Often framing can be seen already at the delivery pile of paper.
In case of heavy contamination and paper pile differences, the delivery piles can also stick together.
Most of the times, framing also means a higher cleaning effort, as the washing systems of the printing machine do not get or reach all areas clean.
Framing is therefore: ink that is transferred to areas where these areas should actually remain ink-free.
The printing industry is becoming more and more focused on process optimization. All printing companies, suppliers, consumables or press manufacturers want higher, faster, further and, best of all, BILLY with a large margin. The causes for framing are very broad and there is no patent remedy. If you have framing under control on one machine, this does not mean that it will work on the other machine.
So individually one must look at it.
That's why "SUSTAINABILITY" is the keyword for framing.

Now let's get to the parameters that influence framing:

 Pressure plate
  •  Development
  •  Rubber coating
  •  Manufacturer
  •  Type
  •  Roughness

  Rollers / Roller adjustment / Mechanics
  • Cleanliness
  • Correct adjustment
  • Applicator rolls Lateral blocked out
  •  Roll type
  •  Shore hardness
  • Provision of printing
  • Bearer ring pressing

Dampening solution
  • Quantity
  • Glycerol content
  • Alcohol content
  • Contaminated
  •  Adapted to the product portfolio
Dampening solution supply
  • Lubrication limit
  • Vario

 Colour
  •  Rheology high tack/ low tack
  •  Adapted to the product portfolio

    Temperature in the printing unit
  •  Inking unit temperature control
  • Ductor temperature control

 Rubber blanket
  •  Good Quick Release behaviour
  • Elevator height
  • Underlay sheets

These are a lot of sources of error and mean meticulous work to combat framing. It's possible.
It is important that you look at all the parameters and analyze them. First the plate and its manufacturer/type/development/rubberization. Each manufacturer and type is different. Because of the plate structure, material and composition.
TIP!! Use a correction pen to edit a non-printing area outside of sheet sizes and while printing judge at this point.

The reaction of the plate to the fountain solution is as important as the tack and the fountain solution absorption of the ink. The interaction is a development process that takes a long time and requires many tests with different consumables.
Tip! Due to the surface tension, a little more alcohol has a positive effect.

It has become clear that the ink and dampening rollers are one of the biggest influencing factors. Their condition, surface, especially the adjustment are of importance.
Here are a few "not so" pictures from practice.

Ink form rollers that are poorly spaced laterally have a negative effect. It has proven to be a good idea to adjust the dampening form roller to the plate and dampening distributor thinner to counteract the slipping behaviour.
Excerpt from Wikipedia: Slip (from "slipping") generally refers to the deviation of speeds with each other in stationary mechanical elements or fluids under tangential load.

I.e. due to the frictional contact of the plate cylinder (PZ) to the dampening form roller (FAW) and their different speeds, an uncontrollable mechanical state is created. The fact that the channel drop also causes speed differences makes it impossible to counteract this slip. Unless the different speeds can be controlled.
Now some question will arise: But for this you use Vario! Yes, Vario is beneficial and also gladly used, now Vario serves to slow down the humidifier which in turn drives the FAW. The speed reduction is very popular, because it erases slugs from the plate and clean surfaces and gradients can be printed with it. However, this speed cannot be adjusted but is given by the design. Only the platen speed can be controlled! To reduce or even prevent slippage, the FAW should be adjustable in speed.
At the moment there is nothing we can do against the slip, we can only laminate the effect.

If you want to or have to print long runs, then place a format sheet under the blanket that is 3mm smaller than the printed sheet. This prevents the build-up GZ / DZ. Gladly done with UV- print with interdeck dryers, otherwise you can only scrape off the ink with a spatula, because you cannot adjust your Interdeck to the format.

Conclusion: Framing is a complex topic with many facets and sources of error, therefore it requires a conscientious and sustainable approach to get it under control.

I am looking forward to suggestions, additions and comments. 

Your Uwe Schulczek

   

Dampening System

von Uwe Schulczek • 09 Juni, 2020
Right at the beginning I would like to link the pictures here on top! You are welcome to leave your opinion about them in the comment field. I think that with these dampening systems no proper printing is possible anymore, but in offset printing the dampening system is an important factor for stable and good results or print products. Due to my worldwide activities at printing machines it can be seen that not always production printing and therefore missing maintenance intervals or cleaning work lead to problems in the dampening system. Again and again it comes through: incorrectly adjusted rollers, heavily worn rollers, Wrong roll cover / rubber, incoming chrome distributors, wrong additions, bad IPA or IPA replacement, to dirty fountain solution, the wrong cleaning products, leakage in pneumatic cylinders, to problems up to unwanted machine downtimes. The problems often show up in toning, smearing, emulsification of the ink, lack of color brilliance, color fluctuations, framing, etc. I don't want to go into detail now, but it must be mentioned that fountain solution plays a major role in a well-functioning dampening system. Especially the parameters additives, roller material and print product should be coordinated with each other, i.e. with which raw water quality, which roller material and which print product (labels, packaging etc.) you start with. These are only some of the basics to be considered. You can read more basics in my book "Printing Inside". Often badly adjusted rollers are a reason for the problems. So the adjustment to the plate can be checked quickly, also the pan-roller and chrome-distributor-roller usually make a good impression. Since it is directly in the viewing area. But many operators shy away from removing the chrome- distributor-roller (Dicke Berta) and checking the adjustments of the other rollers, or out of ignorance. The time required for this is rather short if used regularly. Tap forwards / backwards a few times and an assessment of the parallelism and thickness of the contact strips is done. Even small adjustments are possible. When times come, the dampening unit should then be completely removed and the roller surface and diameter checked. Of course the rollers can also be replaced. In this breath, cleaning of permanently installed rollers is a good idea. If you are unsure about how to adjust the dampening units, you can refer to the operating instructions or get help from instructors. Aids such as a strip card or even a NIPCON for assessing the contact strip thickness would be advantageous. A moisture test form such as the one from Fogra will help to find the optimum setting. It is also important which washing agent you use to clean the dampening unit or dampening rollers. Not all washing agents are suitable or approved for the roller material in the damping unit. Defective surfaces in the material and/or impurities in the dampening water can quickly occur. If you are not sure whether and which washing agent is suitable for your dampening rollers, you can ask the manufacturer or supplier. Conclusion: By checking the adjustments and visual assessment of the roller surfaces, problems can be prevented. It is also advisable to control the process water and to coordinate it with the printing and press portfolio. A more stable and qualitative production can be achieved by regularly applying the controls. Comments and feedback are welcome. I now wish everyone a good time and much success. Your Uwe Schulczek
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