by Robert Allsop*
While powder coating as an industrial finishing technique remains strong in North America, the possibility of incredible growth opportunities opens up rapidly every day throughout the Far East, and Central and South America, as well as in Africa and the rest of the world.
In North America, it currently accounts for 12% of the total decorative coatings market. According to the Powder Coating Institute, about 5,000 industrial finishers in North America applied more than 370 million pounds of powder in 2006 on an innumerable variety of products thanks to the high quality, durability of the finishes along with the highest efficiency and maximum compliance with environmental regulations.
Although it is not disputed that powder coating offers several advantages, some questions should be asked when deciding what type of powder coating operation is right for you. In today's lean manufacturing environment, downtime can be costly. That's why one of the most important questions that needs to be answered is whether dust is recovered or sprayed with waste.
Spraying without recovering may seem like a contradiction to one of the main advantages of powder coating—namely, the ability to easily recover and reuse overshoot paint—but depending on your situation, this may be more cost-effective at the end of the day. Several modeling tools have been developed to help evaluate different options and variables when making this decision. Below are some examples taken from a few different scenarios that demonstrate the cost differences between traditional color changes, rapid color changes, and waste spraying with color on demand.
Technology changes the dust
Along with technological advances in powder coating there are new and innovative ways to apply such powder, and to improve efficiency in its application. For some time, powder coating options have varied from manual small batch systems to fully automated, multi-cab systems and rapid color change with self-propelled input and output.
Today's technology eliminates the need for additional dust booths and color modules for every color that is sprayed. This saves space, energy and capital investment, and gives the possibility to spray any color without buying new equipment. Current technology also allows color changes to be made in just 5 or 10 minutes with dust recovery systems and in 20 seconds in systems without recovery.
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Color changes in less than 20 seconds weren't even an option a few years ago, but new technology allows you to change color on the fly with almost instantaneous agility. There are also new spray guns that use powder transfer in "dense phase", allowing to achieve a transfer efficiency of more than 70% in a first pass. Not only does this provide excellent dust coating on difficult parts, but it also significantly reduces the amount of dust used—and wasted.
Like liquid paint cookers, several dust transfer hoppers that feed a single collector make almost instantaneous color changes a reality. This capacity significantly reduces the cost gap between recovery and non-recovery. At the same time, powder manufacturing capabilities have evolved so that there may be an even wider selection of low-priced powder coatings that influence the decision.
Recycle or not recycle
Determining whether or not to recycle dust is actually a numbers game—an estimate of labor and material costs, as well as the cost of downtime. In a lean manufacturing operation, the cost of downtime can outweigh the cost of labor and material. Team budget aside, here are some common factors that could (and should) weigh on the decision:
1.How many color changes (per hour, per shift, per day) should be made?
2.How quickly can color changes be made?
3.How much labor is available for color change?
4.What is the cost of labor?
5.How close to capacity is the line?
6.How much production (profits on products) is lost during downtime?
7.How expensive is my powder?
8.How much capacity do I have to process the parts in batches?
9.Hourly cost of the overloaded line?
Next, you need to join the answer with these questions to find some of the possible solutions. Although there are many models and options to choose from, dust systems tend to fall into a few broad categories of dust equipment.
1.Color change systems in large volumes
These have been the reliable tools in plants with large production volumes that use a few colors in long runs and where it is possible to process parts in batches in longer production runs of a single color.
Such facilities are excellent for recovering a high percentage of powder coatings that yields a total system efficiency of 98.5%. Often, these larger cabins require 30 to 45 minutes for a normal color change. This group also includes entry and exit designs in multiple self-propelled input and output cabins.
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2.Faster color change systems
Over the past five years, several rapid color change systems have gained popularity. Color change times have been reduced to the range of 10 to 15 minutes using cyclone technology, automated dosing centers and new composite materials in the easier-to-clean booths. Self-cleaning cabins have been designed whose walls and floors blow automatically to expel overshot dust.
These cyclone systems are in high demand where several color changes are required per shift. The recovery of a high percentage of powder coatings produces a total system efficiency of 95%.
3.Adjusted systems (Color on demand)
The most recent developments in powder are systems where the recovery of powder coatings is not possible or economically justifiable. If the cost of labor is high, the cost of dust is low, and there are frequent changes, then spraying without recovering may be the most sensible decision.
Developments such as dense phase dust transfer have given sufficient impetus in transfer efficiency in a first pass that the cost gap of dust recovery and or disposal has narrowed considerably. An additional weapon in the color change arsenal is the recent ability to automatically change colors in twenty seconds or less in a tight cell. This super-fast color change capability allows guns and hoses to be quickly purged for a second color.
Computer modeling tools can be used to test key parameters, such as lost production time. While plant supervisors and operators may focus on factors such as transfer efficiency, management may view the greater impact of color change as a loss in production time. This is especially true for plants where the value of the products sold is very high and the plant operates with a high utilization of its capacity.
Maximize uptime
The value of lost production can quickly tip the balance in favor of any alternative that maximizes the paint line's productive "uptime"—outpacing factors such as labor costs and dust savings.
The question might no longer be whether the powder coating with rapid color change is right for you, but which option is the most suitable. Today, there are all the tools to make good decisions. There are more tools and technological options to compare each option against any series of requirements. With so many powder coating options, the possibilities with this material are tremendous as technology continues to evolve.
*Marketing Manager Powder Systems and Industrial Coating Systems of Nordson Corporation. [email protected]
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