First off, we always say melt the "enamel" off, but thats just a phrase, since real enamel mag wire has not been used for years, unless some botique winder is using old stock wire to get the same capacitance properties in order to duplicate an S 217 D or something.
But "enamel" is easier to spell than poly-chromybrimuidehsjhcopehriuyher, so we use it in place of just about every type of mag wire insulation there is. There are currently about ten different types used, depending on heat/breakdown catagory.
There is more than one way to skin a cat.
Tinning depends on the gauge.
From small to large:
It is hard to tin #44 to #58 without risking meltdown. So you wrap it around a bigger conductor, like a pre tinned piece of regular pvc 22 gauge, starting from the insulation side of the tinned lead and working your way out, then, you "hit and git" with the soldering iron, starting a small puddle of solder on the end of the pvc lead, and bleeding it toward the thin wire, until it just makes contack. The resisdule heat will carry the pudlle onto the thine wire, melting the enamel (for lack of a better word) insulation.
For #26 to #43 - there are two possiible types of wire you might encounter - solderable and unsolderable. Lately, especially in power transformrs, where heat is the main issue, haevy, triple build poly or even extravagant insulation types have sometimes been employed, much to the chargrin of the DIY er. Gone are the days when all you had was red enamel, an insulation you knew your iron would melt like soft butter.
The worst offender in the unsolderable catagory is Kapton.
If you happen to be unlucky enough to come across some of this wire, which is unlikely, since it is super expensive and only used on the shuttle, you might need a blow torch to get thru to the copper. They even sell a quad dipped Kapton magnet wire, Doc Hoyer uses it ion his high voltage Mac outputs, he did a Jakobs Ladder test on twp paralell pieces of wire in his basement with a Neon transformer. He said there was zero corona at 50 KV, with minimal seperation distance. That's good if you are the customer, but bad if you are a winder. In this case, you might need a super expensive mechanical spiral type wire stripper. This device has what look like three damaged helicopter blades on the end of a small hand held motor, almost exactly like a dremel motor. As you increase the speed, a cam uses the centifugal force to pull the rotating blades against the wire, thus stripping off the insulation, but not the copper. You have to adjust the RPM per the gauge you are using. If you spin it too fast, you will cut right thru the wire. Two slow, and you leave a resisdual layer of insulation that makes soldering difficult.
If your lucky, you have some old school third world enamel, although even China is using high temp wire nowdays. We had a terible problem with this at work, due to a commu=nication (umm, engneering) problem.
OT; This is a true story that happened at work not long ago.
China. We ordered 5000 torroids from them. They were supposed top be 2000 turns, but the eng dept specified henries, not turns! So the Chinese were winding thre 2000 turn coils, then unwinding them, the amount of turns being unwound being determned by how many henries the now tweaked coil has. Not low enough? Take off some more turns. This was causing us grief, becuase we calibrate by turns, not by Henries!
So we were installing different burden resistors to make up for the small descrepencies of the coils, trying to match everything to a 0.5 percent tolerance! So both parties were working against each other, needlessly. S SOON AS GOOD OL CJ SOLVED THE PROBLEM, OUR TWEAKING HASSLES WERE OVER.
bUT MY POINT HERE IS THAT CAN YOU IMAGINE THE LABOR FORCE THEY HAVE OVER THERE, WHERE THEY CAN TWEAK 5000 TORROIDS, TURN BY TURN, IN A MATTER OF DAYS, JUST TO GET OUR COIL "IN SPEC" ? aMAZING. tHAT WOULD HAVE TAKEN A YEAR AT OUR SHOP!
(the funny part about this is I ended up being the hero (the mgr went to the CEO and told them what a Genius I was) for telling them about something I learned on the net at work, when I should have been troubleshooting circuits!)
aNYWAY, TIRED OF TYPING, SO JUST USE AN EXACTOR BLADE TO GET MOST OF IT OFF, THEN SOLDER IT TIL YOU SEE TOXIC SMELLING FUMES, THIS IS THE INSULATION BEING VAPORIZED. qUIT AFTRE THE VAPORS TAPER OFF TO NEXT TO NOTHING. gO ANY FURTHER, AND YOU
are degerating the copper alloy.
For the real heavy stuff, like #4 rect (rectangular magnet wire for the big power transformers) you use an oxy acetelane torch, believe it or not. A small flame of course, not cutting torch attachments on the end of the winder's hoses.
Brazing with silver solder or a special brazing rod alloy is used for hooking up 90 degree buss bar terminals, etc, to the pwr trans primariy.
It takes a long time to heat up a 1/2 ich by 4 inch copper buss bar primary. Ypou are essentilally pooring heat into the whole winding, until you get the coil hot enough so that the part you want to braze is hot enough aslo.
Sometimes the winders would have to use wet towels to cool the work right after they solder it, so the heat did not travel down and damage something inside the coil. On those monsters, we used #30 Nomex, (0.030 ich thick) as interkayer insl.
You could hlod the hottest part of the torch on that stuff for a minute before it would burn thru. Absolutely amazing stuff, that arimid fiber.
I remember big steam clouds every so often, then we knew we had to bake out the coil, to get all the water out of it, otherwiswe, one drop of water in a 400 gallon oil tank, and you have a hi pot failure, which means un tanking an oil filled transformer, und taking it apart, layer by layer, so we could deduct a raise from the winder next quarter.
Imagine taking apart a PCB soaked transformer. Ugh! Good thing that nasty stuff was going out while I was coming in.
The better the wire conducts current, the better it comducts heat also.
Ever notice that it takes more heat to solder a 10 ohm resistor than a 1 meg?
took me a while to pick up on that one.
So soldering, brazing, welding, it's all about heat control.
You can sometimes make life easier by splicing on a smaller wire to the xfmr lead, , then solder that wire to the board. Use one layer pvc tape, then shrink wrap over the splice.
