Paint process is painstaking

WHAT DO YOU get when you take the “t” out of paint?

Pain.

There frequently is pain in the paint process.

“You say it all the time: ‘There's so much pain in just trying to put a little bit of plastic on a piece of metal,’” said Greg Stemley, who has been a senior manufacturing engineer, operations manager, and engineering manager in paint during his career at Harley-Davidson.

That's one of the four truisms he listed during his presentation, “Paint Systems in Manufacturing.”

The others:

  • “If someone professes they're an expert, stop listening. You have to be a metallurgist and an expert in aerodynamics and chemistry. It's just hard to do all that and know all that.”

  • “Let's see what we can see. In lean, you have to directly observe. We must go out and find out what's going on. Don't do it from your desk or somebody else's eyeball.”

  • “Paint is a funny thing, and sometimes not funny.”

Stemley said process control is one of the keys to success.

“If you don't have good process control and you're troubleshooting for a day and you find out somebody isn't following the process, boy, it's frustrating,” he said. “Back to basics. Blocking and tackling.

“Metals have gotten worse. We have multiple suppliers of metal. In order to make a good product, we have to be able to treat that metal right.”

He said everyone must know the process and its capabilities. If not, they won't know what the best quality is. Management must lead from the top down, and the process has to be implemented from the bottom up.

“We had a delamination issue and sent our product back to our paint supplier and asked him to do testing,” he said. “He said, ‘Everything's looking good.’ We sent it to a secondary lab because it didn't make sense to us. We found out our crystal size and coating weights were wrong. It was causing too-big crystals and we were fracturing our paint.

“What's important? What's hurting your industry? A lot of times we'll ask another paint supplier to do something for us. If we don't think we're getting the right answers, we check with someone else. We do some field testing. We have salt spray and humidity chambers. We do it mostly when we have new products.

“I'm big on process control. We do a lot of it. We understand that if we can control our processes, we're going to get the best product. We do it by KPC (Key Product Controls) and KCC (Key Control Characteristics). With KPC, we have product specifications on how much it's costing. With KCC, we want to make sure the oven isn't fluctuating and that the temperature, pH, and conductivity are staying in the right range. If I have a stage that needs to be 140 degrees for pre-treatment and it's running at 120, I don't know if I'm going to get a good product that day.”

Other topics

He also talked about:

  • Work instructions.

    “If something's going wrong, the first thing we do is grab the work instructions and ask the operator. If they're not following the process, then we have problems. It's very important for the operator to know exactly what you want him to do. Word of mouth is not good enough, especially if Joe's working the first shift and Bob's on the second shift and Frank's on the third shift. Dissemination of information will get tainted.”

  • Visual aids.

    “We're huge into it. A picture's worth a thousand words. Let them see what you want them to do.”

  • Check sheets.

    “Every job is on a check sheet. We break it down by hour: ‘This is what we want you to do from 7 to 8. This is what we want you to do from 8 to 9. This is what we want you to do from 9 to 10.’ He might say, ‘Well, I didn't do that because I had to go fix this.’ Why are you behind schedule? Each check sheet has a task and each task has a work instruction. Don't minimize process control.”

  • Internal audits.

    “We check to see if they're following their work instructions. We bring in someone from another department. They're a check and balance for us. It's not a bad thing.”

  • Wash, clean, rinse, and dry.

    “Make sure you get your paint supplier involved up front. We ask them to spec out our own equipment. We tell them our specs and work with them on filtration and the size of tanks. The drying and rinsing are very important. Flash rusting's a bad thing. If you don't get your product totally pre-treated, you could have bad product coming out.

“Are you just washing it, or do you have to clean it? It depends on your product and which processes are used before you get the product. It's two different things. Our pre-treatment is 11 stages. Our salt spray specification is 350 hours. Washing removes contaminants from the manufacturing process. If you don't pre-treat it right, I don't care what you do — you're not going to get a good product. You guys are trying to fix your paint problems. Fix them up front.

“It requires cleaning chemical or aqueous solution. We have risers and nozzles set for different pressures. We have multiple risers in a stage with hundreds of nozzles and we're looking for impingement on the product. Look at your nozzles and risers. Some stages are set at 40 psi, some 20, some 30. It depends on the process. Temperature is also important.

“Specified time and temperature are hugely important. You can't monitor each riser or each nozzle, but if you can monitor the header, you know at least you have a fighting chance. But if you don't check the nozzles and risers and they clog up, it doesn't matter. It could be one nozzle spraying and 10 clogged up. That should be part of your process control and work instructions. Do you look at the scale? At the buildup? Do you have the right filtration?

“Rinsing is not always required, but it is recommended. Most rinses involve some sort of chemistry, either water or solvent. Your paint suppliers and pre-treatment suppliers will help you.

“Drying is very key. Do you have bleedout or runout? Basically, you get some entrapment of your pre-treatment process and then when you put your topcoat on, it goes in the oven and bakes and starts bubbling out. Next thing you know, it's underneath. It looks like dirt. It's important to dry.”

  • Versatility of equipment selection.

    “I can remember in '87 somebody came up to me and said, ‘Greg, I've got a great product for you. I want you to work on a water-based system. That is the way this country is going. We have to get the equipment ready for these people because that's where they're going.’ Eighteen years later and it hasn't changed. Some people do it. Powder's probably making as big a mark as water-borne. It's getting more competitive in color and choices. Impact resistance and durability are key advantages.

    “They have developed equipment for powder that almost acts like a liquid. You can also robotically apply it. It's not that expensive. You can control your processes, too.”

  • Touchup.

    “You spend all this time and money in a product and it comes out with a couple of defects. Get a touchup process in there. Get a repair process guy. Talk to your paint suppliers. Try to minimize throwing it away and stripping it. You've lost all that money and then you have to do it again. If you don't have a process, find one. It's a huge cost-saver for you.”

  • Lean manufacturing.

    “Paint shops are not easy to lean-out. Just understand that. Environmental regulations eliminate some of the old easy-to-use coatings. Some of the stuff we used in the past we can't use or are not going to be able to use in the future. Make sure you keep that in mind as you're trying to lean-out your system.”

  • Cleaning.

    “Cleaning is huge. Don't minimize it. We shut down early and give everybody a broom and a rag and tell them, ‘Clean up your work area.’ It does two things: keeps dirt off parts; and keeps the mentality in the shop that this is important.”

TAGS: Fabrication
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