Ring Gage Thermal Expansion

[SMcNearney]

Hello Everyone,
Thank you in advance for reading my post. I am having a discussion with a colleague about the thermal expansion of ring gages. I've done some preliminary research already, and have found nothing concrete and i'm hoping some of the experts on here would be able to assist me. I am an ASQ Certified Calibration Technician with 12 years metrology experience, and although i have tried very hard to research everything i was initially taught (many of the initial things i have found to be wrong), i still can't find definitive evidence. I was originally taught that the thermal expansion of ring gages were opposite just like the tolerances of the plugs. Ie: when a ring gage gets warmer, the internal diameter becomes smaller, and when it's colder, the diameter gets larger. I've tried reading through Puttock and Thwaite’s CSIRO Technical Paper No. 25, however it alludes mostly to spheres, pins, and plugs. It does mention the compression factor, which would actually defer the expansion to be the same as any other linearly dimensional object, like gage blocks, but i am still not sure. Does anyone have anything concrete on this, or can share personal experience? I do have access to ASME B89.1.6 however it's not as clear cut as i'd like. Thanks again!

 

[Miner]

An interesting question to which I do not have the answer. From a physics perspective, higher temperatures should increase the diameter of the neutral axis. However, you would also get an increase in the cross-sectional thickness, so I'm not sure which would win out. I would probably try an experiment with three different temperatures to find out. Thin walled pipe definitely get larger.

 

[CCaantley]

From what I've read, since all the material will expand under heating, the hole will also get bigger. That would explain why if you run a jar lid under hot water it loosens. Just my , which could be worth nothing in the end.

 

[dwperron]

The hole expands.

And if you need proof (like I did) then here is a short video:

And think about how you get a bearing onto or off of a shaft.
You heat it to expand the bearing.

 

[John Predmore]

The answer to this riddle is that all linear dimensions (length, inside diameter, circumference) of the object increase proportionally with thermal expansion (assuming uniform change in temperature).

If you heat a ring of metal, does the inside diameter shrink or grow?