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Old Aug 10, 2012, 01:43 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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"..I've seen fiber laminations used just on each end of the stack for insulation. They are sometimes slightly oversized to be sure to cover the edges of the laminations..."

Anyone that is seriously interested in insulating stators can go to the powercroco and powerditto pages and see some of the masters at work. With or without the translations by google, it is wonderful stuff to look at. A couple of examples, the first two using some kind of paper or thin sheet fibreglass on a bare, uncoated, stator:

12N10P4035 Scorpion V1 - http://www.scorpion.powercroco.de/12...corpionG2.html
German to English translation - http://tinyurl.com/d36sokb

12N10P4030 Speedscorpion - http://www.scorpion.powercroco.de/12...dscorpion.html
German to English translation - http://tinyurl.com/c2uwc3e

This one shows how to make the fibreglas end caps they use on the ends of some of the larger bare stators:

Isolating a stator pack - http://www.powerditto.de/statorisolieren.html
German to English translation - http://tinyurl.com/9pl927w

I don't speak or read German, the google translations border on unintelligible at times, as always the pictures are worth many, many words.

Here the starting pages for all of that:

http://www.powercroco.de/

http://www.powerditto.de/index.html

If anyone can decipher the brand names and North American sources for some of the exotic insulating materials in use there (papers, sheet fibreglas, etc.) it would be wonderful. I will personally designate that person a Hero of Motor Rewinding and do all I can to make it a sticky thread!

Jack
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Old Aug 10, 2012, 10:26 PM
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I'm having good success with Kapton tape strategically placed and multilayer-ed in some spots. I just finished taping a 2215 12n stator the job took about four hours. The first set of wires I removed from the stator the OEM goop held up and I rewound it in about an 1.5hrs with 23AWG. One of two mistakes I made with this motor, is I used CA to bond the stator to the bearing tube, I was out of red Loctite. So I used debonder to loosen the CA and it attacked the coating. I don't mind the job to some degree, but it's like when I built my first boat. When I told someone what I put into it they would say it should've been 10' longer. My quest for a better solution to this problem is allow me more time to wind one time. There's allot of broken motors to fix ya know. If I were building top notch monster motors I would feel more justified spending so much time on one step.
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Old Aug 20, 2012, 12:53 AM
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United States, IN, Indianapolis
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Just came across this thread. Just wanted to chime in a bit on the stator coating with powder process.

I work for a motor manufacturer and we make LARGE, axial flux brushless motors for electric vehicles and military applications.

We occasionally use a powder coating for our stators. The powders do not need to be electrostatically applied. The stator can be heated to the flow temp of the powder and the stator simply dipped in the powder. This generally results in a slightly higher build thickness than you would get applying electrostatically, but with some experimentation could be a viable method for smaller stators.

The powders can also be "flocked" on. Put the powder in a salt shaker, or a real flock dispenser from the hobby shop, heat up the stator to flow temp and shake it on. A re-flow may be needed to even out the coating.

The can also be applied to a hot stator using normal "air" paint guns as long as the air is COMPLETELY dry.

The stator MUST be PRE-HEATED in order to use non-electrostatic methods. the benefit of electrostatically applying the powder is it can be applied to a COLD part.

There are also a few companies that sell electrical coating powders in small quantities. We have a few different "quart size" containers we bought. I will find out where they are from.

Also, normal powder paints should be adequate for insulating stators as long as they are non-metallic. I have worked with both, and as far as I can tell, the "electrical" powders we use, and normal powder paints have no real difference. Especially since all we are really using it for in this application is to prevent mechanical wear on the wire enamel during winding, and vibration when operating. The build thickness is essentially the same on both types.

Harbor Freight sells powder in 16oz containers for $5 of a few different colors that are cheap enough to experiment with.

There are also high-temp, high-build spray epoxies, and lacquers we use for the same process.


@jackerbes -- The most widely use electrical insulating "paper" is Nomex. Its actually the same material used for most of the "CA" hinges used in most planes these days. Find it HERE You can get it adhesive backed as well, which makes it easy!!

Also, Park Electrochemical makes the fiberglass sheet you are looking for, sold under the Nelco brand. You can get it at least down to .006" thick for sure, maybe thinner. Its not expensive and is available in smaller quantities. We used to use the .006 for insulating the bottom of our stator teeth. It can be cut with a pair of scissors and a hobby knife.

Also, I seen the thread on removing epoxy from winding to get them off. The epoxy generally used for this coating is usually Epoxylite, or the Chinese equivalent. It is known as a "Trickle Resin" . It is a very thin air cured resin generally used to simply hold windings or laminations together. Its very thin to provide penetration. Dolphs sells some of these resins in a spray can, as well as some other insulating materials.


EDIT: Look what I found HERE Nelco .006 fiberglass sheet in 12x18 sheet for $2
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Old Aug 20, 2012, 08:16 AM
Jack
USA, ME, Ellsworth
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Wow! Thanks for the details and links/ You are a gold mine of information on stator coatings and insulation.

Just one quick question, about how hot do you have to get the metal parts to get the powder to stick when you dust it on?

And how much heat does it take to get the powder to turn into a liquid for dipping?

I really like the idea of dipping a stator into a shallow pan of melted powder so that tops and corners of the arms are immersed and become protected.

Jack
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Old Aug 20, 2012, 08:53 AM
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Yes the corners are the cutting edges.

WEST system epoxy I used is relatively low viscosity resin - thinner than glue. It is slow to cure also, so not ideal. I actually waited until it thickened a little before dipping because I didn't want the corners to drain off over the long cure period while it was hanging.

Fast hardening and lower viscosity would be better. Then the corners and flats would be more uniform in coating thickness. That means both more room for windings and more resin on corners.

The Harbor Freight powder and non-electrostatic methods sound really do-able and within reach for DIYers. Thanks for the great info!

(Have to admit, though, if I can avoid using thinners to remove windings in future by using heat (and the Harbor Freight plastic welder) I will.)
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Old Aug 20, 2012, 01:52 PM
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http://www.harborfreight.com/plastic...ure-96464.html
A link to the air welder, I gather from reading reviews that the model without the fan is preferable because the airflow is non adjustable,The start and stop instructions have to be followed other wise it breaks quickly . Most likely this tool could be used to apply the powder coat.
Thank you for all the great info KKUSA
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Old Aug 20, 2012, 04:42 PM
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Quote:
Originally Posted by jackerbes View Post
Wow! Thanks for the details and links/ You are a gold mine of information on stator coatings and insulation.

Just one quick question, about how hot do you have to get the metal parts to get the powder to stick when you dust it on?

And how much heat does it take to get the powder to turn into a liquid for dipping?

I really like the idea of dipping a stator into a shallow pan of melted powder so that tops and corners of the arms are immersed and become protected.

Jack
You dont have to melt the powder first, just dip a hot stator directly into the dry powder.

As far as temperature, it varies depending on the powder, mainly due to particle size, and what sort of finish you want. Usually we heat to about 200c , which is well below the annealing temp of the stator material, and allows for a nice even flow.

You can heat the parts in your home oven , if the wife permits!!! Or for small parts like R/C stators, a toaster oven would be ideal.

If you look HERE, you will see the green stator in the housing on one of our machines. This was done with the above "hot dip in dry powder" method.
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Old Aug 20, 2012, 05:13 PM
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I also wouldn't use the plastic welder to try to melt a powder coating. The airflow would likely blow the powder off! An oven or hot stator sounds much better.

I don't have experience with the two listed HF welders. Mine is an older model that came with a low pressure adjustable regulator. That and a router speed controller allows control of both airflow and temperature.

If I were to buy one now, I'd by the less expensive one (no fan) and add a low pressure regulator.
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Old Aug 20, 2012, 11:48 PM
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Originally Posted by vtdiy View Post
I also wouldn't use the plastic welder to try to melt a powder coating. The airflow would likely blow the powder off! An oven or hot stator sounds much better.

I don't have experience with the two listed HF welders. Mine is an older model that came with a low pressure adjustable regulator. That and a router speed controller allows control of both airflow and temperature.

If I were to buy one now, I'd by the less expensive one (no fan) and add a low pressure regulator.

Yea, dont use anything that "blows" to flow the powder, it WILL blow away.
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Old Aug 21, 2012, 02:59 AM
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Long ago, I worked in a GE plant that made relays, transformers, and a few motors.
One of the processes used was with a very thin epoxy.
You pulled a vacuum on the epoxy as a preliminary step, then placed it and the stator in a vacuum chamber. After pulling down the chamber, the stator was placed in the epoxy (actually several at once), and the vacuum increased, then released. The stators were removed from the vacuum chamber, and the epoxy cured in an oven.
After I quit, and went to work in the defense industry (1970s), more and more of the plants products were transferred overseas.
Eventually, the motor production was moved to Mexico, and totally different designs were used. (less expensive, less durable, etc)
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Old Aug 21, 2012, 04:32 AM
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http://www.harborfreight.com/catalog...?q=powder+coat
When my local HF opens a little later this AM I'll check to see if they have this stuff in stock. I just happen to have a naked stator needing a coat. My comment on the plastic welder as a preheat source then apply powder or perhaps a way to blend in a small repair. I'll get the stuff and find out. I have other uses as well for the plastic welder. I see they don't have green PC. I think a yellow stator would look nice although I'm partial to red. Any thing but green or as they say, green is red.
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Old Aug 21, 2012, 08:24 AM
Jack
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So when you spray the powder onto the bare hot stator, it flows and forms the finished coating? Is that the drill?

Jack
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Old Aug 21, 2012, 08:43 AM
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Yes, see post #14. Spray or sprinkle as in post #18
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Old Aug 21, 2012, 09:00 AM
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You'd want to mask areas that don't get coated. I used wax for the epoxy coating but that was a cold coating. Easy to remove, easy to see when putting on, and doesn't mix with the coating.

KKUSA what do you mask the bearing tube/stator ends with for a hot process, like powder coat?
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Old Aug 21, 2012, 09:59 PM
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Quote:
Originally Posted by vtdiy View Post
You'd want to mask areas that don't get coated. I used wax for the epoxy coating but that was a cold coating. Easy to remove, easy to see when putting on, and doesn't mix with the coating.

KKUSA what do you mask the bearing tube/stator ends with for a hot process, like powder coat?
Kapton tape!!!! Just peel it away before it cools completely. It can take quite a bit of heat.

If you are sprinkling the powder on, do it fast so as not to let the stator cool too much.



Jackerbes, I guess it would be possible, once you have flowed the powder to use a heat gun or the plastic welder to reflow imperfections etc. I would do it before the stator cools from initial coating though, as once its cool it takes more heat to reflow, and may actually burn.
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