Small scale powder coating line for occasional use
Does anyone here do small scale powder coating. Were looking for a through put of about a couple of hundred to a thousand brackets a month. Brackets are tiny sheet metal components. Sub 2" square but of at least 12 diffrent sizes - shapes. So far the commercial powder coaters we approached have not been interested - too costly due to the fiddly little nature of the bits. Add in the travel time of taking them there - brining them back and it gets hideously costly fast for what they are.
Currently we aerosol tin spray them with primer then top coat. There all the same colour - satin black (no option of changing finish, can't plate already been discussed to death with customer). There's adhesion issues and were going through spray tins like no tomorrow! We need to get away from wet painting them, its just not working. Its messy, smelly and slow. Drying times a major pain!
Due to the nature of what the parts are the painting cost is always going to be a significant part of the bit coast and this is factored in. Currently were doing ok money wise on them, it just would be nice to get a better result for the amount of effort that gets put in.
Racking and unracking them is not a issue labour wise. Its a 2 hour round trip to the nearest powder coaters, even if they would show some interest! Hence there's a lot of time lost regardless of them not wanting to do them (there all set up for lower qtys - larger items). There price is currently about triple what our costs are to make - paint them ourselves. Our customer would not accept that kinda increase.
Hence were exploring the option of doing these in house. What were ideally after is a basic - simple set-up that can ideally live on a pallet that we can stick out of the way when its not needed. We don't even need a high speed process. If it took a 8h day to run say 500 that currently would not be a major issue. Equally we don't even need perfect results. Also the parts are all standardised - won't be changing hence we could run a lot more less frequently if that works out more efficiently.
So does any one here do this sort of coating and what's the pit falls? Equally there's a lot of progressively larger parts we make that also get coated. Hence there's potential to grow this significantly with just our own work. Powder seams dirt cheep for the coverage and energy costs ain't much for the sizes were considering here.
one idea is to dip them. a paint maker can make up a water borne paint that will dip well. This is a real cheap way of doing small parts, kind of messy. but it works well and you can get finishes at least as good as your current rattle can process. I have seen fairly large parts for material handling machinery done with dipping, no primer just one dip, and air dry on a chain conveyor running around their plant ceiling, after the first few feet it stops dripping. they say it is an "agricultural grade finish". I had a part about a foot long that was getting expensive to powder coat and was supposed to be made in large quantities. So I started to set up a dip line, 100 foot of light chain conveyor where we would first dip them in primer and load up the conveyor, wait until dry and then redip.
i would think dip painting as suggested above would be less costly by far compared to the present method.
the powder coating isnt all that cheap to set up,there are do it yourself kits that use a househlod oven,but the quantity you require would need a large industrial oven.
eastwood is one company that carries small powdercoating setups.
dip line would produce less airborne matter than spray,the water base products still need a solvent base primer to be durable as well as a clear coat.i dont put much faith in single stage water base paints-yet.
I don't know if you have the equivalent of that Co we are not to mention (HF), but look here: Powder Coat Oven 500 USD for in 18" cube inside dim oven. Here: 16 Oz. Powder Coat Paint, Matte Black for a 70 USD powder gun, and 4 USD per pound of powder.
600 USD you could give it a try. OR,you could look into a better system, and I know they are out there, but way more expensive. Try this and see if you can make money.
According to this: Powder coating - Wikipedia, the free encyclopedia Wiki article, the powder is reclaimable and reusable, which you can't do with that rattle can.
I know nothing about it, the only time I ever saw it done was at the GE Factory in Louisville, Kentucky, on washing machine and electric range panels.
One feature of it, I think, is that being electrostatic, you could devise racks to hold however many parts you can, and don't have to orient the piece to aim your rattle can nozzle at. It wraps itself about the piece.
You mentioned in your opening post maybe 1 thou per month. If that is over the month, rather that 1 thou at a time, you would probably be able to coat the day's run during that day.
With 10 minute cure time, and if you could make rack to hold, say, 20 pieces, even doing them all in one day would be 500 minutes, 8 hours, 20.
With those numbers, I'd think you should give it a try, and step up if you need to.
18 X 18 X 18 means you can do the thing you call " a bit larger".
There is no way you would want to run a thousand parts a month using an old household oven.
And the capital expense of setting up a decent sized powder coat oven and spray booth is probably between ten and twenty grand, minimum, for a 4'x4'x4' size.
You dont say what your parts are worth, or what prices you would be quoted by powdercoating houses, but I cant imagine you are actually getting paid enough to set up a powder system.
I used to drive 2 hour round trip all the time to the powder coaters- just pay a ten dollar an hour part time employee to do that- or dont you have teenagers in the UK?
I sent similar sized parts out to a shop that had probably invested at least a quarter million dollars in their powder coating setup, not including building and forklifts and pallet racks. So they had an automated overhead conveyor system, where the parts were hung on hooks, or for small parts, sub racks, and run thru a 5 step prepaint dip tank sequence, and then past 4 automated guns, and then thru a 40 foot or so infrared tunnel oven.
Their per part price, as I recall, was around a buck a piece for a pretty fancy color, less for matte black.
If you need the level of quality and toughness of powder, it makes sense to pay somebody like this.
If you can get away with dipping in enamel, then that should be cheaper to set up, and pretty easy to do. I would still consider an oven, though. I have used a variety of industrial paint shops over the years, and one common setup for batch painting of parts like that is a steel cart, maybe 2 feet wide, 6 feet long, and 4 or 5 feet tall, that has bars for hanging parts from, and that rolls right into an appropriate sized oven. You load the cart, spray the parts with either powder or wet paint, and roll the whole thing in to bake.
Just saw George's post- and, well, powder coating in quantity to commercially acceptable standards is a bit more complicated than that. I have probably sent several powder coater's kids thru private college, with the amount I have spent on it over the years, doing regular weekly loads to 3 or 4 different powder shops over a 15 year period, when I was doing small production work.
In reality, you need better guns, bigger ovens, with better, more controllable heats. 10 minutes is not realistic for most powder curing- depends on material, part thickness, and type of powder, but 20- 30 minutes is more common. Pretreat usually means sandblasting on hot rolled, you can get away with just chemical treatments of cold rolled, but cleanliness and prep is VERY important, and makes the difference between a saleable end product and rejects.
The paint does stick electrostatically, but it wont go down the alley and thru the door into the parlor- you still need to shoot from all sides. You need to rack the material free hanging, and that takes space- an 18" cube will realistically probably only hold maybe a dozen brackets, max, and with an hour turnaround time from racking, to spraying, to heating, to letting cool, you will be working 5 days a week to do that many parts with a setup that small.
And the stories of recycling powder are theoretical, to say the least- I have been around BIG powder shops since the late 80's, and never seen one that would bother with trying to recycle the stuff that missed- its just too easy to screw up and pollute the good stuff. In general, this is not like spraying from a can- there is a learning curve, and good equipment makes a HUGE difference in quality- I never dealt with anyone commercially who used a spray gun that cost less than $2500 to $3000 or so. If you screw up, the stuff is really on there, and usually requires baking in an oven at 1000 degrees or so BEFORE sandblasting it off- which means, on one dollar parts, there is 3 bucks of labor before you can reshoot- little stuff seldom gets reshot. One shop I dealt with, right by LAX, got the tube frames for Cobra cars air shipped in from Great Britain, and they powder coated those- and, if they screwed up, they would strip and recoat- but one dollar brackets- nope, you rely on experience to not screw up, cause they get binned if they dont turn out right.
This is a speciality subcontractor thing, not something you just can do in the corner. Unless your time is worth nothing, your volume is tiny, and you are flexible about quality.
Gotta stress were not after quality as such, just better than a half arss'ed spray job. Currently it now transpires that the boss has been taking these home and doing them at no cost to the customer. Something i did not know till 5 minutes ago. Hence i don't think im going to get any were on this after all. Shame because im pretty certain our customers end customers would definitely pay more for the quality on these. Equally even a half assed powder job would be a improvement on the batch of brackets i saw today :-( the brackets are part of a far larger kit of bits, hence even a significant cost increase would not add much to the kit cost.
Equally from the comments i am seeing above it sounds like if we could find a powder coater further afield who is set-up with a production line, not just a gun + rack and oven we could well be nearer the prices we need. And a quality beyond our wildest dreams! The parts are all made from either cold rolled plate or pickled and oiled. Will have to explore that further if this comes up again. There's certainly no way we could spend 2-3K on a gun there's just not enough demand in total to justify that. But spending £30 on a courier or so to send a heavy box of bits around the uk is a viable option! A cubic foot of box space would at best guess be at least 6 months supply of brackets!
The OP said up to a thou per month. That is less than 50 per day, unless they do a thou at one time per month.
Cool down time would not be a factor if they fabbed 3or 4 or more racks, and I don't know how many they could hang and do at one batch.
My point was, for 600 USD, if they have the equiv. of HF or Princess Auto, as I think they are known in Canada, they would not be spending much at all.
IF the part is acceptable with rattle can black paint, it should certainly be acceptable with home done powder coat. As to the Wiki, and the thin coating to tend to crinkle, some mfgs. like it, as it hides flaws in the finish of the material under it.
Cleaning, and the OP says it is cold rolled, could be done in large batches in a tumbler, cleans off any scale and oils.
I am not up on powder coat, so do and did not know it is directional, but I imagine there would be room between the pieces to direct the flow at all aspects of the parts.
I am not trying to put the powder coaters out of business, but he said, in his OP, that "There price is currently about triple what our costs are to make - paint them ourselves. Our customer would not accept that kinda increase."
"Racking and unracking them is not a issue labour wise. Its a 2 hour round trip to the nearest powder coaters, even if they would show some interest! Hence there's a lot of time lost regardless of them not wanting to do them (there all set up for lower qtys - larger items)."
"Currently it now transpires that the boss has been taking these home and doing them at no cost to the customer. Something i did not know till 5 minutes ago." Hell, if that's the way he feels about it, forget all about it. It is no skin off HIS nose, it shouldn't bother you.
Are you able to give an idea of what the parts are shape wise, to see how bad they would be to rack? And a rough current price?
I've a little two-man band powdercoaters near me, who is quite happy to take the fiddly jobs as the powdercoating is only one part of his business, so he doesn't mind if the oven isn't going 24/7.
I can ask him next time I swing down there for a rough price if I know what you're after.
Puttiing the ''politics'' of this case aside
I'm in the dipping camp Adam,........ you can dip a lot of small parts in an hour, all you need is a drip tray, hanging frame and wire hangers.
Quiick and cheeky dipping paint for UK guys - use Tractol machinery enamel, but thin it with cellulose thinnners - it flashes off much faster.
First of all, you need to powder coat some of these parts for a trial if you haven't already.
Because of the edge build, powder coating of small parts can be problematic espicially if clearances
or fit up is critical.
I wonder how many people who posted above have actually done any powder coating, because some of the things said have been just plain crap.
I bought an inexpensive PC kit from Eastwood and have been using it for the past couple of years to coat ad hoc parts for myself. The finish I achieve is excellent and the powders I use have a bake time of around 10-15 mins. I will normally PC as a first preference and paint only when I can't fit the parts in my oven. Any talk about having to spend hundreds of thousands of dollars on a dedicated PC line for your application is absurd. Virtually anyone on this forum would be, as a machinist, capable of fabricating an oven capable of maintaining the curing temperatures used by the powders and you could do batches of your brackets. Alternatively ovens that were used for other applications in a "past life" could be bought second-hand and used (eg commercial catering ovens etc). You've indicated that the finish doesn't need to be perfect, and the fact you're currently using rattle-cans testifies to that, so an "Eastwood quality" gun would be just fine. You will need to construct a basic booth to spray the powder (BTW yes the excess CAN be recovered if you begin with a clean area, but I don't ever bother, the powder is not THAT expensive!), a way to hang the parts and get to all the sides for even coating (these little guns don't like coating behind areas, nor getting deep into shielded areas if your bracket design involves them), and then transfer to the oven. I find the transfer from the coating area to the oven is the trickiest; the parts can't bang together or touch anything. Again, in your application I'd be looking toward ex commercial kitchen equipment that you could use, check out disposal type sales for some ideas. Ideally you'd want to clean and hang your parts on a rack, coat them, then wheel the rack straight into an oven. I don't think it would take a rocket scientist to design some sort of system where that was possible! I find the oven is normally the limitation in powder coating, if you can figure something out there, the rest is pretty easy. You will need the parts to be properly clean before coating. Of course this is no different to painting, but you can typically get away with a lot more with traditional paint than you can with powder coat. You can't PC parts that aren't properly clean and have any sort of expectation of an acceptable finish. You don't want to have to strip powder coat and redo it!!!!
Have a look at eastwood.com for the powder coating kits, I think for the application you mentioned they would be perfect. Eastwood ship to Australia so I'm sure they would ship to the UK too. You will need to find a source of powder locally, however in my experience that's not too difficult, especially if you don't mind buying larger quantities and storing it. At the small batch sizes you're doing you will be able to turn the air on the gun right down, as unlike a commercial powder coater speed is not as important, and even with a relatively low voltage gun you don't waste all that much powder so it goes quite a long way.
Hopefully that's of some help.
All of my "crap" comments clearly state I am talking about Commercial quantities.
And I stand by em.
Eastwood products are fine for a home shop. A thousand parts a month is not home shop.
I have not sprayed powder myself. But from about 1988 thru 1998, I probably sent 2 to 3 truckloads a month to the powdercoaters. I powdercoated thousands and thousands of parts- well over a thousand chairs, alone, in that time. A couple thousand soapdishes, similar in size to these brackets, and projects where each piece was 20 feet long. I still send out some powdercoating, although much less. I have worked with some of the biggest powdercoaters on the west coast. I do have just a bit of experience in this subject. I have seen a lot of possible things go wrong, even from very experienced shops, mostly to do with inadequate prep. The better shops I worked with sandblasted everything, just as a matter of course, because it was cheaper for them to have every part right than to rework even a few. When you are doing it for money, different standards apply.
And I still say, for reliable, repeatable, commercial quantities, you need a good gun, experience, a bigger oven than a recycled kitchen oven, and dip tanks for cleaning.
I did not say the OP needed a quarter million dollar automated line- I said it would be cheaper to send his parts to somebody who has one.
The biggest issue with powder coating it that it gets everywhere, like throwing a handful of flour into a shop fan. It does take some practice, but it is doable. If you have time you can build an oven. I built a 48" x 36" x 24" electric oven for $ 700, took me a few weekends. If you want to try it, get the dual voltage Eastwood kit, and a cheap toaster oven to try. Worst case you are out a few hundred. I think I would try a paint dip first, going to be less messy.
I've no doubt that huge amounts of $ can be thrown at powder coating, that's true of many things, what do they get for Rolex's or Ferrari's? but....
In the pic below, the frame was rattle canned primed and painted black, while the octagonal green thing was powder coated. The frame has nicks all over but the green thing, where all the action is, has no hint of nicks anywhere. My conclusion: This is good powder coating.
I built it in a friends shop in Mesa Arizona and when finished, (frame already rattle canned) he asked if I'd like it powder coated. I really didn't care, it's like an engine stand but said OK.
I wish I could remember where he got the spray gun, attending electricals and powder, it was a well known auto DIY equipment supplier, (something with "wood" in it?) and I've no doubt that the gun cost closer to $100 than $2,500.
The oven is a rectangular wooden box about the size inside of a large refrigerator, front door like a refrigerator, same construction as box, with door hinges. There is board insulation between the wood and the "fire".
The "fire" is a kitchen range oven, (might be a range top?) electric element lying in the bottom.
I'd be surprised if John has $100 in it, including the repurposed range timer. He has little sockets on the wall that hold 1/2" EMT, (light electrical tubing) at any chosen interval. Lotsa' little parts, less big ones. Cheap rebar tie wire fits between the EMT and part.
For the stated purposes of the OP, I can't imagine that throwing additional $ at it would make it more suitable. If I'm wrong and your last name is Boeing or Ford, do the high-roller thing if it blows your dress up. My friend John doesn't get their taxpayer provided subsidies but he does do good powder coating. He does work for ASU, Aeromotive lab, Mesa AZ and the prof's like shiney/pretty/durable.
Private note: John if you see this, please PM me, thank you.
A paint dip is as yet a unexplored option. For these it may well still be acceptable quality wise. Problem is the previous supplier of these and the rest of the parts we make for this customer use to dip everything. That was not good enough on a lot of the other parts. Hence the real idea behind exploring the powder coat option is that it would be darn near a unlimited venture, ie a lot of potential growth - keeping a lot more in house. Dipping would not be. The brackets are all low tolerance simple bends - punches out of 1mm mild steel. They are all under a 2" cube sized part when finished ready for painting, Equally they all have 3/16" or bigger holes that would lend them to hanging.
Pretreatment especially degreasing is and will probably remain the biggest hang up and why this idea will probably never turn into reality. The larger items we would also like to coat in house in the future are manderal bent and punched tubes. They use a particularly gloopy oil to lube the manderal (done by some one else, we have zero control there customer supplied). Hence degreasing it is probably not going to happen in something water based even at temperature. A solvent tank large enough with surficant capacity just is not a option - too costly to fill and dispose off for our limited use. A solvent tank sized just for the brackets would be manageable though. That said im pretty certain they could be cleaned using a detergent of some kind, there really not badly oily!
As to a oven i already have a lead on a little bench top model. Can easily hang 30+ brackets a time and with a couple of racks could swap and get some good production going. Once proven making a bigger oven and going after the other parts or just adding a second little oven for the brackets is not a issue. Anyone looking to make a oven may want to look into fan oven elements and the matching fans to go with them. There darn cheep and a very scalable option. Its definitely the way i would be going for a larger oven if i was to make one. Professional powder coating ovens seam to be ridiculously over priced to say the least!
As to powder being messy i have a fair idea my other lines of work often involve contact with toner from industrial sized digital laser printers. I am assuming powder coating is going to be on a similar level!
Has anyone any experience with fluidised bed coating? Seams a viable alternative to electrostatic spray for parts like this?
I disagree. 1000 parts per month is easily doable in a home shop AND the quality will be just fine. I use a recycled stainless steel isolation booth (like a sandblast booth) to contain any powder mess. From your response, it is clearly obvious that you have not sprayed any powder. It is easy, simple, and affordable for small items. In my small shop I use a Sears gun (no longer sold by Sears but picked up by these guys):
Originally Posted by Ries
Powder Coating System
Several years ago I did an evaluation of the Sears system:
Riser's Powder Coating Trials
A high school kid can be given the task of powder coating 1000 parts and be paid by the completed piece. You would be amazed at how fast 1000 small parts can be done in a home shop - and the kid earns more than he could flipping burgers. This is a simple and doable job for a small even home shop.
It's interesting you should write that Bob, as I have a one off job I'm currently doing where the parts are long and thin, hence won't fit in my oven. I was thinking about sending them out to be done, and will still get a quote to do so, however I'm also considering building a temporary oven from wood for the job, doing the few cycles, and dismantling it after. I think some commercial powder coaters like to perpetuate the myth that there's something extraordinary about this whole process, and it certainly appears to have convinced a few customers anyway! :; There's no doubt some parts can be a little tricky to get perfect, but simple brackets like these are about as easy as powder coating gets. It's no space shuttle launch either, despite what some may have been convinced of!
Originally Posted by Robert Campbell Jr.
Adama, being one of the Rube Goldberg types, my imagination runs wild.
I "devined" a parts rack, suspended from the outboard tip of the horizontal member of an "L" shaped arm. Small open-front spray booth with vacuum and filters, (disposable house-hold HVAC filters?) on wheels rolled around the rack, it given a little twist to spin in front of the spray gun.
Coating completed, the booth rolled back, suspending "L" turned 180° and from the other side, the oven rolled over the rack, suspended parts undisturbed. Rack lowered 'til legs rest on oven floor, "L" arm extracted and oven door sealed. Set timer. The "L" arm could be on a light jib crane, spray booth and oven stationary?
Now maybe a third station with a light pressure washer and a surround with window, like an abrasive blasting cabinet? Bio-degradable detergent in hot water followed by hot clear water. The lid with parts suspended below on the rack, lifts from cabinet and the hot clean parts air dry rapidly, on their way to the other 2 stations.
Here in the desert, I have a wide shallow pan in which I drain used bio-degradable detergent water and scrape up the minor amount of dried residue for disposal. The surfactants penetrate the oil, making it biodegradable as well. Where you are, even with a transparent plastic roof over, it might not evaporate quickly enough for production. Hmmmm, no insulation on oven top, which is the evaporation pan....they're coming to take me away....
Pete, I doubt that John spent a whole day constructing his oven, scrap wood and purchased insulation. The old kitchen range a givaway. His is up about 2' from the ground, top of oven above head height, perfect access. I'd probably use that concrete based tile backer board inside for wear factor. Wood ignites at about 450°F, so heroic measures to insulate it from the heat aren't needed, just a little isolation. For intermitant use, I would feel safe screwing the heavier 1/2" thick, mesh and concrete type backer board* directly to the wood frame.
*available to me locally in 2' X 4' sheets, big box strores.
For a permanent oven, steel tube, board insulation and the 1/4", harder backer board as durable lining, it too is available in 2' X 4'.
It might be encouraging to run an oven cubic foot per dollar comparison between the big guy fat-cats offerings and the parts for DIY. The argument, "they gotta' earn a living too", prompts me to answer, "but not off of me". I get by without corporate jets and am not inclined to help buy theirs. All I've got to do, is earn my own living and like Poor Richard said, "a penny saved is a penny earned".