How to Best Manage Color Changes in Industrial Finishing

    Posted by Mike Bonner

    Jul 10, 2015 11:00:00 AM

    industrial finishing coating system

    Regardless of the application method, color changes in industrial coating and other coating systems require a cleaning process to clear the current color and load the next. In the case of coil coating, color changes are among the most expensive of any of the processes. They involve wasted paint, consumption of cleaning solvents, downtime, labor, scrap materials – the list seems nearly endless and completely daunting.

    Many of these costs are documented in our prior blog titled, “6 Ways That Changing Colors Can Disrupt Coating Technology." But the situation is not hopeless.

    Too Much Paint

    If we boil it all down to the fundamental root cause of color change problems, it is that there is just too much paint in the delivery system. By definition, the delivery system in a typical two-roll reverse coating system includes the pump (or pumps), the hoses (including the suction tube, supply and return hoses, troughs, etc.), the pan and the rollers (pickup and applicator). To be certain, the largest of these volumes is the paint in the pan.

    The sum of these, often referred to as the “fill volume," is the minimum amount of paint required to keep the coater running. It is the volume that you have to pump into the system before you can start coating, and it is the volume left over at the end of the run that has to be pumped back to the drum (even if the drum is empty). It is this volume that creates excess waste and partial drums – the bane of every coil coater.

    Reducing Fill Volume

    For years, coaters have tried everything imaginable to reduce the volume of paint in their pans. Size reduction and advanced contours have had some positive effect on reducing fill volume. But at SCS we decided that to truly eliminate the pan fill volume, the best approach was to eliminate the pan!

    Now I know what you’re thinking: “There’s no way to eliminate the pan from this system!”
    But as it turns out, we’re both right – you just have to think “outside the pan”!

    The PCM

    We took our observations, collected from more than 10 years working with dozens of different coil coaters and came up with an entirely new approach to two-roll coating. We call it the Profile Correction Module – PCM for short. This new system allows you to reduce the volume of paint in your system, while at the same time improving:

    • Finish quality
    • Edge-to-edge consistency
    • Repeatability

    How does PCM do this?

    In essence, this innovative new device makes your two-roll reverse pan-feed coater behave like a three-roll reverse nip-feed system, with all of the advantages and few of the drawbacks.

    A Different Approach

    It is well known that three-roll reverse nip-feed coating systems provide the best overall finish quality and edge-to-edge film build control. In fact, we have seen many coaters try to emulate this by using “baffle boards” pressed against the pickup roll. This falls short because there is still a significant volume of paint in the pan.

    The PCM, on the other hand, is completely separated from the pan. It reduces system fill volume by creating a controlled metering gap along width of the pickup roll. Because paint is no longer picked up from the pan, the volume of paint in the pan is removed from the coating equation. In essence, the pan becomes a “catch basin” whose sole function is to route paint back to the drum.

    Huge Savings

    This simple change of philosophy reduces the paint in the pan from a “fill” to a “film," and in doing so, removes gallons – in some cases tens of gallons – of paint from the system fill volume! And with top coat paints running in the $70-$300/gallon range, this represents hundreds, or even thousands of dollars in job cost savings.

    Download the free Dimension Request Memo to learn how we can customize solutions for your line.
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    Topics: paint and coating, Industrial finishing, PCM

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