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#83 - 01/27/09 11:14 AM Almen strip location on gears
alfredo Offline
Member

Registered: 08/28/08
Posts: 6
Loc: Madrid; Spain
We have to shot peen a gear which teeth lenght is smaller than the Almen strip. We have always worked with bigger gears, and we usually locate the Almen strip along the gear root (middle of the teeth length). If I use a standar Almen strip, the shot will not impat along the whole strip, so I assume the Almen intensity measured will be wrong.
1š) Should I use a smaller strip?. In this case, can I correlate the results?
2š) Should I locate it in other position (not following the gear root)?
Regards

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#84 - 01/30/09 02:47 PM Re: Almen strip location on gears
Jack Champaigne Offline


Registered: 04/20/99
Posts: 317
Loc: Mishawaka, IN, USA
Can you modify your gear root to be large enough for the Almen strip? Another possibility is to simulate the gear root, mount Almen strip onto a fixture that represents the angle of impact and distance to nozzle.

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#85 - 01/30/09 03:13 PM Re: Almen strip location on gears
Jack Champaigne Offline


Registered: 04/20/99
Posts: 317
Loc: Mishawaka, IN, USA
also see this link for use of shaded strip
http://www.shotpeener.com/learning/hole.pdf

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#86 - 02/02/09 02:57 AM Re: Almen strip location on gears
alfredo Offline
Member

Registered: 08/28/08
Posts: 6
Loc: Madrid; Spain
Thank you for your quick answer.
Based on both information you have attached, I think the shaded strip option is more consistent from th quality standpoint. Am I wrong?
There is one issue I donīt really understand. In the step 1, when I am developing the process with the standar Almen strip, I assume the scaning of the nozzle has to cover the whole lenght of the strip, am I wrong?
Thanks again

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#87 - 02/02/09 01:34 PM Re: Almen strip location on gears
Jack Champaigne Offline


Registered: 04/20/99
Posts: 317
Loc: Mishawaka, IN, USA
You must scan the entire strip to establish your peening intensity. Let's put some numbers into an example. Let's suppose you need a 10A intensity and the standard size A strip will not fit the tooth root, however you are able to fit strip into the tooth root that becomes only partially covered. Obviously this strip won't accumulate enough dents to curve properly so you need to continue with an experiment.
Expose a standard size A strip to the blast stream until you can verify that you have the parameters adjusted to achieve the 10A intensity. Next, you place an A strip in the blast stream that receives only partial coverage by using hard masking to shield the ends of the strip. This strip won't curve as much as the fully covered strip but is does curve enough to give you a "relative" reading. You must now perform your peening whilst achieving this new value or relative reading.
In the event that the masked A strip does not curve very much you might decide to substitute an N strip with hard masking on ends. It will exhibit more curving because it is thinner. Whatever its curvature measures will become you target value for process control. In essence you have correlated the curvature of two different strips when exposed to the same blast stream thus allowing you to fit a strip into your limited root space.

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#88 - 02/03/09 02:20 AM Re: Almen strip location on gears
alfredo Offline
Member

Registered: 08/28/08
Posts: 6
Loc: Madrid; Spain
Thank you again.

Your explanation is clear. We will do that.

Regards.

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