Induction hardening of cutting edges.

[oldbikedavey]

Pondering over how best to wangle the deed on a 240 V supply, and a moderate quantity of cunning.....

 

[hotponyshoes]

What sort of edges?
A chisel tip will fit in a small round coil and you can run from a 13a plug.

If you want to heat soak a 10" chef knife you'll be hard-wiring into an 80a supply.

If you can get 3-phase things would be easier..

 

[dieselsamurai]

well theres these i guess

Draper 99798 Car/Van Vehicle Induction Heating Coil Gun Tool Kit 230V

Easy to use induction heater, operated by simply installing the appropriate coil type and placing over or around the ferrous metal for heating. Induction…

www.primetools.co.uk

or

https://www.amazon.co.uk/Voltage-Induction-Heater-Heating-Flyback/dp/B0C3D34F3R

 

[Kram]

Why induction when you have the 75kW burner?

If you want to heat soak a 10" chef knife you'll be hard-wiring into an 80a supply.

Quite sure my 3kw cheapy will get a chef knife to red hot.

The issue is the curie point, you need to heat past that. Basic induction setups wont give much headroom for quenching due to the large drop of conversion at curie.

An option is to coat the blade in graphite, which does heat past that point, but its messy stuff.


Another option is save the money for argon gas and tig weld some HSS onto your edges. Ofcourse depends what they are for.. my welded HSS tools have done very well, no need to sharpen them yet.

 

[Agroshield]

What area of hardening do you wish to achieve? I may be misunderstanding the thread title, but the picture in my mind when reading it is how the teeth of a hardpoint saw are hardened - very local to themselves and not the whole piece of steel that makes the saw.

That is what I understand the benefits of induction hardening to be. You see 'induction hardened' on lathe beds. They sure do not heat up the whole bed casting to do that but apply heat very locally to the ways and have a big stream of water following the heater.

 

[hotponyshoes]

Quite sure my 3kw cheapy will get a chef knife to red hot.

You can get it hot but controlling it is the problem.
I'll put up some photos of my setup later.

If you just want to harden the cutting edge (which I think is what the op is after?) you'll need to use blocks or an oval shaped coil. Both need a disproportionate amount of power.
Then, if you want to add pulse, ramping, soak timing, etc you'll struggle to find a machine with those capabilities that won't trip a 40a breaker when you turn it on*

*it's been a couple of years since I got mine, at that time 3ph versions would run from a 16a supply but not 1ph. They might be available now?

 

[hotponyshoes]

What area of hardening do you wish to achieve? I may be misunderstanding the thread title, but the picture in my mind when reading it is how the teeth of a hardpoint saw are hardened - very local to themselves and not the whole piece of steel that makes the saw.

That is what I understand the benefits of induction hardening to be. You see 'induction hardened' on lathe beds. They sure do not heat up the whole bed casting to do that but apply heat very locally to the ways and have a big stream of water following the heater.

You can do knives this way, drop the blade down through a coil into the quench.
The thinner sharp edge will heat quicker than the spine but not quick enough for a heat-soak.
Works fine for production but a lot of trial and error setting up so hard work for one-off jobs

 

[Kram]

I suspect the edges in question, may be those from a garden shredder, to be used for a quite unrelated purpose.

 

[oldbikedavey]

I suspect the edges in question, may be those from a garden shredder, to be used for a quite unrelated purpose.

Not so...
It's for pinking blades in a paper bag making machine.....

 

[hotponyshoes]

Not so...
It's for pinking blades in a paper bag making machine.....

Presumably round blades?
They would go easily enough without needing much power as you can make the coil the right size and hold the blade above/under rather than putting it inside

 

[oldbikedavey]

Presumably round blades?
They would go easily enough without needing much power as you can make the coil the right size and hold the blade above/under rather than putting it inside

Think that they are flat, but will check.
I keep trying to get that particular mate to join this forum, as he would have much to learn , and a much greater amount to contribute.....
But , this is East London, and Stubborns R Us....
Unless someone else is paying, of course....