Case Hardening

[DalboyParticipant @dalboy]

I notice that some parts on the Rob Roy need case hardening, I have found some powder in various sizes/weights.

Can anyone give me an idea how much it would need to case harden a piece about 2" x 1" X 3/8" not solid, this is to just give an idea how much I will need to order they start from 100g upwards to 1kg from what I have found.

If I brought too much how well does it keep or is it something that will keep for a lifetime, what I don't want to do is not order enough at the same time not order way over the top.

I should imagine for smaller parts than what I described above I could do multiple items at the same time.

This is what I have found from HERE as well as other suppliers, where has anyone brought some from in the past and is that brand any good for home hardening

[DalboyParticipant @dalboy]

[BazParticipant @baz89810]

I will start off by saying that it keeps for years, mine is 35 years old and still working fine. I used to do a lot of case hardening back then and bought the stuff in I think 10 kilo tins, For Rob Roy bits a tobacco tin full will do, heat the part up until dull red and dip it into the powder, if powder doesn’t stick it’s not hot enough, heat the component for about five minutes, dipping into powder as necessary and then quench in cold water and jobs done, when all the crud is removed you should have a matt grey surface left which hopefully will be glass hard. The longer the job is heated the deeper the case, if you can put it in a furnace that would be ideal but dip and heat method works well, just depends how long you want to stand there twiddling bits around in the flame, don’t do too much of it indoors as the fumes aren’t particularly good for you.

[Clive HartlandParticipant @clivehartland94829]

The part to case harden will only get a very thin hard zone. The way to do it is to heat to a red heat and dip into the compound and then back into the flame. A dip in salty water will lso remove most of the compound.

Need it harder and deeper, repeat the process. The question of how much you need is a container that it comes in!

A more rigourus method for even depth is to put the item in a metal box filled with the compound, sealing if possible. Cook in a flame for a while at above red heat, maybe 15 to 20 minutes, a full quench in cold water will give the best result.

The one I use is Kasenit, it is available and comes in 3 or 4 size tins. Varying in price from £9 to £20.

Edited By Clive Hartland on 06/02/2022 15:18:58

[roy entwistleParticipant @royentwistle24699]

Clive. I understood that Kasenit is no longer available. I think Blackgates do one

Roy

[BazParticipant @baz89810]

Kasenit has not been available for years, the modern stuff works equally as well and doesn’t seem to give off such overpowering fumes. I think that wherever you buy from nowadays you are getting the same thing. There used to be two versions of Kasenit, numbers one and two, I don’t know what the difference was, I always used number two, I am sure someone will enlighten me before the day is out.

[DalboyParticipant @dalboy]

Thank you everyone looks like I will buy one a little larger than needed at least I now know it will last

[DMBParticipant @dmb]

Ground up bone used to be used – bonemeal from garden centre?? Could be cheaper. I have also seen a recommendation for sugar as that is mainly carbon and it is the carbon that's needed. Don't understand why someone recommended that as it's flammable!

[Clive HartlandParticipant @clivehartland94829]

Knighton tools.co.uk seem to have kasenit.

[vic neweyParticipant @vicnewey60017]

Posted by DMB on 06/02/2022 22:05:23:

Ground up bone used to be used – bonemeal from garden centre?? Could be cheaper. I have also seen a recommendation for sugar as that is mainly carbon and it is the carbon that's needed. Don't understand why someone recommended that as it's flammable!

—————————————————————–

Bonemeal, old leather and other organic stuff was used for case hardening gun parts, however it was not just heating the metal and dipping it like we are talking about above. The parts had to be buried in a tray of bonemeal etc and then had to be kept at red heat for several hours, this not only made a good depth of hardening but also gave the gun parts a nice colour depending on what was used.

[Adrian NicolsonParticipant @adriannicolson]

Hi Baz & All,

For Info: There were three variants of Kasenit, summarised below:

Kasenit No.1 was: "A specially refined Compound recommended for high-class work"

Kasenit No.2 was: "For ordinary shop use"

Kasenit No.3 was: "For Case Hardening in closed boxes"

All the above information was taken directly from my 1971/2 Copy of the: Buck & Hickman Tool Buyers Guide.

…thats back in the days when Tool Catalogs were crammed full of useful and pertinent information…

Regards,

Adrian

[vic neweyParticipant @vicnewey60017]

I've still got some Kasenit from way back in the 1980's, it's not in it's original container which was a yellow tin, it just corroded away so it's been in a plastic container for years.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Baz on 06/02/2022 17:24:53:

… There used to be two versions of Kasenit, numbers one and two, I don’t know what the difference was, I always used number two, I am sure someone will enlighten me before the day is out.

I found Safety Data Sheets for №1 and №2. №1 was for fine work and is Potassium Ferrocyanide. №2 was for ordinary work and is Sodium Ferrocyanide. There was a №3 too: heated in closed containers so I guess it was dangerous, and withdrawn many years ago. I couldn't find an SDS for it.

Potassium and Sodium Ferrocyanides have similar properties. They're not poisonous, but avoid breathing the hot fumes. Potassium is more expensive than Sodium. Both work by breaking down when heated in contact with Steel to release Carbon and Nitrogen, some of which dissolves into the surface of the steel and hardens it. Carbon and Nitrogen harden in different ways, which is good. Presumably the Potassium salt performs better than Sodium, perhaps because the reaction occurs at a lower temperature.

I found an explanation as to why Kasenit disappeared on the Hobby-Machinist forum with the ring of truth. Ferrocyanides are cheaply made from Hydrogen Cyanide, which is extremely poisonous. Suggested that the source of Ferrocyanides dried up when the chemical industry decided shipping Hydrogen Cyanide was too risky and switched to consuming it at the point of production. Unfortunately, there's not much call for Ferrocyanides, so firms like Kasenit couldn't buy cheap Ferrocyanides or make their own. Things may have changed but I couldn't find a supplier of Technical Grade Sodium Ferrocyanide on the web. High purity Food/Lab Grade is available, but at about £5 for 25g it's far too expensive to use as a hardener.

I don't know what alternatives to Ferrocyanides are used in case hardening compounds, but there's a wide choice – anything with Carbon or Carbon and Nitrogen in it, like charcoal and leather.

Dave

[Clive HartlandParticipant @clivehartland94829]

As mentioned before I have used a made up hardening compound using old leather cut up into small pieces, heating part and dipping into the mix. It burned well and with two sessions gave a good surface hardness.

This part was the indexing lever for a pistol and worked fine for the time I had the pistol.

[KWILParticipant @kwil]

Knighton Tools do not list Kasenit, but BETA, which is what is now generally available. It works OK.

EPK and others, Blackgate etc.

[bernard towersParticipant @bernardtowers37738]

As my case hardening is all small parts sub 3 mm I have always had great success with box hardening. The parts come out pristine and a beautiful grey all over

[JAParticipant @ja]

Dave

Thanks for pointing out that Ferrocyanides (and Ferriccyanides) are not poisonous. The Ironcyanide radicals are very strong and can only be broken by high temperatures. They are less toxic than Sodium Chloride and are used to coat table salt to make it free running!

I don't think the chemical industry is really worried about moving extreme poisons around the country. They do risk assessments etc. and things like nasty cyanides are destroyed by nature quite rapidly (the bacteria that breaks down cow shit love cyanides). I have seen a railway tanker of HF parked up at Temple Meads, Bristol. It was about 30 years ago but …..

I suspect Kasenit stopped making case hardening compound because there was no demand.

I still have my tin of Kasenit, some used, bought about 15 years ago. And it works.

JA

[Rick HannParticipant @rickhann79631]

Posted by DMB on 06/02/2022 22:05:23:

Ground up bone used to be used – bonemeal from garden centre?? Could be cheaper. I have also seen a recommendation for sugar as that is mainly carbon and it is the carbon that's needed. Don't understand why someone recommended that as it's flammable!

If you decide use bone meal from a garden center, make sure you are well away from civilization. I tried bone meal in a failed attempt at color case hardening. My workshop is in the basement. Before i realized it, the stench was terrible. It took a couple days for the smell to go away and as an aside my wife was pissed. If you use it outside you are likely to hear from the downwind neighbors! Just saying! Rick

[Clive FarrarParticipant @clivefarrar90441]

I am surprised that no one has mentioned charcoal or fire briquettes.

As I have a coal fire there is lots of the latter in the coal bunker. Put a piece in some folded over old jeans, whack it plenty of times with a lump hammer.

Use the ensuing dust for either dipping or packing..

I tried the dipping method with 3 repeats and it worked for me.

Regards Clive

[Mark RandParticipant @markrand96270]

Adding barium carbonate to the charcoal wil make it work more rapidly.

[Mike WaldronParticipant @mikewaldron61652]

So – if one is making collets out of mild steel, and then case hardens them …. Is there any need to temper them?

after all BMS isn’t brittle, is it?

 

Mike

Edited By Mike Waldron on 22/12/2022 09:27:11

[JasonBModerator @jasonb]

You don't need to temper anything that is case hardened as the core's carbon content is not altered. It just gives a wear surface

[Martin KyteParticipant @martinkyte99762]

At first glance, like when I started model engineering, it’s easy to assume that case referred to the creation of a hard skin ‘encasing’ a component. Later reading revealed that the process used to be done by enclosing the part in an iron box or “case” ? with carbon bearing materials like bone or leather. So maybe the term case hardening referred to the box. I have heard it named box hardening. This is surmise on my part so I would be interested in comments.
On a somewhat more practical and up to date point it is possible to selectively harden parts of components by choosing when in the machining sequence the casing or carburisation is carried out. For example on a part with a fine screw thread or something that will distort when heat treated like a cam follower bucket if the area to be hardened is finished machined but the rest is left oversize the part can be carburised but not quenched. The surfaces to be left soft can be skimmed, thread cut or fully machined to remove the carburised surface. Heating and quenching will harden the target surface and leave the rest soft to ensure non brittle threads or in the case of the cam follower the ability to turn the outside cylindrical after hardening has distorted it.

regards Martin

Edited By Martin Kyte on 22/12/2022 10:00:11

[bernard towersParticipant @bernardtowers37738]

Yes Martin you are quite right about box hardening, I use a it fir small-gears and other instrument parts. Not only do they come out a beautiful shade of grey but as some parts have thin star shaped teeth there is no chance of overheating as they are protected by the canister. Out of interest I put a brown paper tube in the canister to use up the oxygen which results in the nice clean finish

[Bruce VoelkerdingParticipant @brucevoelkerding91659]

Dalboy, – by the dimensions you stated it sounds like you are talking about Eccentric Rods. If those are the parts you are working on, you only case harden the small end – not the entire part. The case hardening is only to provide a long-wearing surface on the 1/8" (?) dia hole on the one end. You only heat that end and dip it in the powder. I would have a scratch rod to make sure the powder gets into the small hole.

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