Getting ink on paper: rebuilding the science of offset starts with density control

Print Action, Sep 2003 by Robinson, Jon

Advances in traditional offset presses have stalled as digital technologies and toners continue to be driven by research and development. PrintAction talked with Erik Nikkanen, president of Fountech and a mechanical engineer, about his radical ideas on redesigning the offset press. He believes the science behind controlling ink transfer can unlock a potential that the industry just refuses to see.

Where does the industry have it wrong when it comes to density control on the offset printing press?

People have been saying variation is inherent in the process or that it is a chemical process and this doesn't really describe what is happening. It also leads the industry into dealing with density control by measuring and then correcting. This is a common approach to the industry's solution to process control, that they measure and then correct. Traditionally, they've done it by having the operator look at it with densitometers, and now they use a closed-loop system, which is an expensive way to do it.

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Is closed-loop an effective way to do it?

It works but you are paying twice. You pay for a press that is supposed to give you consistent colour density and when it doesn't you have to pay again. The idea of process control in this industry is that you can't control something unless you measure it. Well, this isn't quite true.

You can calibrate something and if it's consistent you don't have to measure it any more. You make the process predetermined so that you have everything under control so that when [the press] starts up it goes directly to the density that you want, without any need for adjustment. Instead, the whole industry is based on measuring and adjusting.

Then what is the main issue of getting proper ink/water balance?

The heart of the matter is that the press is broken as a process and so the industry has compensated by having to take these steps to get things under control. But they are not looking at the source of the variation, which is the ink feed. People think density control has hundreds of variables when it actually only has this one variable. What I'm talking about is steady-state average density, which is what the printer wants. When they are running, they want the density to be the same sheet after sheet.

Why are these issues being ignored?

They aren't ignored, but it's in how you deal with the problem. If you don't know of a better way, you deal with it in the way you have - you measure it and when it changes you make an adjustment. A closed-loop system measures it and looks for the error between what it reads and what it should be, the target, and it makes a correction.

This is continuous inspection, which is not a popular manufacturing philosophy. A modern manufacturing philosophy is that you make a system that doesn't vary, not one that you constantly correct.

Can you give me an example of such a manufacturing philosophy?

I read this stuff back in the early 1980s about Toyota getting rid of waste. I'm not sure if it's from the book The Machine that Changed the World, but the concept called SMED, which refers to Single Minute Exchange of Die, was said to have made all the lean concepts possible. Toyota's idea was that you redesign a changeover so that it's as fast as possible. If you have a one-minute changeover, as your goal, that makes you think past continuous improvement. It makes you think in radical ways. To do that you have to actually understand the process, you can't do it by a shotgun approach. You do it by lean manufacturing.

Is Computer Integrated Manufacturing not an effective manufacturing philosophy?

It is only icing on the cake after you make everything work very well. CIM is a very marginal improvement. I read that the former director of CIMS [Center for Integrated Manufacturing Studies] at RIT, Dr. William J. Sheeran, in speeches he made at Digital Smart Factory and Seybold, didn't agree with CIM as being a big benefit. He argued that it's a minor benefit. You have to fix up all of these islands first and he was trying to tell them that, but they don't really listen.

He said a lot of modern manufacturing places are reducing their IT, taking it out because they are finding it is causing problems and he's actually saying they are taking automation out in some areas. His approach was more that you should use the right technology and you solve the problem with the appropriate approach and not just throw automation at everything. If you look at the Digital Smart Factory events over the years, they are moving away from the factory and they are moving toward IT for the customer and the frontend, because I think they don't know how to help the factory with IT.

What about presetting ink keys through CIM?

It's good in concept but the information to preset keys should be correct and the equipment should be capable of consistent ink delivery. Now the information to preset ink keys is not correctly calculated because the effects of wet trapping and other factors are not accounted for. The equipment is also not capable.