Tolerances for cold rolled, hot rolled, DOM tubing

[apestate]

I think this may be more of an ASTM/SAE/ASM standard question than anything ISO, but I can relate it to our QMS here so:

We are a production hardware shop cutting parts out of 12L13, 1144, 1040, 316 stainless steel, etc. I have a detailed tolerance list from EMJ (distributor) and it references all the various AMS/SAE/ASTM, MIL standards for different material configurations.

What should I use for tolerances on cold rolled, hot rolled, DOM tubing, aluminum rod / hex / square etc, etc. Can I use this EMJ technical reference? Should I look into purchasing the standards?

[Graeme]

Question: is EMJ your supplier, or your customer, or just someone else who happens to list technical data for the steel you use?

Graeme

[CarolX]

What tolerancing are you looking for...

physical size or chemical composition?

For chemical composition I would take the time to look up the standard. These issues can be critical to the end use of the product.

Carol

[apestate]

EMJ is a supplier who has compiled a list of tolerances of both chemical and dimensional characteristics of the metal they sell in their technical resource. They disclaim that it is complete or up to date.

They supply the material of, for example 1144, with a material certification from the mill. The material certification is kept on file for traceability but we do not review it for chemical composition.

We check the material dimensionally to make sure we can actually run it in the machines, for condition, quantity, etc. This is all.

Do you see a need to review the material certifications for chemical composition standards?

Would it be OK to go by the EMJ list of dimensional tolerances for our incoming inspection?

[CarolX]

I can't really answer that question...because I don't know your end product.


Nowadays, I work in a commercial sheet metal fab shop. We make all sorts of sheet metal parts for cabinets, furniture, computeres, etc. And if the skid is marked with what we ordered...great, we are good to go.

In a past life I worked for an aircraft parts manufacture. We required traceable copies of mill test reports, performed mill sampling on a quartly basis, and used the ASTM/ASME/MIL specs to defined our chemical composition requirements and tolerances.

So I guess it is up to you to define your needs and requirements, cuz it depends on what your making.

Carol

[SteelMaiden]

As a past employee in a division that supplied EMJ with bar stock, you probably can use their tolerances and chemistry spec limits. But, if you need to be dead certain about those tolerances/chem specs for your customers, I would probably go ahead and buy the ASTM books that have the chem and size tolerances. In my experience, chemistry and size tolerances haven't changed in the 27 years I've been in the steel industry so once you had the relevant specs, you'd be good to go. There is a site(s) where you can purchase ASTM specs individually so you wouldn't have to get the entire set. One of the sites is Global Engineering Documents at http://global.ihs.com/

[apestate]

I believe that the specs that are relevant are included in this EMJ tech reference. I agree that the specs have not changed in 25 years and they are all listed in this book as I expect them to be.

We make parts for filtration components and devices and a broad variety of other various job shop / screw machine shop type work. We don't really have a need or capability to verify or audit material composition.

I believe using the tech resource from this distributor would be vastly sufficient for our work. The material certification documents are enough for our customers and historically there has never been a need for verifying material chemistry.

I guess I'll treat the resource guide as a controlled document and be on my merry way with this one.

SteelMaiden, would I ever be shipped out of tolerance material with an accompanying material certification sheet?

[SteelMaiden]

Originally Posted by atetsade

SteelMaiden, would I ever be shipped out of tolerance material with an accompanying material certification sheet?

UMMMM, never say never...I would have to say that I seriously doubt that you'd have a chemistry problem and as long as your size tolerances are no tighter than EMJ's (they typically order to standard industry tolerance) you'll probably be fine. Unfortunately, I cannot guarantee that every facility operates at the same Cp and Cpk values that ours did. We worked long and hard to implement a very thorough SPC program and were pretty much running at 3.6 or higher for both Cp and Cpk for sizes.