Problem with 'O' Ring Tolerance?

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The discussion revolves around the challenges of achieving the correct tolerance for an 'O' ring with an internal diameter of 4 mm, where the tolerance is ±0.15 mm. The user calculated that a shaft diameter of 4.15 mm results in an 'O' ring stretch of 7.79%, exceeding the allowable limit of 5%. They sought advice on whether industries typically compromise on stretch limits for small ID 'O' rings. Recommendations included consulting with 'O' ring manufacturers for specific tolerances, which may incur additional costs. Ultimately, the user found a manufacturer that could meet their required tolerance, resolving their issue.
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It may seems like simple homework question but it is industrial question with actual condition & I am struggling for the answer & also asked this question on other website but not get any reply. So ,please help me

'O' ring Internal Diameter(ID) ID=4 mm with tolerance is + & - 0.15mm. Tolerance as per in most of the standards.
I design shaft of 4.0+0.15=4.15mm for maintaining minimum stretch of 0.00mm in any condition.
If Shaft dia is 4.15mm & minimum 'O' ring ID is 4-0.15=3.85mm then 'O' ring stretch is 4.15-3.85=0.3mm.
'O' ring stretch percentage is 0.3/3.85 * 100=7.79 % > 5% alowable limit.

Please tell me is there any other solution for this OR all the industries make compromise in stretch with small ID 'O' ring.
I not gives any tolerance on shaft. If I will give then Stretch increase more & so intensify the problem.
 
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I am not sure where the 5% allowable stretch limit came from, but if you must meet this, I would recommend to talk to the o-ring manufacturer and see if they will deliver a batch with the tolerance you need. There will probably be a price adder as they will have to sort and measure their inventory.
 
In Parker 'O' ring handbook, Dichomatik 'O' ring handbook & Eriks 'O' ring handbook Stretch limit given as 5% maximum. However, I tried to contact so many industries from last 3 weeks & finally I find one which gives me desirable tolerance which I required. So, my problem is solved.

Thanks for reply
 

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