[TheForge] Timken Case Hardening was File Making

[Peter Fels And Phoebe Palmer]

Wow!...thanks Dave....pf

David E. Smucker wrote:
> Mike,  To the best of my knowledge, Timken's process was a carbon based 
> case hardening.  I worked a lot with Timken in the 90's on the 
> development of a new bearing design for rolling mills.  Timken did the 
> development work and we (Alcoa) did the mill design / field testing.  I 
> got to see a lot of Timken's operations from the steel making to bearing 
> manufacture and testing.  Interestingly Timken considered their case 
> hardening process one of their area of special technical knowledge and 
> would talk very little about it.  We could walk by the equipment, and 
> they would say "this is where we case harden the bearing races" and then 
> they would say "that is all we are going to say about it".  I 
> understood, we had gauge, profile controls, and rolling lubrication that 
> we would not talk about.  They would show etched cross sections of the 
> races to show the depth of the case -- it was deep.  One thing you can 
> do with very large roller bearings (56 inches OD for example) is regrind 
> the inter and outer races and put over size rollers and get a second 
> life out of the bearing.  We had Timken's largest bearings (about 80 
> inches OD) on our big plate mill at Davenport, IA and some of those 
> bearings where rebuilt after about 20 years in service.
> 
> Dave Smucker
> ----- Original Message ----- From: "Mike Spencer" <mspencer at tallships.ca>
> To: <theforge at mailman.qth.net>
> Sent: Wednesday, March 19, 2008 6:41 PM
> Subject: [TheForge] Re: File Making
> 
> 
>>
>>
>> Dave Smucker wrote:
>>
>>> ...the very best roller bearings are case harden, very deep case, as
>>> much as 0.060 deep and the core is a very tough alloy steel similar
>>> to 4120.  (Timken, which in my experience with very large bearings
>>> are the world's best.)  Same is true for high performance large gear
>>> sets.
>>
>> So, Dave, is that carbon case?  Or nitriding?
>>
>> When I worked in a wire mill (Michelin) the capstan drums over which
>> the wire passed in various continuous-process treatments had to have
>> absolutely minimal wear since if one drum's diameter differed from
>> another in the train or differed from one point to another along its
>> surface, the wire speed wouldn't be consistent and there would be
>> breaks, sags or snarls. So the the drums were machined to matching
>> size, heated for hours (days? I forget) in a nitrogen atmosphere and
>> then, if needed, finish ground to match with an optical comparator.
>> They still didn't last forever but, according to the shop scuttlebut,
>> they wouldn't have lasted a day without that treatment.
>>
>>
>> - Mike
>>
>> -- 
>> Michael Spencer                  Nova Scotia, Canada       .~.
>>                                                           /V\
>> mspencer at tallships.ca                                     /( )\
>> http://home.tallships.ca/mspencer/                        ^^-^^
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