heat treatment

[Hybrid_From_Hell]

For those who know please edification me lol

Am musing an idea of an arb enhancement. ..so say I get it made via cnc to be a perfect fit...and let's say it's made from en24. ..

So...It fits perfectly. ...now I get it heat treated and it changes

Dimensions a little bit....

HOW do I calculate what that little bit is ????

[Big.Mike]

It depends on the shape, size of the part.

For example the half-shafts Quaife used to make had to be straightened after each time they were submitted to any sort of work. But they were long.

Pinions weren't undersized as a rule iirc.

Cheers,

Mike

[steve b]

It's not just the size and shape , but also the level of heat and the cooling method , ie air cooled / quenched - in what ? .

Are you looking for hardness or toughness? Is it a bearing surface? lots of variables , Nige . For a start I'd talk to your local

Heat treaters , in my area Middleton Heat Treatment do lots of gears and shafts as well as Boron Ag stuff

hth

Steveb

[Cynic-al]

If the size or finish is important you could get it ground / polished afterwards.

[Hybrid_From_Hell]

Will be required to take a token bearing if that helps

[Big.Mike]

If the size or finish is important you could get it ground / polished afterwards.

As said for a bearing fit, grinding/polishing is what you want.

[Team Idris]

Or make it with a slide-fit tolerance and glue the bearing in? Technology is your friend today! It lets you design things that Victorians had to spend hours lapping together.

But as mentioned, it always looks to be about warping as the stress is relieved, rather than a size change.

[Big.Mike]

Or make it with a slide-fit tolerance and glue the bearing in? Technology is your friend today! It lets you design things that Victorians had to spend hours lapping together.

But as mentioned, it always looks to be about warping as the stress is relieved, rather than a size change.

Depends what type of bearing it is, some rely on a good hole.

[Cynic-al]

I guess depending on the part and steel you could have it normalised, machine it, have it hardened then get the important bits ground? Or rough machine it, normalise it, finish machine it, harden it then grind it. But how important is it?

I've used nitride hardened parts before with a quoted hardness of 1400n/mm2 which is meant to be done at a lower temperature to reduce distortion.

[vulcan bomber]

from what your saying, i'd use EN36C or s155 or s157.. Machine, carburise, remove anything you've carbon jacketed (threads ect), harden, grind, put together and sell, it will "creep" a bit but it depends what your after.

Nitrided EN40B is pretty tough as well, grinders struggle with nitriding its that hard.

[Troddenmasses]

I work with this industry and there really is no easy answer to that question. The best thing to do is to give your local place a call and ask to speak to a technical specialist or laboratory manager - they are the people who actually know about the process, rather than being the bloke who sticks metal into furnace trays. If you can remind me where in the UK you are, I can probably point you in the direction of a good heat treatment place, and if you are in the Midlands or South West, will be able to tell you the best person to speak to.

TM.

[Daan]

it will grow a few thou, but not neccesarily a problem. I would get one of your proposed parts made and measure before and after. Then re adjust the macining dimension afterwards if needed. I had my winch shaft case hardened, it was a bit of shaft of a standard size with a few keyways machined into it. I fitted fine to the bearings, if not a bit tighter. As mentioned before, EN36 is the spec to go for. Heat treating EN24 is a bit wasted effort.