Maximum gap between ink key and ink fountain roller

[Deleted member 16349]

I am looking for some general background information.

The ink keys are set over the range from fully shut and almost touching the ink fountain roller to fully open at 100% coverage. Let's say the fully open position is the maximum ink key gap.

On your presses, what are some of the maximum ink key gap opening dimensions?

As an example maybe it might be 0.020" or about 0.50 mm.

Thanks for any responses or comments.

Erik

 

[GazKL440]

to be honest Erik i dont think i have ever run a 100% key, or measured the gap! from memory, and this is hazy, i would think somewhere up around .5mm but in general when you have no ink in ducts they will be zero set for washup then opened to be cleaned, so i cant be too sure...

 

[Paultheprinter]

I will check after washup tomorrow, i assume you only want to know split duct type keys not the older single blade ducts, my guess is more like 1-1.5 mm. On the speedmaster the keys are like little excentric cams, i will measure lowest point to highest at fully open position, my only concern is that after duct protecting foil and liner are in position the key opening distance might not be that good of an indication of the thickness of the film of ink or volume of ink transfered through the duct only a relative value if that make sense.


Paul

 

[Deleted member 16349]

I will check after washup tomorrow, i assume you only want to know split duct type keys not the older single blade ducts, my guess is more like 1-1.5 mm. On the speedmaster the keys are like little excentric cams, i will measure lowest point to highest at fully open position, my only concern is that after duct protecting foil and liner are in position the key opening distance might not be that good of an indication of the thickness of the film of ink or volume of ink transfered through the duct only a relative value if that make sense.


Paul

I know from tests that the ink film is not equal to the gap. There are ink flow conditions at the gap that will affect that actual ink film thickness on the ink fountain roller. Differences in the angle of the ink fountain blade or key surface relative to the ink fountain roller surface can have quite large impact on the ink film thickness relative to the gap.

The question was aimed at what the gap values are in general, on common ink fountains since most ink fountains have relatively similar geometry. I agree with what you said that the ink film is relative to the gap. The specific ink film thickness is not so important to know as long as it is consistent. That makes sense.

I am guessing that printers are much more likely to know the zero set gap than the 100% gap.

If you do have a value it would be interesting to know.

Thanks.

 

[Paultheprinter]

hi erik,

its nice to know that you understood the point i was trying to make but i was very suprised today when i maxed the keys out, i was expecting to keys to roll back to leave a large clearance but in reality it was maximium 1.5mm more like 1mm in reality, i will take feeler guages in monday to get exact measurement but it shocked me the lack of movement needed, all printers on speedmasters know that even on the heavyist jobs the keys dont realy go past 15 big spots (cpc lingo) but with the keys on 24 the clearance was so small, just suprised as the gears on the ink key motors are not exactly that fine

Paul

 

[Alois Senefelder]

re - Ink Key Gap

re - Ink Key Gap

Hello Mr. Erik Nikkanen,

The maximum gap openings on present press designs are in the range of ----

300 ---- 500 microns

300 microns = 0.3 mm or 0.012 inch

500 microns = 0.5 mm or 0.020 inch

I enclose some PDFs


Regards, Alois

 

[Alois Senefelder]

re - Ink Gaps # 2

re - Ink Gaps # 2

Erik - some more PDFs


The Hantscho Ink Fountain is from 1977


Regards, Alois

 

[Deleted member 16349]

Erik - some more PDFs


The Hantscho Ink Fountain is from 1977


Regards, Alois

Alois, thanks for providing the PDF's. The diagrams and the values were interesting.

 

[Deleted member 16349]

hi erik,

its nice to know that you understood the point i was trying to make but i was very suprised today when i maxed the keys out, i was expecting to keys to roll back to leave a large clearance but in reality it was maximium 1.5mm more like 1mm in reality, i will take feeler guages in monday to get exact measurement but it shocked me the lack of movement needed, all printers on speedmasters know that even on the heavyist jobs the keys dont realy go past 15 big spots (cpc lingo) but with the keys on 24 the clearance was so small, just suprised as the gears on the ink key motors are not exactly that fine

Paul

And just imagine when you have low coverage and there is some disturbance in the roller train, like changes in water or temperature, how that is going to affect the ink transfer from the ink fountain roller to the roller train. Quite big changes in the percentage of ink feed can happen which are not readily visible at the ink fountain. A 10% change in a 0.005" ink film is 0.0005". That's a small amount.

There are ways to make this much more reliable and consistent. I am always amazed that it works at all as well as it does now.

I will comment more on this but I have to travel now. There is a real opportunity in this area and it is not just the ITB.

Have a good weekend.

 

[Deleted member 16349]

There are ways to make this much more reliable and consistent.

I will comment more on this but I have to travel now. There is a real opportunity in this area and it is not just the ITB.

Have a good weekend.

Paul,

To continue the discussion on the potential of the ink fountain related consistency and predictability issues.

There are two basic issues related to the accuracy and consistency of the ink feed into the roller train. One is the accuracy and consistency of the metering on ink onto the ink fountain roller and the second is the accuracy and consistency of the transfer of ink from the ink fountain roller to the roller train. The ITB is designed to provide a consistent ink transfer condition instead of the inconsistent ink transfer condition of the traditional ductor.

So let's look at the consistency and accuracy of the ink metering methods. There are probably hundreds of versions of the traditional proportionally variable ink key to ink fountain gap concepts that have been developed since they first were used, over 150 years ago. Alois has shown some in his PDFs but just about all the concepts used in printing are of this proportionally variable gap between the ink key and ink fountain roller.

So over the 150 years, the printing engineers have mainly refined the same idea over and over again but not really innovated away from that concept. There are exceptions in the newspaper press technology but for commercial printers, you have had the same technology for a long time.

The problem with the proportional ink metering concept is that as you get down to very low coverage, the error starts to increase proportionally. This was referred to in the last post. Part of this problem is due to the difficulty in obtaining and accurate zero set point, which is the datum for any presetting and also the minor variation in ink metering at such a small gap.

To automate a proportional ink key gap is expensive since you usually require a feedback method to confirm the actual position besides the expensive drive for the ink key, which could be a servo or stepping motor plus its controls.

There are less expensive and more accurate ways to meter ink onto an ink fountain roller. Over ten years ago, I had an idea of a binary ink fountain. One where the ink key is only in one of two positions. Open or closed. Unfortunately this idea had been already covered by a patent (US Patent # 4328748 ) by Manroland.

With this concept, the ink is metered not by proportional ink films thicknesses applied to the ink fountain roller but by a single constant ink film applied to the ink fountain roller in proportional amounts of timing. Open 5% of the time and closed 95% of the time would represent a 5% ink feed. Open 45% of the time and closed 55% of the time would represent a 45% ink feed.

The beauty of this concept is that any error in the ink metering, through the constant gap opening, is the same for high coverage or low coverage. It is also linear from 0% to 100%. A very nice mathematical relationship.

Also the drive for the binary ink key is can be very simple. An inexpensive solenoid and a relatively low cost PLC to drive on/off control to the solenoid.

Now for the good news. Fortunately the Manroland patent has expired. Their great concept can not be used with a conventional ductor because of the problem with the timing of the ductor and the on/off ink feed of the binary ink key feed. Their concept is very compatible with my ITB (US patent #6,857,366 Canadian patent #2,288,354), since the ITB will transfer basically whatever the ink metering system provides. The ITB does not care if the ink film is proportional or binary as long as the total volume of ink metered matches the requirements of the printed design in line with the ink key.

Manroland wasted a great patent because they did not think the problem through. Fortunately the potential is still alive and anyone can use it with the ITB or similar concept.

I hope that you can see that there is potential for more accurate and more consistent ink feeds that will cost a lot less than what exists now.

 

[Paultheprinter]

Hi Erik,


your spot on with the low ink coverage issues and i think heidelberg addressed the symptoms with the short inking thain systems on there pressses but obviousley not addressed the problem, i feel now that Heidelberg have taken the Anicolour route this will render the ink train as we know it redundent (in time) probably to leave us with other related issues with its design. My concern is that your ITB seems to be a great soloution but does it have and place in the market and is it good enough to get printers to change there ethos of "im so skillfull i gould get anyhting to print consistantly", ive only been in the trade for fifteen years but i do feel such a major change in press design would russle some feathers. Also is this system able to be fitted to most presses and at what cost?

Paul

 

[Deleted member 16349]

Hi Erik,


your spot on with the low ink coverage issues and i think heidelberg addressed the symptoms with the short inking thain systems on there pressses but obviousley not addressed the problem, i feel now that Heidelberg have taken the Anicolour route this will render the ink train as we know it redundent (in time) probably to leave us with other related issues with its design. My concern is that your ITB seems to be a great soloution but does it have and place in the market and is it good enough to get printers to change there ethos of "im so skillfull i gould get anyhting to print consistantly", ive only been in the trade for fifteen years but i do feel such a major change in press design would russle some feathers. Also is this system able to be fitted to most presses and at what cost?

Paul

Paul,

I am not a manufacturer. My market is to sell or license the technology to press manufacturers.

Printers should not worry about their skill levels being reduced too much. There are a lot of other potential problems on a press to still keep them busy. Also having more consistency and predictability should keep them in business longer and extend their craft life.

The ITB is very simple and very inexpensive, since it basically requires an extra pickup roller and the blade assembly. This is low tech. There is relatively no training required since the operator just does what they normally do except that with the ITB they would not have to worry about the density drifting off.

Because the ITB is so simple, it can be applied to just about any sheetfed press. It can be applied to many web presses if there is enough room. Some web presses have some limitations on room in the lower units of presses which have horizontal web paths. Therefore the ITB is a technology that has the potential of extending the life of many legacy presses by making them consistent and predictable.

The ITB is not just a technology. It fundamentally changes the way the process works and if implemented the industry would be forced to rethink their view of how the process works. A lot of experts will be put on the spot for their lack of understanding. The experts have held back the progress of the industry for a very long time. It is not because they have done this on purpose but because they have also been victims of their own misconceptions. Science aims to find out the truth. Technology has no such aim. The experts in this industry tend to be technology oriented and not science oriented. There is a very big difference.

The ITB would show that the real world performance of density control with respect to consistency and predictability can be mathematically defined and the level of performance can be designed into the press. It would open up a whole new science for developing offset presses at lower cost. The Anicolor, is interesting but it is not the future of offset printing. It is an idea from the past.

The ITB is not the only or even the best way to obtain consistency but it is a very inexpensive way and one that can help the industry to bridge the gap to the future.

I have to add that I don't make any money on the ITB unless I license or sell it to a press manufacturer. In the end, they would only buy it if it worked. Talking about this potential does not pay any bills and at this time, I am the only one pushing for a rethinking of the process. How can that be?

The potential is there but it needs action from the parties in the industry that have the resources and have the motivation to make a difference.

 

[carto-man]

New to the site

New to the site

Erik,

I totally agree that offset needs to thought as a science not an art. All too often people in the business call printing an "art" when they don't understand how a press system works, the lack of understanding color was a good example of that! Many printers still don't understand color, they still talk densities, which is almost a useless measurement for color except for maintaning ink film thickness. I'm in the wide web folding carton business and I can tell you first hand that if offset doesn't get better (easier), flexo will take over that business. I was reading a thread the other day about toning, you had said that you saw a chronic toning problem with a ManRoland Cartoman, I'm a process manager of a 44" cartoman and fight with the problem often. I would love to hear any feed back you may have on this subject. I think we have one of three Cartoman's left in the world.
Thanks,

 

[carto-man]

New to the site

New to the site

Erik,

I totally agree that offset needs to thought as a science not an art. All too often people in the business call printing an "art" when they don't understand how a press system works, the lack of understanding color was a good example of that! Many printers still don't understand color, they still talk densities, which is almost a useless measurement for color except for maintaning ink film thickness. I'm in the wide web folding carton business and I can tell you first hand that if offset doesn't get better (easier), flexo will take over that business. I was reading a thread the other day about toning, you had said that you saw a chronic toning problem with a ManRoland Cartoman, I'm a process manager of a 44" cartoman and fight with the problem often. I would love to hear any feed back you may have on this subject. I think we have one of three Cartoman's left in the world.
Thanks,

 

[Deleted member 16349]

Erik,

I was reading a thread the other day about toning, you had said that you saw a chronic toning problem with a ManRoland Cartoman, I'm a process manager of a 44" cartoman and fight with the problem often. I would love to hear any feed back you may have on this subject. I think we have one of three Cartoman's left in the world.
Thanks,

Cartoman,

Yes, toning especially at the trailing edge of the plate. Operators forced to run with too much water. In our case, we were printing with EB inks, which probably made the problem worse but my view is that it was design related. We even expected this problem before the press was installed.

The Cartoman press, which was a North American designed Manroland press had IMHO a dated roller train design which encouraged starvation ghosting. The dampening problem was chronic and the concept of huge cassettes was strange to us even at that time. Now one can get a similar capability with a sleeve that one person can easily install in a press with the VSOP concept that Muller Martini just bought from the recently bankrupt Drent Goebel press manufacturer.

I will be happy to discuss the particular issue of toning on that press with some history but let's do this offline. Contact me at [email protected] and I would like to know what company you represent just in case they are direct competitors with the company I was with at the time.

It is an interesting story and in retrospect it supported the view I came to have that press manufacturers can be good engineers of the mechanical systems but lousy scientists of the process.

 

[junker1984]

On Heidelberg presses equipped with CPC, the prescribed gap when the LEDs are "1" in the coarse and "4" in the fine should be .004". Be mindful you are slipping the feeler only at the ink gap.