How strong is a crimped fit?

[Guzrik]

Another school scrapheap skelter challenge team race for my son.
They have changed an alternator to drive the skelter, estimated power is 3.5kW (?!) at 3000rpm.
To reduce the rpm's he came up with an extra shaft.
On one end (big sprocketwheel) he milled a conical square but the small one was only crimped on with a negative play 0.05mm.
The small wheel (ID 15 mm) was heated to redhot (300-350C?) and then slided over easy.
It will be tested soon and I will report back here, but what do you think?
Will this hold, race will be one hour?

 

[Kram]

A shrink fit like that is not coming off.

 

[zzr1200]

2 thou interference fit, Hmmm.

I'd use a good dab of agricultural lock nut on it as well... you can alway remove the larger chain wheel and pop the shaft in a lathe to undo it....

 

[Other Daniel]

Why not put a roll pin through as well ?

 

[Guzrik]

2 thou interference fit, Hmmm.

I'd use a good dab of agricultural lock nut on it as well... you can alway remove the larger chain wheel and pop the shaft in a lathe to undo it....

Yeah once it was on we also wish we had done more, but if that would've been better? How much would be possible with a 15mm shaft?
Loctite doesn't go with hot crimp?
@Other Daniel; drilling weakens the shaft as well?

 

[Erie Fred]

Why not put a roll pin through as well ?

That messes up the shrink fit.
Not needed, causes problems.

 

[Erie Fred]

Yeah once it was on we also wish we had done more, but if that would've been better? How much would be possible with a 15mm shaft?
Loctite doesn't go with hot crimp?
@Other Daniel; drilling weakens the shaft as well?

Might be the language xlation, but the term is normally "shrink fit" or "press fit".

Might help you in google searching the interference sizing.
There are charts for what you need.

Too much fit, and the outer hub will yield, and that's not really a good thing either.

 

[Kram]

I've done many shrink fits and the only time I had issue was where the outer peice was very thin, allowing it to expand and slip.

Shrink fits beat press fits, as when you press parts on, any roughness will get formed smooth. A shrink fit preserves any roughness and so has a better grip.

 

[Turbo]

Run some weld round it.

 

[arther dailey]

agree ,belt n braces , 3 spot welds jobs done with no doubt.

 

[Bornfree]

Loctite 638 would hold it

 

[Bobtail4x4]

isnt this a welding forum? glue??

 

[Bornfree]

isnt this a welding forum? glue??

Loctite 638 is liquid welding

 

[Erie Fred]

I've done many shrink fits and the only time I had issue was where the outer peice was very thin, allowing it to expand and slip.

Shrink fits beat press fits, as when you press parts on, any roughness will get formed smooth. A shrink fit preserves any roughness and so has a better grip.

interesting to watch a Locomotive wheel get pressed on at 400 tons or so.
Chart of pressure vs distance better be an even slope upwards.
If not, you've got some material removal happening.