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Back to the Future

Written by:  Nick Liberto P.E., Powder Coating Consultants, Division of Ninan, Inc.

I thought now would be an opportune time to revisit a topic I and George Trigg first wrote about in this magazine in 1990 and again in 1995. Back then, we discussed color change economics and methods based on the available technology at the time. Back then, it was all about having duplicate equipment to shorten color change time. We even described systems that used multiple, sometimes color dedicated, booths and application equipment accomplished by push button when you turned one system on and the other off.

The “old way”

Funny thing was the very first powder spray applications systems didn’t use reclaim systems at all. They simply sprayed in a single collection system designed to separate the powder from the containment airstream and return the air back to the plant. Of course, all color and powder types were mixed together in this simple device that occasionally had to be cleaned and the collected powder tossed out. The simplicity of this system and short color change time was tough to match, but once someone decided to use the overspray powder as reclaim got complicated. Now cyclones were added to allow effective clean-up between colors by using the same collector (or baghouse in those days). Eventually, cyclones were replaced with dedicated cartridge modules and collection efficiency soared. As the systems got bigger and more complicated to collect every speck of powderoverspray,thecapita1cost skyrocketed and floor space requirements necessitated large buildings that looked like sports arenas.

Of course, these larger more complicated systems required significant time to execute a color change within the booth. Production impacts were mitigated by having duplicate, or more, booths to allow one booth to spray online while the other booth(s) were cleaned offline. The saying “more equipment is better” seemed to rule the day back then.

Back to the future

Well, the equipment suppliers in recent years have listened to their customers’ demands for quicker color change with less equipment by “back to the future” and de- highly efficient spray—to—waste systems that can perform color change in 12 seconds, or fewer. These systems use manual application equipment, designed with features that increase first pass transfer efficiency to a point that the amount of overspray is so insignificant that the time and cost to collect it for reuse makes no economic sense. Often, these guns are connected to “paint kitchens” where multiple hoppers or containers hold every color a company has to use, and the operator simply pushes a button to purge the gun and hose, and the color switches manifold connects to the next selected color. This means that one operator can spray any color on any part and change color in a 12-second gap on the line and paint the next part a different color. What could be simpler?

These fast-color systems have the added benefit of requiring smaller booths requiring less floor space and a lower initial capital investment. Many end users of powder coating buzzled their huge systems designed to meet “one piece flow” LEAN manufacturing techniques that reduced in process inventories and lowered overall operating costa. Now everybody is happy and people began saying

Other benefits of “small is good”

These learn systems had some side benefits. For instance, since color- change time was reduced and gaps to roll booths on/off line were eliminated, there was more production time available to coat parts. This resulted in slower line speeds, as more time was available to coat the same number of products. Slower line speeds meant that manual spray—to—waste systems could be accomplished by only a few sprayers, an important issue to eliminate automatic guns in older systems.

Slower line speeds meant that the rest of the powder coating process could be downsized as well, leading to lower operating costs, less energy consumption, smaller equipment footprints, less initial capital costs, etc. The savings from this reduced operational cost alone often justified the scrapping of the old system and the purchasing of the new equipment.

Summary

Just like fashion, in which women’s hem lines and guy’s lapels change every couple of years, the powder coating industry has again found that going back in time to resurrect a good idea (in this case spray-to-waste systems) can be very beneficial. However, I think I’ll leave my Nero jacket, platform shoes, and disco shirts in the attic for now at least. I didn’t look good in them when they were first in style anyway. PC

Copyright CSC Publishing

HieA Liberto is president o[Powder Coating Consultants (PCC), a division o[Ninan, Inc., 1529 Laurel Ave., Bridge report, CT 06604. Established in 1988 PCC is an independent specializing the use of powder cooling technology. Nick has more than 3 decades of experience in the powder coating industry and is a member o[many industry associations, including the Application Equipment Technical Committee of the Powder Coating Institute. A registered professional engineer in Connecticut, he holds a bachelor’s of science degree in mechanical engineering with a minor in physics. He can be contacted at 2031366-7244, email[pcc@powdercoat.com],- Web six from. powder cc.com].

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Editor’s note

For further reading, see the “Index to Articles and Authors 1990-2011,’ Reference and Buyer’s Resource Issue, Powder Coating, vol. 22 no. 6 (December 2011), or click on the Article Index at [www.pcoating
.com]. Article can be bought online. Have a question? Click on Problem Solving to submit one.