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Training painters and supervisors pays off handsomely
Training Painters and Supervisors Handsomely
Pays off
by Ron Joseph Ron Joseph & Associates
Inc., San Jose, Calif:
A
nyone who walks into the average painting facility knows how much dirt and overspray surrounds the paint shop. Engineering managers who know every detail of their NC machines, robots, and high-tech welding operations often take the long route around their paint shops because of this low-tech, dirty, and sticky eye-sore in the middle of an otherwise immaculate fabrication shop. Money is often available for training the sheet metal folks, but somehow the budgets are “coincidentally” depleted when the subject of painter training comes up. This paper provides an insight into the advantages that can be reaped by training the paint supervisors and painters. Such training can be unsophisticated and relatively inexpensive, but there is always a lucrative financial payback. Rather than cover a comprehensive training agenda, this paper will provide only a glimpse of the issues that were covered when I recently visited an aerospace painting operation. EFFECT OF THE SPRAYBOOTH
ON PAINTING
DEFECTS
One of the most troublesome areas in a painting facility is the spraybooth. An abundance of paint defects and failures is generated here simply because of poor spraybooth design and maintenance, and an understanding of how a spraybooth works. Typical problems that occur in thousands of facilities each day include dust in freshly painted finishes, overspray, orange peel, blushing, cratering, dry spray, and more. In large painting operations the cost to prevent or minimize these defects probably exceeds tens of thousands of dollars per year. Yet, in most cases, it is fairly simple to address the problems and very little, if any, capital outlays are required. Over the past 15 years I have discovered to my surprise that most engineers, supervisors, and painters don’t have a clear understanding of how their spraybooths function and why a uniform airflow is so important. It doesn’t take a rocket scientist to appreciate that turbulent airflow in a booth can cause dust and overspray to settle on freshly painted surfaces. A 38
few months ago I visited an aircraft facility in which an aircraft is positioned with its tail toward the filters and its nose pointing to the double swing doors at the entrance of the booth. Painters were terribly frustrated. When they painted the tail (closest to the exhaust filters), overspray was carried to the front of the booth and settled on the nose. This wouldn’t have been .too serious except that the tail was painted with gloss white polyurethane and the nose with a gray. Now perhaps you can better appreciate their frustration. The cause of the problem was poor airflow through the booth. Not understanding how a spraybooth functions, the painters were not careful to properly shut the double doors, and the large gap between the leaves caused unnecessary turbulence. The booth had an air make-up system and the incoming airflow rate didn’t match the exhaust flow rate. In fact, the exhaust was pulling so much air that the personnel access doors on the side of the booth were difficult to open. This implied that the booth was operating under severe negative pressure. On occasion someone would enter or leave the booth while painting was under way, and that caused no end of additional turbulence. On one occasion I watched as small bits of masking paper and masking tape lifted clear off the floor and flew directly into the freshly painted fuselage. As a result of this experience I asked the paint manager if he would allow me the time to take the painters into their break room for a short impromptu training session. Fortunately, the supervisor joined us and within 45 minutes I had explained how their spraybooth functioned and why they were experiencing so many problems. Thereafter, they immediately implemented a rule that the double doors were to be properly shut at all times, and the broken seals between the doors were to be replaced. The window in the access door was thoroughly cleaned of a thick layer of overspray so that people on the outside could now see when painting was taking place. Nobody was allowed to open the door until the painters on the inside gave the okay. The imbalance of airflow between the supply and exhaust plenums was largely due to poor engineerMetal Finishing
Figure 1. Manometer
without
fluid.
ing and the fact that the booth was old and needed a thorough overhaul; however, there were other factors that only worsened the situation. Baffles on the supply plenum had been rotated on a random basis in the hope that this would lessen the turbulence. Some baffles were missing. The exhaust filters at the other end of the spraybooth were plugged with overspray, and a filter change was long overdue. Once again, I took the paint supervisor and his painters aside and explained why it was so important for no one, other than an air ventilation technician, to touch the supply baffles. As to the exhaust filters, I showed them that there was no red dye in the manometer attached to the outside sheet metal of the booth (see Fig. 1). Without the dye they could not possibly know when to change the filters. In the presence of his colleagues I arranged for the lead painter to replace the fluid. He then zeroed the manometer, and we discussed how to determine when it was time for a filter change. There was no argument when I showed them that the first-stage roll filters had been so poorly suspended from the ceiling that overspray-laden air could bypass the first stage and quickly foul the second-stage pocket filters, at $36 each (see Fig. 2). In less than 5 minutes they learned the proper technique for changing the filters with the result of improving capture efficiency and extending the life of the second-stage filters. To my great pleasure everyone showed real interest. ORANGE PEEL DEFECTS
The typical “orange peel” paint defect really bothered them because no matter how diligent the painters were at setting up their HVLP spray guns they March 2002
Figure 2. Poorly positioned
filters.
could not eliminate the problem. One glance at the compressed air hose and fittings explained it all. They had three quick disconnects (QD) in their 1004% long air hose; one at the regulator on the spraybooth wall, one at the handle of the spray gun, and the third connecting two 50-R hoses to make a single long hose. To add insult to injury, the air hose was y4 in. in diameter. Again, the problem was easily solved after I took another few minutes of their time for training. They were shown how pressure drops occur in a long hose, whether air or fluid. Using some pressure gauges we experimented with the existing y4- and a new %-in. hose. The QDs on the regulator and between the two 50-R hoses and all remaining G-in. fittings were replaced with %-in. connectors. To their delight they watched as the pressure differential between the regulator and the handle of the spray gun decreased. Finally, they could get adequate compressed air to the spray gun and wave goodbye to orange peel. But not so fast. Because the facility is subject to the Aerospace NESHAP, they are obligated to demonstrate that the atomizing air pressure never exceeds 10 psig. Fortunately, I had a suitable replacement cap and pressure gauge for the Binks Mach 1 HVLP gun, 95P cap, and was able to demonstrate how to keep the gun in compliance with the NESHAP. Some of the more enthusiastic painters wanted to check their own respective guns for compliance, and one painter who was using a DeVilbiss HVLP gun asked his supervisor to please purchase an appropriate cap/gauge for him. The training was a success. Not only did the 39
painters all but eliminate the orange peel defect, they were now aware of compliance issues and could prevent an unwanted Notice of Violation. WATER SPOTS
did the painters occasionally have water spots in their finishes? They were all aware that the moisture trap needed to be drained regularly, but they had never been given a maintenance schedule, so there were times when moisture got into the compressed air line and ruined an otherwise excellent finish. Also, neither the supervisor nor any of the painters had ever opened the moisture trap/filter to clean out the ceramic filter. Admittedly, it took brute strength to unscrew the filter and we were afraid that the entire device would break apart into small pieces, but we prevailed and to everyone’s surprise several grams of rust and dirt fell to the floor when the filter was opened. One painter proudly told how he had been suspicious when he recently saw small bits of rust ruin his finishes. Rework of the damaged area took a full morning because he had to mask, sand, wipe clean, prime, and topcoat the surface. What a waste of time and money! Why
SPBAV GUN CLEANING
Finally, we reviewed spray gun cleaning techniques. The Aerospace NESHAP is specific about the four methods by which a spray gun may be cleaned. Failure to observe the correct techniques can cause the company to be fined $10,000 per incident. A pressure pot that was ready to be cleaned was used for the demonstration. Because painters, like most of us, are competitive, we took bets on who could use the least amount of solvent to flush out the fluid hose and clean the gun and pressure pot. A veteran painter volunteered to demonstrate his skills. To flush coating from the fluid hose he showed the others the technique for blowing paint back into the pressure pot. We warned the painters in no uncertain terms that this technique was never to be used when cleaning the fluid hose of an airless or air-assisted airless gun. Next, he removed the existing dirty plastic liner and replaced it with a clean one. Using less than Yzgallon of solvent, he was able to thoroughly clean both the fluid hose, the fluid tube under the lid of the pressure pot, and most of the internal surfaces of the spray gun. While 1/2
Figure 3. Plastic liner with dry paint.
gallon of cleanup solvent might seem to be excessive, this shop typically used 3/4to 1 gallon to perform this function. Both the supervisor and the facility’s environmental manager were delighted that their own painter could teach his colleagues another method for minimizing hazardous waste. We allowed the paint in the dirty plastic liner to cure overnight and then knocked the cured paint off the walls and bottom of the liner onto a piece of masking paper on the floor (see Fig. 3). Consequently, no solvent was used to clean the liner. This one-day, onsite training was augmented with two days of hands-on demonstrations of painting techniques to improve transfer efficiency. Details of this section of the program will be discussed in a future paper but can also be found at www.ronjoseph.com/trainingprograms.htm. In summary, painter training is not only extremely valuable to improve the “bottom line,” but it can be fun. Most painters enjoy learning something new, especially if it enables them to do a better job. Some old-timers often take little interest, but over the past years I have had success even with the most hardened painters for whom it was said “you can’t teach an old dog new tricks.” I guess you can. BIGGBAPHV
Ron Joseph is an independent coating consultant in San Jose, Calif. He can be contacted by E-mail at [email protected]. MF
ABOUT NERY FACET OF THE MRAL FINISHING INDUSTRY. Call for a FREE Book List: Fred Freyer 212-633-3199 40
Metal Finishing
Pays off
by Ron Joseph Ron Joseph & Associates
Inc., San Jose, Calif:
A
nyone who walks into the average painting facility knows how much dirt and overspray surrounds the paint shop. Engineering managers who know every detail of their NC machines, robots, and high-tech welding operations often take the long route around their paint shops because of this low-tech, dirty, and sticky eye-sore in the middle of an otherwise immaculate fabrication shop. Money is often available for training the sheet metal folks, but somehow the budgets are “coincidentally” depleted when the subject of painter training comes up. This paper provides an insight into the advantages that can be reaped by training the paint supervisors and painters. Such training can be unsophisticated and relatively inexpensive, but there is always a lucrative financial payback. Rather than cover a comprehensive training agenda, this paper will provide only a glimpse of the issues that were covered when I recently visited an aerospace painting operation. EFFECT OF THE SPRAYBOOTH
ON PAINTING
DEFECTS
One of the most troublesome areas in a painting facility is the spraybooth. An abundance of paint defects and failures is generated here simply because of poor spraybooth design and maintenance, and an understanding of how a spraybooth works. Typical problems that occur in thousands of facilities each day include dust in freshly painted finishes, overspray, orange peel, blushing, cratering, dry spray, and more. In large painting operations the cost to prevent or minimize these defects probably exceeds tens of thousands of dollars per year. Yet, in most cases, it is fairly simple to address the problems and very little, if any, capital outlays are required. Over the past 15 years I have discovered to my surprise that most engineers, supervisors, and painters don’t have a clear understanding of how their spraybooths function and why a uniform airflow is so important. It doesn’t take a rocket scientist to appreciate that turbulent airflow in a booth can cause dust and overspray to settle on freshly painted surfaces. A 38
few months ago I visited an aircraft facility in which an aircraft is positioned with its tail toward the filters and its nose pointing to the double swing doors at the entrance of the booth. Painters were terribly frustrated. When they painted the tail (closest to the exhaust filters), overspray was carried to the front of the booth and settled on the nose. This wouldn’t have been .too serious except that the tail was painted with gloss white polyurethane and the nose with a gray. Now perhaps you can better appreciate their frustration. The cause of the problem was poor airflow through the booth. Not understanding how a spraybooth functions, the painters were not careful to properly shut the double doors, and the large gap between the leaves caused unnecessary turbulence. The booth had an air make-up system and the incoming airflow rate didn’t match the exhaust flow rate. In fact, the exhaust was pulling so much air that the personnel access doors on the side of the booth were difficult to open. This implied that the booth was operating under severe negative pressure. On occasion someone would enter or leave the booth while painting was under way, and that caused no end of additional turbulence. On one occasion I watched as small bits of masking paper and masking tape lifted clear off the floor and flew directly into the freshly painted fuselage. As a result of this experience I asked the paint manager if he would allow me the time to take the painters into their break room for a short impromptu training session. Fortunately, the supervisor joined us and within 45 minutes I had explained how their spraybooth functioned and why they were experiencing so many problems. Thereafter, they immediately implemented a rule that the double doors were to be properly shut at all times, and the broken seals between the doors were to be replaced. The window in the access door was thoroughly cleaned of a thick layer of overspray so that people on the outside could now see when painting was taking place. Nobody was allowed to open the door until the painters on the inside gave the okay. The imbalance of airflow between the supply and exhaust plenums was largely due to poor engineerMetal Finishing
Figure 1. Manometer
without
fluid.
ing and the fact that the booth was old and needed a thorough overhaul; however, there were other factors that only worsened the situation. Baffles on the supply plenum had been rotated on a random basis in the hope that this would lessen the turbulence. Some baffles were missing. The exhaust filters at the other end of the spraybooth were plugged with overspray, and a filter change was long overdue. Once again, I took the paint supervisor and his painters aside and explained why it was so important for no one, other than an air ventilation technician, to touch the supply baffles. As to the exhaust filters, I showed them that there was no red dye in the manometer attached to the outside sheet metal of the booth (see Fig. 1). Without the dye they could not possibly know when to change the filters. In the presence of his colleagues I arranged for the lead painter to replace the fluid. He then zeroed the manometer, and we discussed how to determine when it was time for a filter change. There was no argument when I showed them that the first-stage roll filters had been so poorly suspended from the ceiling that overspray-laden air could bypass the first stage and quickly foul the second-stage pocket filters, at $36 each (see Fig. 2). In less than 5 minutes they learned the proper technique for changing the filters with the result of improving capture efficiency and extending the life of the second-stage filters. To my great pleasure everyone showed real interest. ORANGE PEEL DEFECTS
The typical “orange peel” paint defect really bothered them because no matter how diligent the painters were at setting up their HVLP spray guns they March 2002
Figure 2. Poorly positioned
filters.
could not eliminate the problem. One glance at the compressed air hose and fittings explained it all. They had three quick disconnects (QD) in their 1004% long air hose; one at the regulator on the spraybooth wall, one at the handle of the spray gun, and the third connecting two 50-R hoses to make a single long hose. To add insult to injury, the air hose was y4 in. in diameter. Again, the problem was easily solved after I took another few minutes of their time for training. They were shown how pressure drops occur in a long hose, whether air or fluid. Using some pressure gauges we experimented with the existing y4- and a new %-in. hose. The QDs on the regulator and between the two 50-R hoses and all remaining G-in. fittings were replaced with %-in. connectors. To their delight they watched as the pressure differential between the regulator and the handle of the spray gun decreased. Finally, they could get adequate compressed air to the spray gun and wave goodbye to orange peel. But not so fast. Because the facility is subject to the Aerospace NESHAP, they are obligated to demonstrate that the atomizing air pressure never exceeds 10 psig. Fortunately, I had a suitable replacement cap and pressure gauge for the Binks Mach 1 HVLP gun, 95P cap, and was able to demonstrate how to keep the gun in compliance with the NESHAP. Some of the more enthusiastic painters wanted to check their own respective guns for compliance, and one painter who was using a DeVilbiss HVLP gun asked his supervisor to please purchase an appropriate cap/gauge for him. The training was a success. Not only did the 39
painters all but eliminate the orange peel defect, they were now aware of compliance issues and could prevent an unwanted Notice of Violation. WATER SPOTS
did the painters occasionally have water spots in their finishes? They were all aware that the moisture trap needed to be drained regularly, but they had never been given a maintenance schedule, so there were times when moisture got into the compressed air line and ruined an otherwise excellent finish. Also, neither the supervisor nor any of the painters had ever opened the moisture trap/filter to clean out the ceramic filter. Admittedly, it took brute strength to unscrew the filter and we were afraid that the entire device would break apart into small pieces, but we prevailed and to everyone’s surprise several grams of rust and dirt fell to the floor when the filter was opened. One painter proudly told how he had been suspicious when he recently saw small bits of rust ruin his finishes. Rework of the damaged area took a full morning because he had to mask, sand, wipe clean, prime, and topcoat the surface. What a waste of time and money! Why
SPBAV GUN CLEANING
Finally, we reviewed spray gun cleaning techniques. The Aerospace NESHAP is specific about the four methods by which a spray gun may be cleaned. Failure to observe the correct techniques can cause the company to be fined $10,000 per incident. A pressure pot that was ready to be cleaned was used for the demonstration. Because painters, like most of us, are competitive, we took bets on who could use the least amount of solvent to flush out the fluid hose and clean the gun and pressure pot. A veteran painter volunteered to demonstrate his skills. To flush coating from the fluid hose he showed the others the technique for blowing paint back into the pressure pot. We warned the painters in no uncertain terms that this technique was never to be used when cleaning the fluid hose of an airless or air-assisted airless gun. Next, he removed the existing dirty plastic liner and replaced it with a clean one. Using less than Yzgallon of solvent, he was able to thoroughly clean both the fluid hose, the fluid tube under the lid of the pressure pot, and most of the internal surfaces of the spray gun. While 1/2
Figure 3. Plastic liner with dry paint.
gallon of cleanup solvent might seem to be excessive, this shop typically used 3/4to 1 gallon to perform this function. Both the supervisor and the facility’s environmental manager were delighted that their own painter could teach his colleagues another method for minimizing hazardous waste. We allowed the paint in the dirty plastic liner to cure overnight and then knocked the cured paint off the walls and bottom of the liner onto a piece of masking paper on the floor (see Fig. 3). Consequently, no solvent was used to clean the liner. This one-day, onsite training was augmented with two days of hands-on demonstrations of painting techniques to improve transfer efficiency. Details of this section of the program will be discussed in a future paper but can also be found at www.ronjoseph.com/trainingprograms.htm. In summary, painter training is not only extremely valuable to improve the “bottom line,” but it can be fun. Most painters enjoy learning something new, especially if it enables them to do a better job. Some old-timers often take little interest, but over the past years I have had success even with the most hardened painters for whom it was said “you can’t teach an old dog new tricks.” I guess you can. BIGGBAPHV
Ron Joseph is an independent coating consultant in San Jose, Calif. He can be contacted by E-mail at [email protected]. MF
ABOUT NERY FACET OF THE MRAL FINISHING INDUSTRY. Call for a FREE Book List: Fred Freyer 212-633-3199 40
Metal Finishing