Harden the camshaft and crankshaft.

[minh-thanh]

Harden the camshaft and crankshaft.

Hi everybody !
I looked at the information on the internet and included videos of the machine it uses for hardening..
I have a question , how to reduce warping shaft during hardening - especially those made from one piece ?
What is the hardening temperature ? Should I use water or oil?
We are not discussing necessity or not. It's just that I like to push my hobby, it's like "a game of conquering challenges"
Any comments are welcome !
Thanks .

 

[aonemarine]

Temp, water, oil.. all depends on the alloy..

Typically you would use 8620 steel for the cam and crank and rough machine it leaving .002"-.005" for finish grinding after heat treatment.. Sometimes you'll need to straighten the part after heat treatment before finish grinding...
4140 might not be a bad choice either, as it can be hardened fairly easily, machines pretty well, but doesn't have the abrasion resistance 8620 can...

 

[minh-thanh]

A useful piece of information .
Thanks !

 

[JtH]

Harden the camshaft and crankshaft.

Hi everybody !
I looked at the information on the internet and included videos of the machine it uses for hardening..
I have a question , how to reduce warping shaft during hardening - especially those made from one piece ?
What is the hardening temperature ? Should I use water or oil?
We are not discussing necessity or not. It's just that I like to push my hobby, it's like "a game of conquering challenges"
Any comments are welcome !
Thanks .

I am running on archival footage here, but the machinery handbook used to have very useful information on hardening processes in the workshop.

 

[mrehmus]

A crankshaft of 4130 doesn't need hardening. The Black Widow V-8ss have been running for 10 years with crankshafts of that steel. 4030 is a good choice for the cam. You can harden it to about 55 Rockwell and that is the cam used in the V-8s. Put the cam in a drill press before you grind it and heat each of the cam disks to red heat and then plunge the metal into a saline solution while it is turning. Minimum distortion. Then you grind the cam.

 

[aonemarine]

We are not discussing necessity or not

A crankshaft of 4130 doesn't need hardening.

I took things as a question on how to do it, rather than the necessity, that's all..

 

[peterl95124]

Minh-Thanh, if you've already made your crankshaft and camshaft then its a question of what alloy(s) did you use, if not then you have lots of choices, but like Mike Rehmus said folks have been running 4130 (and 1144) crankshafts unhardened AOK. The problem with hardening a crankshaft is that its going to distort no matter what alloy is used and no matter what heating and quenching technique is used, which means...

... if you do harden your crankshaft are you prepared to grind and polish the journals to final dimensions afterwards, IE do you have a tool post grinder for you lathe ? and maybe a CBN grinding wheel as my experience with corundum is that you won't get a level surface unless the wheel is narrow enough to traverse left and right while grinding to even things out as otherwise the corundum doesn't wear evenly.

which is why I looked into nitriding, a surface hardening treatment like case-hardening, but using nitrogen instead of carbon, which can be done at temperatures lower than what causes distortion, but found that its not really a DIY process and not really affordable to have done, darn !!!


expanding on what Mike Rehmus wrote, the nice thing about 4130 for cams is that the carbon content is low enough that after water quenching it does not need to be tempered just use it as is and it will not be too brittle (but anything with higher carbon will be too brittle and will have to be tempered after quenching).

another thing, have your drill press on low speed if you're using one, I didn't and the results were more bend than could be ground out. On another occasion using low speed there was still a bit too much bend, but because the space between the cam disks didn't get very hot they were soft enough that I was able to un-bend the hardened cam blank before grinding, doesn't always work, I also broke one, but I succeeded 2 out of 3 and I only needed 2.

on my next engines I'm trying A2 (air hardening tool steel) for cam shafts, which shouldn't ever distort more than can be ground out during final grinding, but sticking with un-hardened 4130 for crankshafts.

 

[Steamchick]

On nitriding. I don't know if this works, but....
Medieval texts explain tricks used by blacksmiths... One I remember stated that feeding donkeys on turnips and collecting their liquor (urine) makes a better hardening solution on the quench tank than using well water. Apparently the nitrogen in the urine does a crude form of nitriding. A modern version (from other things I read, but have not proved) explained that high nitrogen fertiliser used instead of case-hardening powder gives a harder finish.... but I don't know at what temperature....
Commercial nitriding of steel wire piston rings (after shaping) uses a gas oven to heat the parts to just below a dull red heat... then feeds ammonia as combustion gas into the burn to make a nitrogen rich atmosphere from the NH4, N2 and O2 (from air) producing lots of N2 and water....
Maybe a suitable blowlamp could use ammonia instead of regular hydrocarbon fuel gas?
I think the temperature is critical to do any of this!
K2

 

[minh-thanh]

Thanks for the comments and advice!
That is Great , again Thank you .

I took things as a question on how to do it, rather than the necessity, that's all..

Maybe ....it will be useful in the future or useful to others .

I am thinking and looking for a way to limit the warping of the shaft when hardening . and Maybe I will use high frequency to heat .

 

[Steamchick]

Clever if you can do it. Induction hardening uses high frequency oscillating magnetic fields. Good for localised hardening, e.g. Parts of stub axles on cars. But for a crankshaft, I would use a muffle furnace, to slowly heat and cool the whole shaft through a controlled cycle as per text book heat treatment processes. Times and temperatures should be available for the steel you have used. The slow process avoids distortion. (NORMALLY rapid temperature changes cause differences in temperature across components and create distortion.).
But I am not an expert, just auditor of processes and resulting components.
K2

 

[minh-thanh]

Hi K2 !
I don't think it's too difficult
The problem is how to reduce shaft warping when hardening is as low as possible, and make a machine that can harden both camshaft and crankshaft.
That's an idea of mine from a long time ago , a few years ago , Maybe it will be ...a design....

But I am not an expert, just auditor of processes and resulting components.
K2

Any comments are welcome !
Thanks .

 

[GreenTwin]

Temp, water, oil.. all depends on the alloy..

Typically you would use 8620 steel for the cam and crank and rough machine it leaving .002"-.005" for finish grinding after heat treatment.. Sometimes you'll need to straighten the part after heat treatment before finish grinding...
4140 might not be a bad choice either, as it can be hardened fairly easily, machines pretty well, but doesn't have the abrasion resistance 8620 can...

This is good information to know.

.

 

[Nerd1000]

Silver steel seems to be pretty good at hardening without excessive distortion in smaller diameters, as you would use for D-bits. That's what I'm making my camshaft from. You harden by heating it cherry red then quenching in water or oil, then temper it at around 200 degrees Celsius.

I plan to do the finish machining using CBN tooling on the lathe and mill, followed by polishing. We shall see how that goes on my pathetically small and non rigid mill, but on the lathe I've even been able to turn down HSS tool bits using CBN.

 

[minh-thanh]

Hi Nerd100 !

, then temper it at around 200 degrees Celsius.

Is that for stress relief ?

 

[L98fiero]

Minh-Thanh, if you've already made your crankshaft and camshaft then its a question of what alloy(s) did you use, if not then you have lots of choices, but like Mike Rehmus said folks have been running 4130 (and 1144) crankshafts unhardened AOK. The problem with hardening a crankshaft is that its going to distort no matter what alloy is used and no matter what heating and quenching technique is used, which means...

... if you do harden your crankshaft are you prepared to grind and polish the journals to final dimensions afterwards, IE do you have a tool post grinder for you lathe ? and maybe a CBN grinding wheel as my experience with corundum is that you won't get a level surface unless the wheel is narrow enough to traverse left and right while grinding to even things out as otherwise the corundum doesn't wear evenly.

which is why I looked into nitriding, a surface hardening treatment like case-hardening, but using nitrogen instead of carbon, which can be done at temperatures lower than what causes distortion, but found that its not really a DIY process and not really affordable to have done, darn !!!


expanding on what Mike Rehmus wrote, the nice thing about 4130 for cams is that the carbon content is low enough that after water quenching it does not need to be tempered just use it as is and it will not be too brittle (but anything with higher carbon will be too brittle and will have to be tempered after quenching).

another thing, have your drill press on low speed if you're using one, I didn't and the results were more bend than could be ground out. On another occasion using low speed there was still a bit too much bend, but because the space between the cam disks didn't get very hot they were soft enough that I was able to un-bend the hardened cam blank before grinding, doesn't always work, I also broke one, but I succeeded 2 out of 3 and I only needed 2.

on my next engines I'm trying A2 (air hardening tool steel) for cam shafts, which shouldn't ever distort more than can be ground out during final grinding, but sticking with un-hardened 4130 for crankshafts.

With the 4130 you can flame harden the cam surfaces only, use an oxy-acetylene torch and the drill press, heat the surface quickly to red heat and quench in oil, that hardens the surface only as deep as the red heat goes, that way the shaft part will stay soft and can be straightened if required.

 

[Nerd1000]

Hi Nerd100 !

Is that for stress relief ?

Partly. But the main reason is to improve toughness, most kinds of high carbon steel will be super brittle after quenching. Tempering slightly softens the metal and returns some shock resistance. You can fine tune your hardness this way, the hotter your tempering step the softer and tougher the steel becomes.

 

[D and D]

Chrome plating is not a bad solution IMO.

 

[Steamchick]

Providing that you do not locally heat parts of the shaft, and heat can penetrate and dissapate fully,and evenly, there should be No distortion. Distortion only occurs during temperature changes when it is unevenly appreciated by the component.
Slow oven processes do this properly, but are not good for high volume production. And oven heat treatment is uniform, whereas some parts (e,g, cams) need local hard zones and local ductile zones.
I have hardened many silver steel and tool steel things, simply using the "Red heat and quench ", followed by "old fashioned" tempering of edges after polishing the metal, by heating the "core" until the temper colour lines creep up slowly, then quenching in water when the required colour reaches the edge to be hard or sharpened. Works nicely for wood tools, cold chisels, screwdrivers, surgeons' scalpels, etc... with practice. Cams on car engine camshafts are grey iron, with "air-Quenched" cam lobes to harden them before grinding. The Grey iron core provides the ductility, while the surface hardening suits the cams/followers. (But the productioon process all takes place inside the machine so I really have no idea what to replicate!)
K2

 

[Steamchick]

D and D: I understand that for (example) cam lobes, Chrome plating can suffer fatigue problems (short lifetime) as the hard plating on a relatively soft under-material, flexes as the material beneath suffers compression loadings and distorts, so the chrome suffers early life failures due to fatigue (over-flexure cycling). Big words, but simply not good for cams other than on racing engines with short lives anyway. Case-hardened steel or iron is better for long-life engines. But I am just a dumb engineer from car engine manufacturer, not the expert who decided the rules... or made things work! So "Well done" if you succeded with chrome plated cams!
K2

 

[Roger B]

I have not hardened any crankshafts, just used a moderate carbon steel.
I have successfully made single cylinder (two lobe) camshafts from hardened silver steel just heating with a gas torch and water quenching. Longer silver steel camshafts tend to distort with this simple method and are generally too hard to straighten without breaking. I then tried case hardened mild steel which still tends to distort but can be straightened.