×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Will heating destroy case hardening

Will heating destroy case hardening

Will heating destroy case hardening

(OP)

So have a gear thats a interference fit on a shaft. (by 0.08mm)
Both gear and shaft are some sort of nickel - chromium steel simular to en36a (but not necessarily so, detected composition by XRF and found closest match).

There case hardened, but not through hardened. (cutting a old gear is soft inside) But do not know the process used to harden. (suspect carburised, but its a mass produced item from a motorcycle gear box so who knows)

What to try and shrink fit assembly instead of press, But to expand the gear over the shaft would have to heat gear to a calculated 360C. Will this damage the case hardening of the gear? and any ideas as to what max temperture could be used used.

RE: Will heating destroy case hardening

Assuming you have a steel close to EN36A, see the attachment. You have core hardness data after carburizing and another table showing the typical hardness after tempering at 200 deg C. These is a slight drop in hardness at 200 deg C.

I would limit the heat to less than 200 deg C to avoid softening the case.

http://www.interlloy.com.au/our-products/case-hard...

RE: Will heating destroy case hardening

Instead of heating the gear, why not deep freeze the shaft instead?

RE: Will heating destroy case hardening

or both

RE: Will heating destroy case hardening

(OP)

I don't think slip fittings going to fly, after all.

Heating to 200C will expand by +.04mm
Freezing with dry ice -78C contract by -.02mm
Not enough need at least .09mm difference to be desirable easy slip on.
Could freeze with liquid nitrogen at -195C will contract maybe -.05mm,
so heat and freeze potentially works, BUT would have to buy nitrogen, not worth the expense, can just press it on... (Dang! need a bigger press!)

RE: Will heating destroy case hardening

and if a bigger hammer won't fix it, your problem is electrical

RE: Will heating destroy case hardening

Liquid nitrogen should be relatively cheap - in central FL, the suppliers sell it by low volume amounts (less than 2 liters) for shipping bull semen.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close