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#904 - 06/12/12 01:42 PM maximum coverage
rseppi Offline
Member

Registered: 02/28/06
Posts: 7
Loc: seattle washington
is there a maximum coverage allowance when peening to intensity? 100% coverage is minimum when not specified by the drawing.Most aluminum is 100% and most steel and titanium call for 200% coverage. when peening to meet surface finish requirements we are allowed up to 600% when air blast peening.
is 200% the maximum allowed coverage when running automated equipment? BAC 5730 referenced

thanks


Edited by rseppi (06/12/12 02:00 PM)

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#905 - 06/12/12 03:47 PM Re: maximum coverage [Re: rseppi]
Socrates Offline


Registered: 02/20/06
Posts: 105
I am not qualified to give an authoritative answer to your several questions. My thoughts are that you should aim for "full coverage" unless instructed otherwise. "Full coverage" is defined as being at least 98% denting of the surface. It is recognised that it is very difficult to obtain accurate measurements of coverage above 98%. 200% coverage can be regarded as peening for twice the time required to achieve "full coverage". Personally I feel that 600% coverage is excessive and runs the danger of overpeening the component. Perhaps you could amplify what you mean by "peening to intensity" - it is not a phrase that I am familiar with.

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#907 - 06/13/12 08:47 AM Re: maximum coverage [Re: rseppi]
Jack Champaigne Offline


Registered: 04/20/99
Posts: 313
Loc: Mishawaka, IN, USA
First, you need to qualify intensity of the process using Almen strips and then you can concentrate on coverage. Typically full or 98% coverage is directed to be the minimum. I have not seen any directives limiting the maximum coverage (although I certainly would be in favor of such a notations). I was not aware that BAC 5730 had a 200% maximum. Do you know where this is stated in their document?

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#909 - 06/13/12 10:07 AM Re: maximum coverage [Re: rseppi]
Walter Offline



Registered: 05/03/99
Posts: 158
Loc: East Hartford, CT, USA
All you can do is to assure that the part has full coverage in the areas designated to be peened. Determining anything other than full coverage is impossible! Stating anything other than full coverage on the engineering drawing or your certification is of great concern! (both are done now on a daily basis throughout the industry) how would you prove there is exactly 100 or 200% coverage if asked?
Technically, if there is too much coverage, other problems such as rolled edges or silver streak will appear which would be cause for rejection.

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#913 - 06/14/12 09:53 AM Re: maximum coverage [Re: rseppi]
rseppi Offline
Member

Registered: 02/28/06
Posts: 7
Loc: seattle washington
thanks for the input it was helpful.

I did not mean that boeing had a max call out of 200%. I was just letting you know to which spec my question pertained.

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