Induction heating for case annealing?

[popper]

The coil is copper. Brass & copper are not magnetic so the coil & brass temps will be the same. Coil needs to be cooled. Ferrous metals induction heat very easily, brass not so easy.

[Mr_Sheesh]

I've seen quite a few inductive heating coils made of copper tubing, water flowing through it will cool it nicely. They used to use a 555 timer IC but (IMO) the microcontroller such as an Arduino (Uno or even the Mini's that are only $2-$3) is a far superior answer - You get reliable and far more accurate control. On the other hand you could make a flame type annealing setup with a valve that would shut off the gas, should the unit fall over, or just make it so it is unlikely TO fall over (bolted or clamped to something solid, for example.)

[Yooper003]

With that big plastic base for 16 oz. propane that comes with Coleman lanterns, it is very hard to tip over. Sill like propane torch with socket that cas will fit in & electric drill

[Blitzfike]

For those intersted in cheap chinese stuff her is a link. I have played with three or four different models they offer and the power supply is the critical element. You need your power supply on and working before you power up the induction unit. I've let the smoke out of a couple of them so far. https://www.banggood.com/search/induction-heater.html Edit to add that I use a TIG water cooler forf the big unit's coil. Keeps it cool as can be. One of the smaller units uses a fountain pump for cooling water.

[Mr_Sheesh]

You can sometimes find better deals at aliexpress; Sadly some electronics parts aren't made in the US any more.

[JeepHammer]

Some things you should probably know...

Tempilaq (thermocromatic paint) isn't accurate.
It uses both copper & zinc in it's makeup and the cartridge brass screws with it, I got this directly from a Tempilaq tech.
If you want to prove it to yourself, paint one side of a case with 750*F and the other side with 800*F and heat.
The 800*F will change color first every time.

There are two ways to control the energy delivered to the case,
Either you leave the coil on full time and control the TIME the case is in the coil,
Or you control how long the unit runs, switch it 'On/Off'

Most of the surplus/discount units are for 'Solder Pot' applications or heat sealing.
They come with tubing for cooling, and these units normally don't live long when you cycle (switch them On/Off)

Some come with solid core wire, or flexible wire & Ferrite core.
These are usually built to switch On/Off (cycle) since they don't have provision for cooling.

You will find the tubing & solid wire versions are VERY hard to keep the annealing in just the neck/shoulder area, it's a wide open coil, the magnetic field is hard to control.

The stranded/flexible wire (usually Litz wire) and a slotted Ferrite core will focus the magnetic field between ends of the Ferrite MUCH better and concentrate the power of weaker units.

AMP, Fluxeon 'Annie', etc use a Ferrite, and use digital timers for cycling.

The 'Annie' will take the case shoulder/neck completely off a .223 or .308 case in just a few seconds.
.223 slag is about 8 seconds, while .308 is closer to 12 seconds.

Keep in mind I had to 'Detune' my Annie, it didn't allow enough saturation time for the annealing process to happen.
I didn't own the AMP long enough to get that far, it has 'Programs' instead of direct read time, and the power supply isn't tuneable, it's full power 100% of the time it's on...
The ONLY adjustment you get is time.
'Annie' has the better timer simply because it's direct adjustment/read. (And it's about 1/4 to 1/3 the cost of AMP)

This is a surplus 'China' unit, does OK as continuous 'On' but doesn't like being cycled. I've killed a dozen of them, but at $30-$40 each they are cheap enough to experiment with.

[IMG][/IMG]

I STRONGLY suggest some fiberglass wrap for coils no matter what you wind up with.
Pretty easy to get a case against bare conductor and short the unit out.

[IMG][/IMG]

You WILL want a fan for the heat sinks on the annealing unit, good idea to get it in the voltage your power supply is putting out.
You WILL need a power supply that can keep up, anything under about 1,500 watts at rated voltage won't give you full output from the unit. (Don't get those stupid little LED light power sources).
Digital times are $5 all day long, that's no issue, just make sure it's in the voltage range of your power source.

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This is a link to 'Annie',
The Ferrite shown on the front of the machine isn't my favorite, but it's one size fits all...
https://fluxeon.com

This is a Ferrite with Litz wire, these come in a couple different gap sizes to better suit the case.
https://fluxeon.com/product/giraud-retrofit-coil/

It's a bit steep since Ferrite rings are between $2-$5 bucks on the surplus market and a $20 roll of Litz wire will last you a lifetime for this stuff...
Dirt simple if you want to experiment!

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Now that I know about annealing, I've not seen one single person do flame annealing correctly, that includes me.

If you see a (reputable) manufacturer flame anneal, you will see a long row of defused flames, cases moving (relatively) slowly past those defused flames.
This is lower temps, and longer duration.

I'm like everyone else, I used the oxygen engorged 'Jet' tip on the plumbers torch and WAY overheated the outside of the case. This leads to delamination of the brass grain structure.
I don't flame anneal at all, opting for open coil (defused) electro-magnetic annealing, or when I want it really precise, 'Hot Pot' annealing.

The cheapest way to accurately anneal is a lead smelting pot (Hot Pot) and glass, ceramic or steel shot blasting beads.
Small enough to easily get into the necks (and back out), and enough thermal mass you can do several cases at one time without lower the temprature of the pot.

You get accurate readings with a thermometer instead of thermocromatic paint, and the entire rig comes in under $100.

You will need a 'Paddle' with holes drilled in it for cases, metal or wood is fine...
Saves on burned knuckles (ask me how I know that...)

Some guys opt for salt, but I have an issue with a volatile corrosive liquid heated to the point it will melt skin, I screw up enough without adding to the danger level.

I opt for stainless steel shot, good thermal transfer, and no moisture issues.

With temp in the 730*F to 750*F range, it's just about a minute and you are done, nearly perfect anneal every time. If I were doing smaller volume, that would be all I'd do.

For electrical annealing, here is a video of cases being shoulder/neck annealed properly, notice the time factor in the coil, notice they never 'Glow', and notice the open coil they are going through...

https://m.youtube.com/watch?v=Ira3dm...hBN5Al&index=8

[vagrantviking]

I never cared for the molten salts idea either. Tried annealing in lead but the soldering issue of lead sticking to the cases was a pain.

Been getting pretty good success with the drill and torch but still difficult to get the level of control I would like.

Steel shot in a leadpot is a genius level of simplicity. Definitely going to try that.

Could you please explain the paddle you mentioned. Kinda hate cooking my fingers too.

[jpndave]

Nice writeup JeepHammer I'm going to look into those options. What size SS shot are you using?

[Grmps]

Great write up. would you please post links to:
This is a surplus 'China' unit, all the parts needed and a description on how to build this. Most of us don't have your depth of understanding in these matters
Ferrite rings
$20 roll of Litz wire
glass shot blasting beads.(please include preferred size)
ceramic shot blasting beads.(please include preferred size)
steel shot blasting beads.(please include preferred size)
Which of the blasting beads do you find works best

[country gent]

I use very fine glass making sand in a lyman lead pot. This is very fine sand and flows well. I have a rack made up that sits in the pot and sand under and around it. The rack holds 12 cases in the ring. this gives about a 15 sec soak time. I use a lead thermometer to set temp and a 40-50 min warm up time this allows the sand to fully heat and to get the 750* temp thru out the pot. I find the sand works better than steel shot since there are fewer air gaps in the media.