Wednesday, August 11, 2010

Help! I think I need to link my color readings to my viscosity controller!

Help is not needed!

On a test in Turkey and Colombia we ran our viscosity control system against a favored falling dart system.

Our system showed the falling dart system's inability to reliably measure small changes in viscosity on a repeatable basis (see our water chart below). This means that their control logic cannot provide good control.

After all, if you cannot measure it, how can you control it?

Prior to our arrival the customer was convinced that they needed some kind of 'lockout' linked to their densitometer readings.

We said, "Please be patient, we have almost 80 years of experience in process control, we have seen this before, your problem is that your current control system is not holding viscosity."

Their response was: "Sure it is, just look at the display. The display hardly ever changes."

We said, "Just wait."

They said "OK"

So we installed our demo equipment on the same printing deck that the other viscometer was on and started up.

First we simply measured and showed the customer that while the other viscometer's display kept showing the same cup second, ours showed ongoing variations!

They said, "Woo, what is going on?"

We said, "They need to control their display with some kind of averaging or filtering, because they cannot measure small changes on a repeatable basis."

They said, "But we have used them for years"

We said, "That may be and that is simply years of wasted ink, substrate and time."

(Norcross can do well because we apply shear to the ink. Viscosity is a measure of shear force / rate of shear. Our falling piston really 'feels' the ink and thus we see changes that they cannot.)

So we put the other viscometer's system in manual mode and ours in auto.

Lo and behold the viscosity deviations stopped and so did the changing Delta E (color density).

They said, "Wow, you really do work"

We said, "Yes we do and what saddens us is that so many plants all over the world have tried other viscometers and have had bad experiences or don't even know what they are missing. Thus when we arrive we have to undo the fear and then prove our capabilities. But that is life and we are here to stay."

So the whole matter becomes simple, just use a good viscosity controller from a company that can teach you how to use them and knows about closed loop process viscosity control.

Then you are on your way ink savings of 25% - 40% plus less waste, happier customers and employees.


Best To All

Bob Norcross