How materials should be identified on prints?
How materials should be identified on prints?
(OP)
When creating a print for a finished good that will be produced in-house, what's the best way to identify the required materials on the print.
For example, a company purchases and inventories 5/8" diameter x 16' long bars of CR 1018 steel under an internally created part number AA123 per the companies ERP system. When this material is required to make one of the companies products, should the material be called out on prints as 5/8" diameter x 16' long bars of CR 1018 or should it be identified as AA123?
What is good engineering practice? I've looked into the ASME design standards but I haven't found anything that address how materials and components should be identified on prints, i.e. by industry standard or by the internally created part numbers companies use to purchase their materials.
For example, a company purchases and inventories 5/8" diameter x 16' long bars of CR 1018 steel under an internally created part number AA123 per the companies ERP system. When this material is required to make one of the companies products, should the material be called out on prints as 5/8" diameter x 16' long bars of CR 1018 or should it be identified as AA123?
What is good engineering practice? I've looked into the ASME design standards but I haven't found anything that address how materials and components should be identified on prints, i.e. by industry standard or by the internally created part numbers companies use to purchase their materials.





RE: How materials should be identified on prints?
I'd go further than this, unless you are keeping the 'stock' dimensions on the finished part you should only call out the grade. This allows them the freedome to machine the parts from different size stock if required.
Many government contracts, and possibly some of their specs, require that the grade be given along with the specific material spec & in many cases an approved alternative also be listed.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
RE: How materials should be identified on prints?
For example, lets say you are making several different parts with this material. If you reference AA123 and then change to HR 1018 you only have to change the base print not multiples.
ISZ
RE: How materials should be identified on prints?
Kyle Chandler
www.chiefengineering.net
RE: How materials should be identified on prints?
Use only the material spec and/or an internal code for that spec. Don't use the number assigned for the raw material as purchased and stocked.
Ted
RE: How materials should be identified on prints?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: How materials should be identified on prints?
The various departments where I work, have different policies regarding numbers used on BOMs. I watched one of our electrical engineers curse a parts list with nothing but stock codes on it. The stock code system was inaccessible to him, so he could make no sense of the components of the PCB he was trying to figure out.
I have been told by one of our manufacturing guys that he would prefer BOMs with nothing but stock codes because that would allow us to change part numbers without revising all of our BOMs. He was assuming that we would have a good specification control system in place, which would have solved the engineer's problems, noted above. I was comfortable with his idea because I figure I could set up SolidWorks to create several types of BOMs, depending on the end user.
I would say that your ERP stock code is perfectly functional if there is a good reference explaining it. If the number is buried in ERP's database, inaccessible to engineering, you are in trouble.
If you want something to be 5/8" in size, you should apply the dimension 5/8" on your drawing, with your required tolerance. The material is CR 1018. Who cares what the raw material was?
JHG
RE: How materials should be identified on prints?
RE: How materials should be identified on prints?
RE: How materials should be identified on prints?
but from an engineering perspective, you'd want to specify bar stock 2" OD, finished ...
RE: How materials should be identified on prints?
If one material is purchased per pound but used in linear units(ft, inches, mm etc) then someone will need to do a conversion to keep inventories near correct. It seems to work best if consumption is listed in the units your operator will most likely use.
After a number of years of taking inventory, checking prints, and troubleshooting production issues, I find that the more information on the print, the better. If a print has only stock numbers and I am on the line looking at a problem then I do not trust my memory as to the description of for each number and must get to a computer terminal to check descriptions. This assumes that whoever set up the part numbers was generous with their time and did not list 200 part numbers with the identical description "connector" or "lid". When I have had to go to a supplier catalog to find a description of a $100 motor because data entry could not be bothered to make another ten keystrokes, I really wonder about the values of company management. Ten KS at a 30 wpm rate equals about .067 minute vs the 10-15 minutes to research the part number.
If the company has done their homework then special stock sizes are on hand because of specific needs or cost savings. Using a different material causes variations in either quality or cost. If an operator must make a substitution then the more information he has at hand the better he can make the call.
Griffy
RE: How materials should be identified on prints?
I also don't buy the "internal procurement specification" line of reasoning. If the print for AA123 doesn't call out an allowance for a particular substitution, then why are they allowed to substitute? A lack of control in the purchasing department should be dealt with instead of changing your engineering policies, otherwise there will be no end to your misery.
The companies I have worked for in the past have done it both ways depending on what made the most sense for the particular part and standard factory process. Rubber hose would be a good example - it was bought in bulk under one part number but cut into shorter pieces with different part numbers. Stock steel did not normally have a part number as it would make inventory control a nightmare (bad parts, end cuts, waste, etc.).
ISZ