painting process Question
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Posted by: kimmyneutron

11/24/2005, 19:58:56

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for outdoor applications (cranes), would a process consisting of: sandblasting, zinc phosphating, powder coating be cost-effective and long lasting?

what other suggestions do you have?
I'm a student (3rd year Aerospace) working in the production engineering department. Current project is the design of a paintshop.
Thanks!







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Re: painting process
Re: painting process -- kimmyneutron Post Reply Top of thread Forum
Posted by: Michael_D_Patterson

11/28/2005, 11:54:20

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Check out PPG's industrial, They might be able to help you pick some appropriate applications for your paint shop. I have found them to be extremely helpful in answering my questions quickly. In general for large items that you can sandblast, your approach is labor intensive but effective. For fresh, clean parts, there are also self-etching primers that can be used which can eliminate the sandblasting process.

I think powder coating would be good for an application on smaller parts ("small parts" is a relative term but think of them as the size you can fit YOUR curing oven) that see environments like chemicals or liquids that are out-gassing or spilling/leaking: oil, coolant and salt water for instance. Power coating is resistant to more costic liquids than epoxys or urethanes are but not for limited periods of time (which you would have to determine). Don't forget that powder coating requires about 400F cure temperatures where epoxy and urethane can air dry. I think PPG can set up matching colors for powder coatings and epoxy/urethane combos. If extremely large items are to be painted and cannot be put in an oven then you need something catalyzed.

Let us know what you come up with.

Michael






Modified by Administrator at Mon, Nov 28, 2005, 12:14:35

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Re: painting process
Re: Re: painting process -- Michael_D_Patterson Post Reply Top of thread Forum
Posted by: kimmyneutron

11/28/2005, 18:32:01

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Thanks Michael and everyone else who is helping me.

Yesterday I actually took time to visit the current situation, and discovered there is a small sand blasting cabin, and currently all parts are being hand sprayed and left to air dry. The area is about 6m in the longest side and about 4 on the shortest. It's quite rectangular.

The company might be making a big investment, so I was thinking of a conveyor system with liquid paint, probably handsprayed, that encompassed an area of maybe 20m by 10 m.







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Re: painting process
Re: painting process -- kimmyneutron Post Reply Top of thread Forum
Posted by: kelly_bramble

11/27/2005, 08:41:51

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For a large structure, no, powder or powdered coatings are not cost effective. I can't even imagine the facilities required to powder coat large structural parts.

In general, a realy good industrial paint is probably the best cost effective soultion.






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Re: painting process
Re: Re: painting process -- kelly_bramble Post Reply Top of thread Forum
Posted by: kimmyneutron

11/27/2005, 18:25:38

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thanks for the reply.

i'm wondering how big the parts that you talk about are??

most of the parts that go through our paintshop are no bigger than about 2m in length and let's say.. a 30cm width at the widest?

would powder paint be useful then?

thanks







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Re: painting process
Re: Re: painting process -- kimmyneutron Post Reply Top of thread Forum
Posted by: randykimball
Barney
11/27/2005, 19:41:52

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Powder coat is cost effective for parts that will fit the facility doing the process. They are also even more effective for part with complex shapes hard to get to with a spray unit.

Items that are large and exposed to outside natural harsh conditions do well sand blasted, or well cleaned and skuffed, then coated with a high end urethane product system. These are often a two to three step spray on application system. There are other epoxy or acyrlic systems as well that perform in harsh conditions. Modern spray on systems have a tough but high bonding and interlocking structure with good UV protection. This makes them last and handle rough treatment. Recent years have seen vast improvements in these products.




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Re: Re: painting process -- randykimball Post Reply Top of thread Forum
Posted by: Gary Kemp

11/28/2005, 14:23:22

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MIL-STD-186, 208/407/448 is used on military vehicles. 208 is chromate conversion coat (MIL-C-5541, CLASS 1A) used for aluminum. It would be "210" phosphate coating (TT-C-490, TYPE 1) (ZINC)for steel. The 407 is epoxy primer good for both materials. The 448 is green 383 in accordance with FED-STD-595. Other color options are available. If you pull the 2 specs MIL-STD-186 and FED-STD-595 along with specific additional specs identified within them you may obtain some valuable guidance.






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Re: painting process
Re: Re: painting process -- Gary Kemp Post Reply Top of thread Forum
Posted by: dspindlersr

12/01/2005, 19:21:03

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Most equipment manufactured for constant, long-term outdoor exposure is painted with high-reliability paints. The best process would involve: (1) sandblast to white metal, (2) apply 1 - 3 mils of 2-component epoxy primer, (3) apply 1 - 2 mils of 2 component Urethane top coat. Follow the manufacturer's directions to the letter. For the best information go to the companies that manufacture these type paints, such as Ameron, PPG, Valspar and others.

Urethane coatings, when used alone, won't give the performance that the epoxy primer/urethane top coat systems. The problem is long-term adhesion failure.







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