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#1380 - 07/06/18 10:11 AM Saturation in case of multiple Almen strips .
PURUSHOTHAMREDDY Offline
Member

Registered: 07/06/18
Posts: 5
I am using more than one Almen strips on the same fixture for an impeller.In this case I am achieving 3 different intensities on 3 Almen strips.Which intensity should I consider?

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#1381 - 07/06/18 11:24 AM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
Dave Barkley Offline


Registered: 04/13/11
Posts: 43
Loc: USA
If you found 3 different intensities via 3 different saturation curves the answer is to use all 3 of them. The reason they put multiple strips on the part is to check that the intensity is correct in specific areas.

Each location can have it's own intensity requirement, or all three can be the same. All three locations must be within their accepted intensity band.

So make sure to determine the intensity for each location via a saturation curve. I stress this only because I frequently find people that confuse intensity and arc height (or target arc height).

Let us know if you have any follow-up questions.
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Dave Barkley
EI Shot Peening Training

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#1382 - 07/07/18 10:06 AM Re: Saturation in case of multiple Almen strips . [Re: Dave Barkley]
PURUSHOTHAMREDDY Offline
Member

Registered: 07/06/18
Posts: 5
Thank you David for the reply,however in my case all the 3 locations have the same intensity range and I am able to achieve them.Time at T is different for the three locations,during production which of the times should I consider for verifying intensity.

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#1383 - 07/07/18 12:15 PM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
Dave Barkley Offline


Registered: 04/13/11
Posts: 43
Loc: USA
Per J443, you are not required to use T as your verification time. If you use some other time you wouldn't expect the arc height value to be the same as the intensity value.

Using the curve you could select a time (after T) and see what the arc height should be for that time. You would then verify intensity by running a strip at your selected time with the goal of getting a "target arc height". If you succeed in doing so, you are verifying the saturation curve is still valid, thus the intensity has not changed.

Using this method you would take the longest T value of your 3 solved curves and find the arc heights for that time on the other 2 curves. This allows you to verify all 3 locations with a single time.

We describe this procedure at our US Workshop and international seminars. Come out and see us at one! smile
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Dave Barkley
EI Shot Peening Training

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#1384 - 07/08/18 08:51 AM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
PURUSHOTHAMREDDY Offline
Member

Registered: 07/06/18
Posts: 5
Thank you David

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#1385 - 07/10/18 10:20 AM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
PURUSHOTHAMREDDY Offline
Member

Registered: 07/06/18
Posts: 5
I could set target arc height.So I could understand from your reply that I can verify intensity at the time corresponding to target arc height during each production run.Is this enough?

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#1386 - 07/10/18 10:22 AM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
PURUSHOTHAMREDDY Offline
Member

Registered: 07/06/18
Posts: 5
What is the variation permitted from the established intensity,is it + or - 0.0015?

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#1387 - 07/10/18 10:38 AM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
Socrates Offline


Registered: 02/20/06
Posts: 103
The concept of "Target Intensity" is explained in detail in the 2015 TSP article "Verification of Peening Intensity" - downloadable via Shotpeener.com/library - bottom of page 1.

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#1388 - 07/10/18 10:52 AM Re: Saturation in case of multiple Almen strips . [Re: PURUSHOTHAMREDDY]
Walter Offline



Registered: 05/03/99
Posts: 155
Loc: East Hartford, CT, USA
The allowed variation in J443 is ± 0.0015"

A word of caution other peening specifications imposed other limits. Such as AMS2430 which require the ± 0.0015" variation to remain inside the limits of the engineering drawing.

AMS2430 example:

Drawing states the intensity range to be .006-.009A. During your process development you determine that the intensity of your process is .0085A. Now sometime later you run your verification arc height.
Based on AMS2430 it can be as low as .007A but the upper limit is .009A.

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