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ET: Engine (Twin) Gearbox pinion hardness

Vincent Brake

Well Known and Active Website User
VOC Member
Dear All,

i know what the EN36 material is, how to carbonize, how to harden Et All.
but cant find a Hardness in HRc mentionend nor here nor in Withtakerpedia. Or de we leave that to the heat treatment company??
This is for the gear box parts
anyone who can give me a clue?

Btw. looking up the W. pedia took me an other night no sleep amazing

Cheers
 

John Appleton

Well Known and Active Website User
VOC Member
Dear All,

i know what the EN36 material is, how to carbonize, how to harden Et All.
but cant find a Hardness in HRc mentionend nor here nor in Withtakerpedia. Or de we leave that to the heat treatment company??
This is for the gear box parts
anyone who can give me a clue?

Btw. looking up the W. pedia took me an other night no sleep amazing

Cheers
Hello Vincent, it seems that Rc62 is the maximum after carbonizing. See http://www.interlloy.com.au/our-products/case-hardening-steels/en36a-case-hardening-steel/ for the source of this info. John.
 

Sebastian Huber

Well Known and Active Website User
VOC Member
Hello Vincent,
confirm HRC 62 as John said. Important is demand for deapness of hardening coat. This alloy 14NiCr14/15NiCr13 (both are sold under 1.5752) is perfect for coat hardening but be aware of the risk that details of your profile will get full through hardening when smaller/thinner than 3 mm.
Do you have some machining allowance in the hub bore for grinding job?
Hard Surface after grinding of 0.6 +0,2 mm is enough. So add thickness of machining allowance and you`ll get demand for deepness/thickness of carbonizing zone.
Should be 0,8 +0.2 mm, maximum +0,4. HRC 60 +2.

For pinions, even for crank pin or big end pins I use nothing but 1.7147, 20MnCr5 (old German name EC100) with same demands for head treatment.
Strength of core is a bit lower but this provides reduced risk of cracking by micro cracks caused in hardening proces.
Crucial is whether the company for heat treatment is familiar with the material you bring.

Sebastian
 

oexing

Well Known and Active Website User
VOC Member
Salü Vincent,
not quite knowing the shape of your items I would not go higher than 60 HRC, 58 will be allright, as when you look up bearing details in SKF literature they accept anything above 58 HRC for full load calculations - without allowances due to low hardness.
Whenever you have to deal with delicate parts that need case hardening you better only do minimum machining - roughing - and keep a minimum of one millimeter on all dimensions - except on faces that you like to have case hardened. So you ask just and exclusively for carbonising the parts BUT NO hardening yet. After that collect your parts, machine them to final or grinding sizes and only then send them for vacuum/inert gas hardening.
My conrods were 1.6587 , case hardening steel, 18CrNiMo7-6 . You can get it from our Ebay as well. You are busy with your starter mod ?

Vic
1.6587
 

Sebastian Huber

Well Known and Active Website User
VOC Member
Hello again,
customer demands for Heat Treatment.
Sorry, it's German.
1564463703056.png
Procedure as described by oexing is particularly used for sprokets when hub profile should be hard.
Did it last on new clutch basket for my Inter. Only inner dia. for ball bearing and contact shape for discs ratchets needs hard surface not outer dia for sproket profile.
Don't use this when non hardening profile/areas are not circulary symetrical to hard ones. You will get lots of warpage.
Sebastian
 

Vincent Brake

Well Known and Active Website User
VOC Member
Ja Sebastian, ich kanns lesen ja :D kein problem.

Ich habe ein Getriebe gekauft wass in einem brand war.
sorry, uk here:
I purchased the inners of a gearbox, which was in a fire, the alu did warp but not molten, i thought i get away with it, but all has been over 300 degrees,
so it softned.
now the re-casing will be not nessecary, as the carbon is still there.

after your advice, i think to reharden it by heat up to 780-800 degr, cool in oil and temper at 150-180 or so to reach 58-60 Hrc. and not go all monty to 62
maybe i should do refine the grain, (from 880 degr/cool in air) dont know yet, as it is old steel.


Thanx again Guys
 

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