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#452 01/07/08 07:30 PM
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Walter Offline OP
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Just thought you all might like to know that
AMS-S-13165 has been CANCELLED finally! You have to January 1, 2009 to update your process / procedures to fulfill the new requirements. Which is whenever AMS-S-13165 is called out you must work to the requirements set forth in AMS-2430.

#453 02/19/08 02:30 PM
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For users converting from 13165 to 2430 the issue of Coverage must be considered since 13165 is self-contradictory regarding coverage.

=================== technique in agreement with ams 2430 ====================================

3.3.7 Coverage: Areas of parts shot peened in compliance with design requirements shall be peened to complete visual coverage (see 4.4.1 and 6.11). When a surface on which peening is required is obstructed and it is impossible to obtain complete visual coverage by direct impact, coverage by reflected shot is allowed.

Full coverage will not be required if the part is peened only for forming or straightening. Critical applications shall be as specified by the procuring activity (see 4.2 and 6.11).

4.4.1 Coverage: Unless otherwise specified articles shall be 100% visually inspected for compliance with the coverage requirements of 3.3.7 using either method described in 6.11a or 6.11b.

6.11 Coverage: Complete visual coverage is defined as a uniform and complete denting or obliterating of the original surface of the part or work piece as determined by either of the following methods:

(a) Visual examination using a ten power magnifying glass.
(b) Visual examination using a ten power magnifying glass in conjunction with an additional visual examination using an approved liquid tracer system (see 6.17.4) may be used for process control by the contractor. Unless otherwise specified, the procedure for using an approved liquid tracer system is described as follows:

Prepare a control specimen of the actual work piece. Coat this control specimen with tracer liquid by dipping, spraying, or painting and allow the liquid to dry. Check the specimen under a light (an ultraviolet light is used for a fluorescent tracer system) to insure that complete coating of the area to be shot peened has been accomplished. This control specimen is shot peened using the correct intensity and parameters specified for complete coverage and is then re-examined under the light (or ultraviolet light) in order to determine if the tracer residue has been completely removed. Full coverage is indicated by complete removal of the tracer residue. Coverage of actual production pieces can
be established by using the same procedure used for control specimens. This can be done by utilizing the liquid tracer for each part or on a statistical sampling basis.
NOTE: The liquid tracer system must be approved by the procuring activity. Data, showing that 100% coverage of the part is obtainable by using this tracer system, is required.

6.12 Intensity: Intensity can only be established by plotting a saturation curve, as shown in figure 8, and assuring that the required intensity (determined by the arc height of the test strip) falls on the right side of the knee of the curve. By doubling the time of exposure, the arc height of a test strip should not increase by more than 10%.

===================== technique not in agreement with ams 2430 ==================================

3.3.6 Peening iIntensity: Unless otherwise specified on the drawing or in the contract, the intensity value of the shot stream used on the part shall be as specified in Table 6 for the thickness of the material being peened. If only a minimum intensity is specified, the variation from the specified minimum intensity shall be -0, +30% rounded to the nearest unit, but in no case less than 3 intensity units (A, C, or N) unless otherwise specified. For example, a specified peening intensity of 6A would denote an arc height of 0.006-0.009 inches on the “A” specimen. Shot peening of parts shall be accomplished using the same parameters (time, distance, blast pressure, angle of incidence, etc.) as used on the test strip.
[note: inclusion of "time" in the parameters list is in conflict with paragraph 3.3.7.]

========== Conclusion ====================
Your transition to AMS 2430 may or may not be in conflict with 13165 depending upon which version of coverage in 13165 you used (and coversely, which version you ignored).

#454 02/21/08 05:36 PM
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I think this post is really important in getting the next revision of AMS 2430, and all shot peening specifications for that matter, on the right track. The only misleading part is that complete coverage not always leads to complete removal of the tracer. The way to evaluate complete coverage itself is quite difficult to state. I think the tracers should be used only as an aid to evaluate coverage, as it will give a more obvious indication of surfaces where coverage may be insufficient. It is true that tracers can be removed by ricochets that doesn't produce an actual dent in the surface, becausee of the shallow angle of impingement or other reasons. Surfaces showing traces of remaining tracers shall be subjected to visual inspection (10X - 20X) to confirm or not the presence of "real" dimples.

If I understand well the way fluorescent tracer works (I've never tested those myself), you have to produce a "master" part once the proper exposure time has been determined. This master should be prepared with the fluorescent tracer, so that the operator can compare the production parts (previously coated with tracer before shot peening) with the master and compare the amount of remaining fluorescence. If the level of fluerescence is the same, the amount of coverage of the master part has been reached on the production part. From my understanding, this method still relies on visual inspection for preparation of the master part.

I think the main problems with visual inspection are:

1 - subjectivity of the inspector, as a person can evaluate 60% and an other inspector 80% for the same observed area. This leads to complications when performing coverage mapping.

2 - Inspection of coverage on hard materials that leave really small and shallow dimples. I remember that a Boeing specifications give guidelines for use of the saturation time of the Almen strip and a correlation with the area being peened to determine the exposure time of the part. As concerned as I am about not confusing the Almen saturation time with the required exposure time, I think some guidelines should be provided for coverage evaluation on hard materials. I have however no idea at the moment of what those guidelines could be.

Anybody every used that correlation method for high hardness / high strength materials?

#455 03/11/08 08:05 PM
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Paragraph 3.2.1.2 of AMS2430 appears to NOT allow the use of manual peening for areas that cannot be reached by an auto peener. Is this the case? Manual peening is not allowed per this spec? What about any areas that you cannot reach with automatic machines?

#456 03/11/08 09:40 PM
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Wayne,
I agree that paragraph 3.2.1.2 does not allow manual peening. This intention has been discussed and affirmed at several AMEC meetings. For jobs in which areas that cannot be reached by automatic machines should be discussed with purchaser. If the part is new to peening, i.e. oem, then part owner should be describing the peening treatement. If part is being re-peened then you probably must assume 1) it was peened properly initially and 2) re-peening should duplicate the initial efforts.

#457 03/12/08 01:20 PM
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Jack,
We are concerned about the manual peening not being allowed in the new AMS2430. In paragraph 6.5 of AMS-S-13165, "Additional Peening", there appears to be an allowance for manual peening. The last sentence, "Use of special nozzle equipment" is how we get there. Why is it not being allowed in the new procedure? What happens to parts that we have (in the past) manually peened (AMS-S-13165) and then the same parts need peening per AMS2430? It sounds like this issue is going to be bigger than we think, industry wide that is.

#458 03/12/08 01:48 PM
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Walter Offline OP
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Wayne,

Is your question in response to AMS-S-13165 being superseded by AMS-2430?

If so, I have to ask where does AMS-S-16165 say manual peening is allowed?

AMS-S-13165
Section 3.2 Equipment

3.2.1 Automatic shot peening:
The machine used for shot peening shall provide means for propelling shot by air pressure or centrifugal force against the work, and mechanical means for moving the work through the shot stream or moving the shot stream through the work in either translation or rotation, or both, as required. The machine shall be capable of reproducing consistently the shot peening intensities required. Except of wet glass bead peening (see 3.3.9), the equipment shall continuously remove broken or defective shot so that this shot will not be used for peening.

3.2.2 Computer-controlled shot peening:
When specified in the contract or purchase order (see 6.2 and 6.8), the machine used for shot peening shall be as in 3.2.1 and also shall be equipped with computer aided monitoring equipment. This equipment shall continuously monitor critical process parameters through interaction with a sensing system. The media shall be metered to each nozzle and wheel with the desired shot flow. Process parameters shall be as specified by the procuring activity (see 6.9. The machine shall be stopped immediately and corrective action shall be taken when any of the established process limits is violated. The electronic system used for monitoring and controlling shot peening shall include a data recording device which will mark (plot) process interruptions or inconsistencies, and shall be maintained for the purpose of providing a hard copy record.

There is no mention of manual equipment in this section.


3.3.7 Coverage:
Areas of parts shot peened in compliance with design requirements shall be peened to complete visual coverage (see 4.4.1 and 6.11). When a surface on which peening is required is obstructed and it is impossible to obtain complete visual coverage by direct impact, coverage by reflected shot is allowed. Full coverage will not be required if the part is peened only for forming or straightening. Critical applications shall be as specified by the procuring activity (see 4.2 and 6.11).

6.4 Special peening procedure:

Where a special procedure is required, applicable drawings or a contract will designate such critical areas (see 4.2).

This is where you would have to obtain approval from your customer to permit manual peening.

6.5 Additional peening:

Shielded or partially shielded areas, walls of deep recesses, or other areas less accessible to the maximum effect of the blast stream will receive less peening as to intensity and coverage than more exposed or more favorably oriented areas, and may therefore require additional peening or repositioning of the part to achieve correct peening in these areas. Use of special nozzle equipment or employment of deflector peening operations may be useful in diminishing the amount of additional peening.

This is the big one. Time and time again people at SAE AMEC meeting state they need manual peening to get to hard to reach areas and AMS-2430 does not address it. I’m not sure why but many people feel that AMS-S-13165 permits it. There is nothing in this specification that even references manual peening. I agree that there are some OEM specifications that allow it but not many.

I'm sure this is why there is no reference to manual peening in AMS-2430.

#459 03/12/08 02:59 PM
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Walter,
I guess that it is all in the interpretation of 6.5 "special nozzle equipment". Just like most specifications there is alot of room for interpretation in the AMS-S-13165. There is also no mention of manual peening not being allowed. We employ quite a bit of manual peening along with automatic peening. There are a lot of various configurations that we would not be able to peen without utilizing the manual peener. In those cases the new AMS2430 would require notifying the customer in each case and having them approve the techniques employed, I assume?

#460 03/12/08 04:00 PM
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Walter Offline OP
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Wayne,

You are correct when you state "there is a lot of room for interpretation in the AMS-S-13165".

I have also heard the argument at SAE AMEC meetings that there is no mention of manual peening not being allowed.

I don't mean to be rude but this logic is flawed and dangerous. At what point would the specification stop listing things that were not permitted? Example: The specification does not say that I can't use grit to peen the part. But we all know you would never do such a thing. The intent of the specifation is to tell the user what must be used it is not a suggestion.

6.5 "special nozzle equipment"
It is supposed to mean a custom nozzle specially designed to peen the hard to reach area. i.e. a deflector tip nozzle. If a part can be peened manually it certainly can be peened automatically, it’s just a matter of having the proper equipment.

We also use manual peening where it is permitted by specification, drawing or contract. Normally we use it on local area re-worked parts but not always.

You wrote "In those cases the new AMS2430 would require notifying the customer in each case and having them approve the techniques employed, I assume?"

That's exactly right. However, a much simpler way of doing it would be to write one Quality Assurance Procedure / Work Instruction that states you take exception to section xxxx in specification xxx and will be using manual peening in difficult to reach areas in lieu of automated peening. Then have each of your customers sign the document on an as needed basis.


You should look into becoming an AMEC member. I belive you can get started by going to this link.
http://www.sae.org/standardsdev/participationReq.htm Or Contact Jack the host of this site.

The more users we have involved the better the Shot Peening Industy will be.

Hope that helps,

-Walter Beach
Peening Technologies
Hydro Honing

#461 03/12/08 05:05 PM
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Walter,
Thanks for all of the information and replies. I do not take anything that you have to say as rude but, manual peening is a peening operation and utilizes nozzles. I think that a lot of folks are interpreting it the same way. Manual peening being allowed that is. I have never even considered (until this forum) that manual peening was not allowed. If a specification is "supposed to mean" something specific one would think that it would be specific about that issue. Thanks for the idea of a Quality Procedure/Work Instruction, that is probably the quickest, easiest and cleanest way to accomplish this.

Why would controlled, documented manual peening (in inaccessable areas) not be allowed in the first place?

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