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Material specification vs. material grade - how do they relate?
15

Material specification vs. material grade - how do they relate?

Material specification vs. material grade - how do they relate?

(OP)
We are a spring manufacturer.  We made springs to a customer's drawing but they are rejecting them.  Their complaint is that we used the wrong material.  Their drawing calls out "Music wire per QQ-W-470, spring temper, UNS G-10800, .0220 ± .0004 dia."

We ordered - and used - music wire per ASTM A228 (replacement for QQ-W-470) which defines the material's chemical composition.  But as pointed out by our customer, the chemical composition of UNS G-10800 is different from the chemical composition prescribed in ASTM A228, as follows:

ASTM A228    
Carbon: 0.70 - 1.00%
Manganese: 0.20 - 0.70%
Phosphorous, max: 0.025%
Sulfur, max: 0.03%
Silicon: 0.10 - 0.30%
    
UNS G-10800    
Carbon: 0.75 - 0.88%
Manganese: 0.60 - 0.90%
Phosphorous, max: 0.04%
Sulfur, max: 0.05%
Silicon    : "as required"

I'm trying to understand what, to me, is an apparent contradiction.  That is, how can they specify music wire to material spec QQ-W-470 (now ASTM A228) that defines the material's chemical composition limits, while simultaneously specifying it to a UNS category that sets contradictory chemical composition limits?

I'm missing a critical element of understanding here and I don't know what it is, or who to go to for a clear explanation, or even how to frame a relevant question.

Any ideas or help?
 

RE: Material specification vs. material grade - how do they relate?

Essentially (and perhaps unintentionally), your customer is specifying a very restricted chemical composition (1080 wire) within the limits of the ASTM A228 spec. Perhaps they do not understand this and the issue needs to be clarified so that the drawing can be changed to reflect what spring material is available that will work for the application. I just went through this with snap rings supplied to a large Ag Eqpt Mfgr.

RE: Material specification vs. material grade - how do they relate?

2
You wrote that ASTM A228 is the replacement for QQ-W-470 but is QQ-W-470 withdrawn and officially no longer valid? If not, you have a problem. Standards are not laws and even if standards are replaced, customer and vendor can still agree upon them.

Do you have a material certificate for your ASTM A228 material? Looking at the above chemical composition comparison it is likely that your material falls within both ranges.

RE: Material specification vs. material grade - how do they relate?

(OP)
Thanks swall,

So far they are simply asking why we didn't make the springs out of UNS G-10800 material.  At this point I need to open a dialogue with them to discover the scope of their complaint and discuss design requirements.  I'm trying to gain insight and knowledge beforehand to be able to participate in an informed discussion.

I have a feeling they will change the material callout on the drawing, but in whose favor it will be remains to be seen.

I'd be interested to hear how your similar situation got resolved.

RE: Material specification vs. material grade - how do they relate?

I agree with swall.  Your customer, for whatever reason, is specifying a restricted composition within the ASTM standard.  It is almost a certainty that they do not really need this, and that they do not understand the implications of using "ASTM A228" vs. their "spec".

RE: Material specification vs. material grade - how do they relate?

(OP)
Hi micalbrch,

Yes, QQ-W-470 is cancelled, in 1985. The cancellation notice refers future procurement to ASTM A228.  That much is clear.

And yes, we do have the material cert.  While it's possible to produce material that conforms to chemical composition requirements of both ASTM A228 and UNS G-10800, the overlap range is pretty narrow and our material cert clearly shows the manganese percentage is too low to meet UNS G-10800. Dang!

RE: Material specification vs. material grade - how do they relate?

(OP)
Hi TVP,

My dilemma is that the UNS G-10800 grade of material consists of a range of chemicals that fall outside the ASTM A228 standard, not within.  

To look at it another way, the drawing material callout consists of 2 requirements (ASTM A228 and UNS G-10800), each of which contradicts the other.  This is sort of like a zen koan, 'what is the sound of one hand clapping?' in that it makes no sense to me.

Thus my continuing confusion. ponder

RE: Material specification vs. material grade - how do they relate?

2
Some people mistakenly use spec wrong, such as calling out 1080 to the properties of A228.  You can't comply with just part of a spec, it is all or nothing.
Often people do the sort of thing that your customer has but there is enough overlap between the two chemistry that you can actually make the product.
Also sounds like you missed a spec review up front.  You should not have taken the order with this requirement.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: Material specification vs. material grade - how do they relate?

Nonetheless, even though the customer may have had conflicting requirements, your drawing had those requirements written down, and while you went with the standard, you ignored the specific material callout.  Your people should have done a due diligence and asked the customer what he really wanted, given that the requirements are in conflict.

TTFN

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RE: Material specification vs. material grade - how do they relate?

are they saying general requirements to the QQ spec and heat treat to the UNS spec?  

RE: Material specification vs. material grade - how do they relate?

(OP)
IRstuff and EdStainless,

You are both correct, we did miss the discrepancy during contract review and we should have caught it then (due diligence).  But we didn't.  Now here's the kicker...we have been making this same part for the same customer for over 14 years.  Neither of us have 'caught' this until now.

Things change. <sigh>

RE: Material specification vs. material grade - how do they relate?

No. The UNS is just a callout for steel of 1080 chemistry. It does not reference mechanical properties or heat treatment.

RE: Material specification vs. material grade - how do they relate?

(OP)
Hi USAeng,

No, they are specifying the raw material to the Fed spec and the UNS grade simultaneously (all in one breath, so to speak).

It's not the mechanical properties that are in question, it's the chemical composition.

Very frustrating...

RE: Material specification vs. material grade - how do they relate?

(OP)
IRstuff,

Yeah, this is an old drawing.  Its initial release pre-dates the cancellation of QQ-W-470, so the QQ-W-470 spec was valid at the time the drawing was initially released.  

So now I wonder, am I dealing with an issue where the material callout was valid at the time the drawing was released, but which is now invalid due to changes in the interim?

And no, we never produced using UNS G-10800.  There is also the fact that there has never been a reported failure.  I will stop short of reminding them that they also missed the material discrepancy for the past 14 years.

RE: Material specification vs. material grade - how do they relate?

2
14 years and this is the first time rejected... WHO is rejecting? New inspector, new QA/QC guy? Ask the engineers to change the drawing and give the revision to the guy raising the flag.

My opinion - it is not proper use of the specs, but if the material requirements DO overlap, then nothing is contradictory in the strictest sense of the word.

If you ask for a part to be red in one place and blue in another, that is a contradition. Purple would not be acceptable. Red with blue stripes would not be acceptable.

If you ask for a rectangle in one place and a square in the other, you're getting a square which also happens to fit the description of a rectangle. Not contradictory.

"What is the sound of one hand clapping?" Not as loud as 2 hands clapping, but it is still audible. Depends how many fingers hit your palm.

RE: Material specification vs. material grade - how do they relate?

(OP)
Hi 1gibson,

Customer is a huge conglomerate going through a corporate-level restructuring and improvement effort.  Our specific customer is a former small subsidiary that is now under a larger umbrella and being absorbed into this new corporate culture, so they are scrutinizing everything.

Your illustration points are well taken (colors, shapes).  A question I have, though, is how do we order material?  So far our material suppliers are saying "one (red) or the other (blue), not both (red and blue)".

RE: Material specification vs. material grade - how do they relate?

2
As others pointed out there are overlaps: carbon of 1080 is witthin a228; Mn is main concern but if the Mn of 1080 falls to lower end which is usually the case as it is expensive it is again in the range of a228...

Or if your volume is big enough, write your own spec and order the min tonnage from mills.

I feel you should be able to find a solution to the current issue given your 14 yes of relation and no field failure. Technically it should be a OR between a228 and 1080.

RE: Material specification vs. material grade - how do they relate?

(OP)
Hi salmon2, good points.  If we went back through each material lot and reviewed the certs for chemistry, we may find one or two heats that met both.  As you point out, the Mn has a narrow range and it usually is at or near nominal when we order music wire to ASTM A228, which is well below the minimum for UNS G-10800.  Rats!

I think this will end OK, with customer changing material callout on the drawing.  My greater concern is towards our relationship, and how or if it will change.

RE: Material specification vs. material grade - how do they relate?

Depends on the company, I suppose.  However, most companies would probably increase the scrutiny they apply to your company and your products.  As a minimum, then, your company should immediately do a complete review of product and its processes to ensure that EVERYTHING is fully compliant.  You can then present the results of your investigation to demonstrate your proactive approach to a dropped ball situation.

TTFN

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RE: Material specification vs. material grade - how do they relate?

(OP)
Yep!  We're doing that too.  This job was the latest from an annual multi-ship PO that was reviewed and quoted last year.  Since then we have tightened up our review process due to other in-house audit findings, and are much better at finding, questioning and documenting this sort of thing.  We know we have areas that need improvement and are doing so.  Customer also knows this.  As for scrutiny, they have already  ramped up their scrutiny on every level due to new higher-level corporate program improvement.  And you know what flows downhill, right? winky smile


 

RE: Material specification vs. material grade - how do they relate?

Just want to comment that there really is nothing contradictory in the drawing callout.  It is possible that the material will meet both requirements, and this is probably what the "new guard" is expecting you to provide.  While is it possible that the application does not actually require the restricted Mn content of the UNS specification, as a supplier, you do not know this and it would be wrong for you to just assume they don't understand what they have specified.  Perhaps they have knowledge that the lower Mn contents do not perform as well in their applications.

As far as ordering material goes, you can say "Material per ASTM 228 excpet chemistry must be per UNS G-10800".  

Of course, it could be possible that things have gotten confused over the years.  Do you have access to the QQ-W-470 specification that was active when the original drawing was produced?  If you can get a copy, it may be useful to see if the chemical composition listed in the old specification matches what is now in the current ASTM A228.  Is it possible that the old QQ-W-470 spec was loose on chemical composition and that the UNS callout was needed to insure the correct material was used?  Obviously, when the QQ-W-470 was discontinued the drawing should have been revised to reflect the active specifications, but that didn't happen.  All you can do now is to try to get the customer to use current specifications.

Regardless, you will have to negotiate with your customer to resolve this situation to your customer's satisfaction.  

rp

 

RE: Material specification vs. material grade - how do they relate?

(OP)
Yes, I do have a copy of the original QQ-W-470 spec.  The ASSIST website is an invaluable resource for MIL specs and FED specs, and it's all FREE! smile

Interestingly, the chemistry is very slightly different between the old QQ-W-470 spec and the current ASTM A228 spec, most noticeably for Manganese (old was 0.20% - 0.60%, new is 0.20% - 0.70%).  So with the old QQ-W-470 spec there was no Manganese overlap to the UNS chemistry (which is Mn 0.060% - 0.90%), but the newer ASTM spec provides wiggle room (some overlap) for Mn.

I was hoping there might be someone in this forum with mill experience to explain how the two material callouts relate to each other (QQ-W-470 vs. UNS G-10800), and what would our PO need to look like in order to receive compliant material?  So far our material suppliers have not provided such expertise.

RE: Material specification vs. material grade - how do they relate?

I will suggest to contact your customer to confirm that they really need QQ-W-470 plus 1080 because the 0.6~0.7 Mn is a bit tight and it can possbily drive up your price to get raw material.

But on the other hand, a range like 0.6~0.9 of 1080 is not the range that steel mills absolutly need to produce 1080. If they pay attention, they can control Mn in that range all day long. I had experience to order mill runs for many years and I can say that the variance of Mn is small within a batch of different heats.

1080 is a plain carbon steel and the only alloying element is Mn. If the steel mill is BOF, they can control it easier than a EAF mill as they have to literally add in Mn to a level versus EAF that they have to balance their different scraps to get the tight range for Mn. So possibly you have to pay a surcharge if you insist on 0.6~0.7 of Mn.

RE: Material specification vs. material grade - how do they relate?

(OP)
I've just learned that our customer has submitted an ECR to change the drawing material callout to ASTM A228 and remove the UNS G-10800 designation.  All of a sudden it's a non-issue, nor our fault.

Hmmm...

Of course, we still have process issues to remediate, but those are already pretty much resolved.  In the end, everyone is better and smarter.

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