With the coil coating marketplace, including industrial coating industries, moving in the direction of more frequent deliveries of smaller and smaller lot sizes, often involving custom colors, the importance of color changes, setups and quality checks has never been greater.
Addressing these requirements in a time of increasing price pressure requires a re-examination of the whole coating application process to ensure that only the best practices and most reliable coating technology are being employed.
The Best of Examples
We have spent considerable time working with dozens of coaters over the past 10 years. During that time, we have come to the conclusion that, when properly controlled, the three-roll reverse nip-feed setup provides the best overall coating quality.
There are a couple of good reasons for this conclusion.
First, this setup provides tight edge-to-edge film control because the metering nip is constantly being flushed with fresh paint eliminating the edge-to-edge variations that build up in a traditional pan feed configuration. In addition, the metering nip pre-shears the coating prior to sending it to the applicator nip. This is important because most coatings are non-Newtonian, meaning that they are shear sensitive. These factors combine to produce a smooth, even surface finish.
The Worst of Examples
But there is always a trade-off.
In this case, the three-roll reverse nip-feed setup is the hardest to control for a number of reasons. First, there is an extra drive motor (for the metering roll) to contend with. Next, there are two nips (metering & applicator) to adjust and control, and often the adjustment of one affects the other, so it becomes a delicate balancing act.
And then it gets complex.
With two nips, there is greater heat generation from friction. This results in roll swell in the applicator and metering rolls, but often not at the same rate. This imbalance affects the adjustment of both nips and requires a skilled operator to both set up and maintain control. Furthermore, multiple quality checks are often necessary to confirm the setup.
This is why most coaters just stick to two-roll pan feed for their coating mode.
But there is a solution.
The Best of Both Worlds
The Profile Correction Module (PCM) makes a two-roll reverse coating setup operate like a three-roll reverse nip-feed setup in the coating system. With this new device, the paint is carefully metered to the pickup roll and because it is metered through a narrow gap, it is also pre-sheared before being sent to the applicator nip. This produces the same tight edge-to-edge film control and smooth surface finish as a three-roll nip-feed setup with none of the disadvantages.
With the elimination of the metering roll, there is no metering roll motor to power and control. This reduces energy consumption and maintenance since the roll doesn’t have to be replaced and reground regularly.
Furthermore, this configuration is easier to control, both during setup and throughout the run because there is no metering roll swell to contend with. This makes recipe replication easier meaning that it is easier to setup repetitive runs to the same settings (recipe) and to know that you are going to get the same results. This reduces setup time and quality checks, both on custom colors and on repetitive colors.
Saving Time and Energy
The PCM truly does allow a two-roll reverse coater to function like a three-roll reverse center nip-feed configuration. You get all of the advantages, and virtually none of the disadvantages. And with the time you save on setups and quality checks, you’ll be able to take advantage of the additional business opportunities that the quality improvements open up for you.
And that’s the best advantage of all!
Watch our free PCM Webinar to learn about how this innovtive technology can help your business.