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

[2muchcoffee]

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?

 

[swall]

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.

 

[micalbrch]

You wrote that ASTM A228 is the replacement for QQ-W-470 but is QQ-W-470 withdrawn and officially no longer valid?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.

 

[2muchcoffee]

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.

 

[TVP]

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".

 

[2muchcoffee]

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!

 

[2muchcoffee]

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.

 

[EdStainless]

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

 

[IRstuff]

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

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[USAeng]

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

 

[2muchcoffee]

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>

 

[swall]

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

 

[2muchcoffee]

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...

 

[IRstuff]

Hmmm. According to the ASSIST website:

https://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=51029

QQ-W-470 was cancelled almost 26 yr ago.

So, was your material ever procured to UNS G-10800 requirements? If so, and they haven't had any problems, you might want to point that out.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[2muchcoffee]

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.

 

[1gibson]

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.

 

[2muchcoffee]

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)".

 

[salmon2]

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.

 

[2muchcoffee]

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.

 

[IRstuff]

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

FAQ731-376
Chinese prisoner wins Nobel Peace Prize