Shrink Fitting

[SpecialtyTool]

Not sure if it fits in this forumn anywhere but I have a question about shrink fitting. I need to fit a shaft into a ring. The shaft is too long to freeze so I am relying entirely on heating the ring. The hole is just under 3" and the O.D. is 3-15/16" diameter in 1045 steel. I found the thermal expansion coefficients but Im concerned that since there is a hole thru that it may expand more. Anyone with any experience in this area would be a big help. I plan on heating the ring to between 300° and 400° and expect around .004' to .005" expansion as it is with the standard formula but again I wonder if it will grow more since it has a larg hole thru it. Any advise would be greatly appreciated.

[jeff]

If it grows more wouldn't this be more beneficial?

less of a chance that it would get stuck when sliding it on the shaft.

Maybe place an icepack or 2 onto the shaft where the ring is going to help?

[MotorCityMinion]

This might be a dumb question, but wouldn't the ring ID grow smaller at the same time due to expansion? Perhaps not at the same rate , but still?

[jeff]

This might be a dumb question, but wouldn't the ring ID grow smaller at the same time due to expansion? Perhaps not at the same rate , but still?

 

You would think so, but it doesn't. The entire part grows.

To exaggerate, if a part at room temperature is 1x size.. then if you heat it up it's now 2x size... OD and ID are twice as large.

Also wall thickness plays a big part of how fast/slow the ID will expand.

[HANARD]

Just pour liquid nitrogen over it......

[Mr. Wizzard]

If it helps, put one end of the shaft in a bucket of ice water.

[K2csq7]

300-400 deg seems a bit of overkill..... I have done stuff like this with 8-11" dia tubes (bout 1/2" wall) only .001-.003 <MAX interferance fit (my experience, not saying you don't need more) when I did it I would heat slowly tapping my hand on it every 20 sec or so... when it got to hot to keep my hand on it they would drop right on.

[K2csq7]

Posted 18 July 2011 - 11:40 AM

 

HANARD, welcome to the forum, but check the date on the post, I think he got this done by now...