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Painting enclosure with polyester or epoxy powder coat?

V

vmipacman

Cast Iron
Joined
Nov 21, 2014
Location
Virginia, USA
Picture repainting a vmc enclosure. Panels already disassembled and taken over there. My powder coated says I won’t notice a difference, and he has the polyester paint in stock but needs to order if I go with the epoxy powder. Getting to this point is a real pita. I only want to do this once. So will I notice a difference?
I’m going off the assumption that the epoxy powder will have better abrasion and adherence characteristics.
Thanks
 
You won't like this I am sure and I'm guessing your powder guy will like it even less but if it was me I would have it sprayed with oil based industrial enamel not powder coated. The tree huggers and their anti-VOC campaign in conjunction with the bean counters is who is really behind the stampede to powder coat everything, in my opinion. When I see automobile finishes powder coated I'll be a believer. As far as the difference between epoxy and polyester powder coating, it depends on how much money you spend an expensive poly will beat a cheap epoxy and vis-versa.
 
tmittelstaedt said:
You won't like this I am sure and I'm guessing your powder guy will like it even less but if it was me I would have it sprayed with oil based industrial enamel not powder coated. The tree huggers and their anti-VOC campaign in conjunction with the bean counters is who is really behind the stampede to powder coat everything, in my opinion. When I see automobile finishes powder coated I'll be a believer. As far as the difference between epoxy and polyester powder coating, it depends on how much money you spend an expensive poly will beat a cheap epoxy and vis-versa.
Click to expand...

I think you are wrong. I did a major repair of a SB 1308 almost 20 years ago and I powder coated the base cabinet at that time. The cabinet not only supports the lathe bed, but acts as a chip pan as well. The lathe has been is continuous use since. The powder coat is in perfect condition even in the chip pan. I know of no paint that will stand up to 20 years of chips and chip cleaning.
 
Urethane man... Polyurethane is what you want on your machine. Find a paint burn off shop in your area and start there. Then powdercoat. Panels don't even have to be cleaned. And don't forget the stationary sections of your way covers while you're at it.
 
The powder coater should blast the surfaces clean first. Then that stuff is applied with potential difference and baked on.

If you ever tried to clean a piece that was powdered then you would know that it is the way to go. But typically large flat panels are not powder coated.
 
rons said:
The powder coater should blast the surfaces clean first... ...But typically large flat panels are not powder coated.
Click to expand...

I've had two enclosed machining centers that have been fully powder coated. Every panel on them including the coolant tanks and the top fixed way covers as I mentioned earlier. The powder coat shops in my area may have a blasting cabinet, but I don't believe any of them have full on sandblasting rooms as it were. Sandblasting is great for small, cabinet size stuff of heavy section, but you'd never want to blast sheet metal panels for two reasons. One is unless they're fairly heavy gauge they'll warp, and two it would cost you a fortune. Still the problem remains you don't powder coat over old existing paint. That's where the burn off comes in so handy. No prep other then removing dents. Even grease, dirt and old coolant are no problem. Paint burns off and the after treatment which is some kind of pickle or acid or etching bath makes them for the most part hang and paint ready. Honestly I learned about paint burn off from the owner of the powder coat shop I go to. The cost has always been very reasonable. Especially when you ad in the little to no prep aspect of it all. So there ya go. Different experiences for different folks I guess.

BTW - Epoxy is prone to chalking over time. That may be more of a problem outdoors, but just sayin.
 
I’m going to go with what they have in stock. It’s a Tiger 49 series polyester. The better powder would have been epoxy 69 series. Unfortunately it’s not stocked in the color that best matches. This 49 series I hope will stand up to many years worth of use.
I brought over about a dozen panels about 4ft x 6ft. All the panels will be blasted and powder painted. Not real cheap.
I asked about burn off and they made it sound like that would be far more expensive. It’s all about what they are used to and setup for. The sheet metal is pretty heavy gauge with stiffeners. Probably 12 gauge.
I would have opted for ordering the epoxy p-coat, but that path got more difficult when the only option along that line was a custom mixed batch. Sure, where there’s a will theres a way but my p-coater wasn’t enthusiastic.
 
Just for the hell of it I looked up what I payed for burn-off on my last machine rebuild. This was a full size fully enclosed VMC with a pallet station. Six carefully stacked pallets worth plus the coolant tanks. 1000 bucks even. Included pickup at my dock and delivery to the powder coat place.

I washed the panels down anyway before letting them go. Couldn't help myself, but I did have to get them clean enough to see what and where they might need bodywork. The burn off guy insisted though that dirt and grease didn't matter.

Later when I went to the powder coat shop to organize the parts and stack according to color, I thought the surface looked great to receive paint. A little knock-off of loose paint bits or sealants here and there and that was it. The burn off also helps to get old oils and coolant out of the seams in the sheet metal. Which if not done previously can come to haunt when the powder coater puts the parts in their oven at 400 degrees and they start seeping then. In cases like that they usually have color matched spray cans for a little touchup.
 
That’s a deal! I’m hoping to keep it around 2500 Total for sandblast and powder. It’s T&m but my guy will generally tell you worst case. My powder coater is pretty picky, really concerned about quality so he must prep and coat or he’s really reluctant to touch it. He re sandblasted some stuff I brought him once, it prob didn’t take but a once over but it has to go through the process. But I trust his work, they are 5 min away and I try to be loyal since they do the best they can when I’m in a hurry.
 
13engines said:
I've had two enclosed machining centers that have been fully powder coated. Every panel on them including the coolant tanks and the top fixed way covers as I mentioned earlier. The powder coat shops in my area may have a blasting cabinet, but I don't believe any of them have full on sandblasting rooms as it were. Sandblasting is great for small, cabinet size stuff of heavy section, but you'd never want to blast sheet metal panels for two reasons. One is unless they're fairly heavy gauge they'll warp, and two it would cost you a fortune. Still the problem remains you don't powder coat over old existing paint. That's where the burn off comes in so handy. No prep other then removing dents. Even grease, dirt and old coolant are no problem. Paint burns off and the after treatment which is some kind of pickle or acid or etching bath makes them for the most part hang and paint ready. Honestly I learned about paint burn off from the owner of the powder coat shop I go to. The cost has always been very reasonable. Especially when you ad in the little to no prep aspect of it all. So there ya go. Different experiences for different folks I guess.

BTW - Epoxy is prone to chalking over time. That may be more of a problem outdoors, but just sayin.
Click to expand...

Sun UV does that.

The powder coat place I last went to had a huge sand blast enclosure that had done a truck frame for a 18 wheeler cab. Not enclosure but house.
 
The powder coat turned out great. I hope it lasts a long time!
For electrical enclosures that can’t easily be removed and not very easy to tape and paint. What do you think of vinyl wrapping them with the paint color like a car? Bad idea?
 
vmipacman said:
The powder coat turned out great. I hope it lasts a long time!
For electrical enclosures that can’t easily be removed and not very easy to tape and paint. What do you think of vinyl wrapping them with the paint color like a car? Bad idea?
Click to expand...

Interesting thought. The stuff holds up on boat hulls, I can't imagine a machine enclosures being worse than that.
 
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