14.625 inches nominal dimension before proof load testing. tolerance is applied after proof load testing. part will be proof loaded @1,200 lbs. dimension after proof load test will be 14.625 +/- .062 inches please interpret to me this procedure . is the 14.625 nominal dimension is supposed to be the actual dimension to be made before proof loading?
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mechanical print of a wire cable assemprocedurebly interpretation
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MikeHalloran
Mechanical
Uh, _what_ procedure?
All I see is three circularly worded lines of gibberish with uncertain punctuation.
Please quote the exact text of the procedure so that we may properly understand your concern.
Mike Halloran
Pembroke Pines, FL, USA
All I see is three circularly worded lines of gibberish with uncertain punctuation.
Please quote the exact text of the procedure so that we may properly understand your concern.
Mike Halloran
Pembroke Pines, FL, USA
Sounds like the important thing is that after proof load testing, the part must measure 14.625 +/- .062.
This is similar to a 'restrained condition' type note as opposed to the dimension applying free state. It's an approach that can complicate inspection but done properly will increase yield &/or captures part functionality more completely.
This may be a case where you need to iterate the assy process/pre test length a little to optimize yield - you could build some at nominal, measure the actual assembled length of each before test, measure each after test and see what the stretch is. You could then apply a 'correction' to the pre test length of future units e.g maybe you make them at nominal 14.600 or similar.
This is similar to a 'restrained condition' type note as opposed to the dimension applying free state. It's an approach that can complicate inspection but done properly will increase yield &/or captures part functionality more completely.
This may be a case where you need to iterate the assy process/pre test length a little to optimize yield - you could build some at nominal, measure the actual assembled length of each before test, measure each after test and see what the stretch is. You could then apply a 'correction' to the pre test length of future units e.g maybe you make them at nominal 14.600 or similar.
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What is Engineering anyway: faq1088-1484
What is Engineering anyway: faq1088-1484
I'm assuming this is a cable assembly with some type of swaged fittings at each end. These would be similar to control cables used by aircraft. MIL-DTL-5688 covers proof testing and prestretching of aircraft wire rope assemblies, so it might worth looking at.
All newly manufactured wire rope has some inherent amount of constructional stretch, and prestretching will remove it. Wire rope is often supplied prestretched by the manufacturer, but this is not always the case. I think the intent of the drawing was to account for wire rope that was not prestretched prior to assembly. A better approach might be to inspect the length of the cable assy using a gage load, both after prestretching and after proof testing, to check for any slipping of the end fittings. Slippage of swaged end fittings in proof test is usually cause for rejection.
All newly manufactured wire rope has some inherent amount of constructional stretch, and prestretching will remove it. Wire rope is often supplied prestretched by the manufacturer, but this is not always the case. I think the intent of the drawing was to account for wire rope that was not prestretched prior to assembly. A better approach might be to inspect the length of the cable assy using a gage load, both after prestretching and after proof testing, to check for any slipping of the end fittings. Slippage of swaged end fittings in proof test is usually cause for rejection.
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