Best Method to Strip enamel off magnet wire

[steveb]

I'm curious what methods people use to strip the enamel off magnet wire without damaging the wire.

I've heard that chemicals can be use, but never tried this, and now don't even remember what chemicals would work, or whether they are safe.

I usually just scrap the enamel off with an exacto knife, but I've never been happy with this method, since the wire is always damaged to some extend. I get by with this, but I feel there must be a sure fire method that doesn't involve chemicals that will send me into renal failure.

Any suggestions are welcome. Even if you don't have the perfect method, I'd be curious of the various techniques that are employed, and whether you are happy with the results of your method.

[beenthere]

You can always use acetone, but the fumes are pretty bad.

If the wire is big enough, scraping with an Xacto blade works pretty well. I almost always scrape it off. An alternative is to stick the wire end into a small flame and burn the enamel off.

[jpanhalt]

I have tried acetone and some other solvents, including chlorinated solvents, acetonitrile, DMSO, DMF, and HMPA. They do not work with modern wire. The following comments apply to magnet wire with non-solderable insulation. If you have a solderable version, just use your soldering iron.

One method that does work and is sold commercially is a molten salt bath called Dip Strip by Eraser (http://www.eraser.com/catalog.cgi?mo...roduct_id=1442). Mechanical devices (imagine something with counter rotating abrasive wheels) and just heat also work. Eraser sells a variety of devices for removing enamel insulation.

Dip Strip uses a proprietary mixture of NaCl, NaOH, and NaNO3. It melts at 260°C and works at 370 to 400°C.

Earlier this year, I experimented with my own chemical stripper. Pure KOH or NaOH will work, but are relatively slow. I found pure NaOH to work at 325 to 335 °C. Adding NaNO3 speeded up the reaction considerably.

The enamel insulation is removed cleanly, but upon removal from the salt bath, the copper darkens (tarnishes) quickly. So, you may still end up cleaning to get a good solder joint. Darkening was affected by different ratios of salts. I used a ratio of 1:4 to 1:6 (wt/wt)for NaNO3 to KOH or NaOH at about 305°C. That is probably not optimal, but it works. I did not look into adding NaCl to find its effect on the darkening. The nitrate salt is apparently consumed in the process, particularly at higher temperatures.

The apparatus I used was made from a scrap block of steel 2.25" square and 1.25" high. I drilled a 5/8" diameter hole for the salt bath and a smaller hole for my thermocouple. About 4.5 g of salt mixture filled the well when molten. The block was heated by placing it directly on the electric burner of my stove.



The biggest disadvantage is radiated heat from the block. Crumpled aluminum foil worked fine to block most of it. The block retains heat for quite awhile, so it can be removed to a cool burner during the time that you are stripping wire. The other disadvantage was getting a wound coil close enough to the bath to immerse the short ends. It is best to remove the insulation when there are a few inches still left to be wound. Once the coil is completely wound, I just use abrasive.

I have thought about using Cratex (rubberized abrasive) points in a Dremel or handheld. I think that would work. I have just been too lazy to try it.

John

[Ron H]

You can buy magnet wire with solder-strippable insulation. There appear to be several brands available.

[hgmjr]

Originally Posted by beenthere

You can always use acetone, but the fumes are pretty bad.

If the wire is big enough, scraping with an Xacto blade works pretty well. I almost always scrape it off. An alternative is to stick the wire end into a small flame and burn the enamel off.

In addition to the techniques mentioned by beenthere, I have found fine grit wet/dry sand paper to be an effective stripper.

hgmjr

[Duane P Wetick]

We did the HAPTZ & Formvar stripping on a daily basis, and made special tools to do the job; nippers w/ moon face cutting surfaces. This required skilled operators, but the technique was picked up quickly.

Regards, DPW

[Bernard]

I still use a match or lighter & verry fine abrasive nail file; used it yesterday on some .oo9 wire.

[SgtWookie]

A disposable butane lighter and a 3m Scotchbrite pad work quite well.

With some of the magnet wire that's available (like Ron_H mentioned; I think it's polyamide insulation) a plain old solder pot works really well; just dip the end into the molten solder for several seconds, and you get a nicely tinned end.

I made a solder pot out of a salvaged coffee urn heater and a 24v 4A transformer. Takes 15 minutes or so to warm up, but works well.

[Ron H]

Originally Posted by SgtWookie

A disposable butane lighter and a 3m Scotchbrite pad work quite well.

With some of the magnet wire that's available (like Ron_H mentioned; I think it's polyamide insulation) a plain old solder pot works really well; just dip the end into the molten solder for several seconds, and you get a nicely tinned end.

I made a solder pot out of a salvaged coffee urn heater and a 24v 4A transformer. Takes 15 minutes or so to warm up, but works well.

If you are just doing a small job, and you don't have a solder pot, a blob of molten solder on the tip of your iron will remove solder-strippable insulation in a few seconds.

[steveb]

Thanks for the great information everyone!