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?

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

Graeme

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

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?

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

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/

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, 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.

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.
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?I think Eric is putting the horse before the cart, here.
First of all, the tolerances listed in a metal distributor's catalog are merely the repeated compilation of various charts published by various metal producers regarding the "as-produced" tolerances of the material as it comes from the mill. In addition, service centers may straighten coil stock and cut bars, sheets, coils, rods, and tubing to more manageable size for machine shops and fabricators.

These "commercial" tolerances are compiled in a much more authoritative and widely distributed reference work, Machinery's Handbook (http://www.industrialpress.com/mh.htm) along with lots of other useful information. Every machine shop and job shop should have an up-to-date edition of this useful reference work.

Next, the issue is the USE Eric's shop will make of the tolerances. Is it to use as an objective Standard for accepting incoming material? Is it to propose as a tolerance standard for work pieces made for a customer?

If for incoming inspection, any chart of sizes and tolerances may be formally adopted into an organization's incoming acceptance Procedure.

If it is for a basis of negotiation with customers for finished work, both sides need to understand the origin and common use of so-called "commercial tolerances."

Raw material mills necessarily produce material to cater to a wide variety of users. Hence, some user organizations producing products on Swiss screw machines to tolerances as tight as fifty millionths of an inch sometimes find it economically feasible to run mill-produced bar stock through a Brown & Sharpe or Acme Gridley screw machine to a tolerance of -0.0000/+0.0010 inches before running it through the Swiss. The savings on tooling wear and being able to increase speeds and feeds in the Swiss more than make up for the cost of just turning the stock to size in the Brownie. Compare that to commercial tolerance for "turned and polished" bars at +/- 0.003 inches for carbon steel (12L14) of less than 1-1/2 inches in diameter.

Bottom line:

For incoming inspection, any chart of tolerances will do.
For outgoing inspection in a job shop, the customer's requirements for tolerances take precedence.

I briefly looked through Machinery's Handbook this morning but I was unable to find tolerances for rolled bar stock. I will check again, something faintly reminded me to look for straightness tolerances in the screw machine section.

If anyone is still on the subject, what is "rough cut" material and how common is it in the supply? We received 2-5/8" 316L stainless steel in "rough cut" condition without being notified of any difference. 2.653 instead of 2.625. The round bar looks heavy turned.

of course, that's the closest size of 316L round available through our normal suppliers. I think I'll look into some name brands.

if Machinery's Handbook has the specs I will use them, if not, I'm going to use the tech resource from the distribution house, it's probably just what we need.

I briefly looked through Machinery's Handbook this morning but I was unable to find tolerances for rolled bar stock. I will check again, something faintly reminded me to look for straightness tolerances in the screw machine section.

If anyone is still on the subject, what is "rough cut" material and how common is it in the supply? We received 2-5/8" 316L stainless steel in "rough cut" condition without being notified of any difference. 2.653 instead of 2.625. The round bar looks heavy turned.

of course, that's the closest size of 316L round available through our normal suppliers. I think I'll look into some name brands.

if Machinery's Handbook has the specs I will use them, if not, I'm going to use the tech resource from the distribution house, it's probably just what we need.You are probably correct, Eric.
The tolerances on incoming stock seems to be your primary concern. Your organization is the best judge of what tolerances meet your need, depending on the kind of machining you will do and the output required by your customers.

:topic: For what it's worth - my machinists raved about the consistency of Carpenter brand 316L from lot to lot and from size to size, reducing tool chatter and undue wear. When we ran independent labs on the chemical and physical properties, they had a 100% record of conformance. These factors, among others, convinced us to pay more for Carpenter brand than other available products, especially for stainless steel alloys.

:topic: :topic: I was stunned to note some major differences between the Table of Contents and Index for the 26th edition of Machinery's Handbook (listed on their website) compared to my well-worn 23rd edition. Whereas my 23rd edition discusses and lists the tolerances for mill products (by referring to AISI), the 26th edition does not.

When in doubt, go to the industry standard. Referring to the American Iron & Steel Institute (http://www.steel.org/learning/glossary/t.htm) (emphasis is mine)

Tolerances
A customer's specifications can refer to dimensions or to the chemical properties of steel ordered. The tolerance measures the allowable difference in product specifications between what a customer orders and what the steel company delivers. There is no standard tolerance because each customer maintains its own variance objective. Tolerances are given as the specification, plus or minus an error factor; the smaller the range, the higher the cost.