Calling out standard bolts on drawings & bolt certs

[bc1080]

In our work we usually (pretty much always) deal with NAS fasteners and so we are use to having a very specific fastener code to place on drawing EPLs to allow the shop to order the exact fastener we need from any number of industry vendors. We are now designing a piece of tooling and are wanting to use standard Grade 8 bolts. We are struggling to find any part numbers or standardized "codes" to place in the parts list to indicate a specific fastener. I know the bolts (for example) are SAE J429 Grade 8 bolts (which use dimensions from ASME B18.2.1). I have tried to describe the bolt like follows:
SAE J429 GR8, 1.0-12X3.0
But the shop says this is not specific enough for them to order a fastener. The only thing left I can think to do is narrow it down to a vendor and use their unique product ID/SKU number on the EPL, but this removes flexibility for the shop to be able to use other vendors if they are out of stock or find a lower price (without having to rev the drawing to change the code or approve an alternate). I am wonder what other engineers/fields do to call out "normal"/Grade 8 bolts that do not have a standardized coding system similar to NAS.

In a related question; we do not need the traceability of the NAS bolts, but are not sure if there are options where we can get some intermediate forms of certification (lot certs, etc) that satisfy that the fasteners meet at least basic material and strength properties and that they are not forgeries. I was around at a past job when this issues was dealt with and solved, but I was not directly involved so I may not be remembering the terminology or describing it 100% accurately. Does anyone know what I am trying to describe in terms of something between a NAS bolt and grabbing something from a bulk bin at a hardware store? We are trying to not get pushed into two extremes where it is either full certs or no certs at all.

 

[dik]

Did you check the Portland Bolt site... lots of good info.

Dik

 

[SwinnyGG]

If you want mid-level traceability with lot numbers, you're going to have to lock yourself in to a single supplier.

I occasionally have this problem as well, and have found that different fastener manufacturers have traceability schemes different enough that if you switch suppliers you lose the traceability you were going for.

In short, if you want even a modicum of traceability, just pick a manufacturer and specify their part number.

 

[SnTMan]

bc1080, have you considered a spec bolt such as ASTM /ASME A-193? You can also usually get a Certificate of Conformance from the supplier, stating it is what it is supposed to be.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[hydtools]

What does the shop say they require for full specificity?

Ted

 

[SnTMan]

Well, I guess J429 IS a spec bolt. Don't know what else your shop would want, maybe head style?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[SnTMan]

Best thing is to get the shop to write down exactly what they want to see, and give it to you. You date it, and put it in your file. You prepare the drawing as the shop asked, and when somebody kicks about it, you pull out your note...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[bc1080]

I appreciate the responses so far. I have run across Portland bolt in the past, but now looking their site is again very useful. I might have them write up a quote and see what they can do in terms of the certs.

I hadn't checked into A-193 bolts, but they do look to have a shade less tensile strength than Grade 8 and we are very tight on margin at this joint. We could also only use the B7 variety because we are only permitted to use certain grades of stainless steels.

In light of not having a common certification system or standards to reference, we would probably be OK with going to a single supplier (and approving deviations as required). It appears the shop just wants to place an order based on specific numbers/product codes and not have to do any thinking when placing the order. They want something that lays out every possible dimensions/option/coating/etc. to the T so they can give us exactly what we think we are getting. They want nothing to do with selecting the fastener or having any options to chose from. The cert thing is completely self-imposed by engineering that we want to make sure we are not buying fakes or something and that we have some proof the bolts are what they say they are material/strength wise.
I'm trying to get them to document their needs as we speak. They currently have one of their planners submitting RFQs to see what they could find so they could feed back the info to us (but they are just looking at local suppliers as far as I know).

 

[MintJulep]

J429 specifies exactly how to completely and unambiguously specify for purchase.

 

[CWB1]

For each industry standard (NAS, SAE, ASTM, etc) you need a company standard specifying a revision level. Either via those company standards or a separate print you can then track your company's part numbers for each specific fastener to include size, grade, coatings, etc.

 

[SnTMan]

It appears the shop just wants to place an order based on specific numbers/product codes and not have to do any thinking when placing the order. They want something that lays out every possible dimensions/option/coating/etc. to the T so they can give us exactly what we think we are getting.They want nothing to do with selecting the fastener or having any options to chose from.

People in H3ll want ice water

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Sparweb]

...but they do look to have a shade less tensile strength than Grade 8 and we are very tight on margin at this joint...

Wait a second... you may save money, but are you increasing risk by NOT using the NAS compliant bolts?

...It appears the shop just wants to place an order based on specific numbers/product codes and not have to do any thinking when placing the order...

Does that mean they also won't inspect samples from the lot they receive, or examine the paperwork that's included? Then for peace of mind...

Myself, I've had to accept that the purchaser probably doesn't know anything about the parts on the drawing. They're just names and numbers to some of them. We have some clever purchasers and planners who know what these things are, but we also have some who don't.

STF

 

[CWB1]

Does that mean they also won't inspect samples from the lot they receive

How would they begin to approach that? "SAE J429 GR8, 1.0-12X3.0" calls out one of multiple fasteners somewhere described in one of multiple standards.

 

[EdStainless]

If you read J429 or A193 (or any other good bolt spec) it will list the ordering requirements.
That is all that is needed to get the correct item.
That is why that "laundry list" is there.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[Screwman1]

The SAE J429 gives total control over the mechanicals and if you want some type of a hex head, then you can call out dimensions to ASME B18.2.1, along with which head style you want. That will give you standards for both mechanical and dimensional characteristics. If you want some other head design you will need to find the appropriate ASME head standard and specify it.
As far as lot control, that will depend on your vendor. These will probably be off the shelf parts and so you will need to find a vendor who will provide you with material and HT certs, along with a COC. For commercial, standard parts, that is going to be about the best that you can hope for unless your volume is great enough to get a production run going and then you can get whatever level of certs that you want(for a cost).

 

[bc1080]

Wait a second... you may save money, but are you increasing risk by NOT using the NAS compliant bolts?

It's money and availability on the fasteners we are worried about. We have large safety factors and a very conservative, simplified analysis approach (analysis doesn't have time to sharpen the pencils due to a short schedule), so I have to keep around 150ksi ultimate to make the bolt calcs positive. In reality I am far from worried about the capability of the bolts since the loads we are using are ridiculously high compared to actual design loads. The critical case is a G-load factor from road transport (basically an accident load), and we are only moving it one time anyway and I'm sure we'd just build a new one if anything questionable happened.

Does that mean they also won't inspect samples from the lot they receive, or examine the paperwork that's included? Then for peace of mind...

They will do CVT testing on the delivered lot and test samples (since we are telling them to). I am sure they would gladly not do it to save themselves effort. The included paperwork is one thing I am trying to determine that we make sure we get, so we have something to examine.

It sounds like if we order to the J429, then that means it should come with certain items (I'm reviewing the standard again as we speak), and depending on the vendor they may have additional paperwork that we can review as well and we just need to verify and set this up front as a requirement. It appears to be a "lessons learned" thing that the last time the shop bought non-NAS bolts they ran down to the local fastener store and got some bolt that were advertised to meet some standard and didn't get any paperwork with them, so we couldn't verify the end item. The question is more making sure we get the paperwork to validate the bolts conform to J429 and we will be good to go.

 

[tbuelna]

If you want to control procurement of a "standard" commercial fastener that is permitted to be purchased from several different vendors using their existing part numbers, then you might consider creating a Vendor Item Control Drawing. The Vendor Item Control Drawing defines a single internal part number you specify on your engineering drawings/BOMs, and also a table of acceptable vendor part numbers that can be used to procure the item.

Suppliers like McMaster-Carr will provide fasteners in sealed boxes along with certs if you want.

 

[bc1080]

Appreciate the responses! I got tied up and just getting back to the issue. I think we definitely have a path forward now and better understanding. If there are any issues with our planning to call out a specific vendor/bolt on the drawing (essentially a vendor's SKU number), we will likely use a vendor item control drawing.

Ironically, in my opinion calling out a single fastener like this it is even MORE restricting to them than a NAS-type fastener (should still be a lot cheaper though I hope), but it does remove all ambiguity.

 

[CWB1]

The Vendor Item Control Drawing defines a single internal part number you specify on your engineering drawings/BOMs, and also a table of acceptable vendor part numbersthat can be used to procure the item.

Its generally considered bad practice and I would caution against adding supplier p/ns to any print or internal system, you want the suppliers making, purchasing ordering, and quality teams accepting parts to YOUR spec, not theirs which is guaranteed to change over time independent of you.

 

[Tunalover]

ASME made an attempt at issuing a part numbering system for screws but it was so unwieldy that no one used it. The part nos were VERY long and difficult to nail down. IMO it was too much to ask for sales people to like and use that system. I don't know if the standard is still being issued. It was long ago.



Tunalover
Electro-Mechanical Product Development
UMD 1984
UCF 1993