Threaded part description standard

[the_h4mmer]

Silly question to ask, but when making a description for a threaded part, is there standard that states if the fractional or decimal value should be used? To be clear, this is not the callout on a drawing, but the item description (for me in PDM and our ERP system).

I'm asking for a few reasons:
1. I need to standardize how this is done at my organization since it's been a hodgepodge of both
2. I checked with both our ERP technical support and PDM VAR, both state that using ' / ' in a field or variable is not ideal (certainly possible, just not recommended)
3. I'm leaning towards decimal formatting as it's easiest to make uniform across the board and can be helpful when sorting, but I know I'm headed into a battle on this

If anyone knows or can point me to any reference material or standards for what's generally accepted, I'd appreciate it. If no such standard or references are available, then I'm open to hearing people's stance or personal experience on the matter.

[the_h4mmer]

As an Example:

BOLT, EYE, ROUNDED, 18-8 STAINLESS STEEL, 0.312-18 INCH PARTIAL THREAD, 4.625-INCH

vs

BOLT, EYE, ROUNDED, 18-8 STAINLESS STEEL, 5/16-18 INCH PARTIAL THREAD, 4 5/8-INCH

[jcapriotti]

I think the official ASME documentation shows the fractions. We show decimal like your first example for system and data compatibility.

[zwei]

My personal preference will be with fractions...
AFAIK, most system wont complain when handling slash "/", but try to avoid backslash "\" if possible

I believe both approach are generally acceptable.

My ultimate preference will be avoid inches at all, but that only exist in my dream

[dave.laban]

How small do your parts get? If you go the decimal route, would you also be needing to decimalise #10-32 fasteners etc.?

[the_h4mmer]

AFAIK, most system wont complain when handling slash "/", but try to avoid backslash "\" if possible

I asked our PDM VAR if a forward slash ' / ' would be okay as a value in a PDM value, they said that we should avoid the following characters where ever possible:

Code: Select all

( : " ' ; % $ / \ ) @ # ~ ^ !.

My ultimate preference will be avoid inches at all, but that only exist in my dream

Agreed, would much prefer we go all metric

[the_h4mmer]

How small do your parts get? If you go the decimal route, would you also be needing to decimalise #10-32 fasteners etc.?

For these fasteners I would use 10-32 in the description, it would be anything that was not given a #-size. Primarily it's about uniformity in our library. There was a mix of fractional and decimal descriptions for fasteners, and I wanted to standardize.

[the_h4mmer]

Funnily enough, no one at my work seemed to care when I was proposing changes, but now that changes were made, I'm getting flack. I did some digging around, as far as I could find, there is no standard on the file/part/drawing title or description, only the drawing callout:

(ASME B1.1-2003 section 6.):
"...The nominal size is the basic major diameter and is specified as the fractional diameter, screw number, or their decimal equivalent. Where decimal equivalents are used for size callout, they shall be shown in four place decimals (omitting the cipher in the fourth place) for fractional sizes, and in three place decimals for number sizes. ..."

Again, if anyone can prove me wrong on this, I'm happy to learn what's out there. Technically, we're supposed to be based on ISO drafting standards, so if there's something ISO-based, that would be ideal, but I'll take any standard at this point. Failing any external standard, I'll be making my own, so if anyone can help shine light on why using decimal value descriptions would be a bad idea or input on who else it could impact, I'm curious to hear your thoughts.

Who does the description matter to?
> machinists will look at the callout, likely to use a digital caliper
> procurement doesn't care and could use table or look at drawing
> production should reference the part number, not the size/description
> engineering manages the documents and can use look up tables, convert values, or look at drawings
> end users can reference the part number or look up conversion if they want a replacement

My Pro/Con list:

Advantages of decimal
- difficult to get wrong
- does not use ' / ' character (suggested to avoid by both PDM and Epicor)
- descriptions are already updated and uniform for PDM library

Disadvantages of fractional
- easier to type wrong
- will need to update Production parts to fix descriptions (additional time)

[the_h4mmer]

I think the official ASME documentation shows the fractions. We show decimal like your first example for system and data compatibility.

Turns out the ASME standard B1.1-2003 (Section C3.1) also states that for Metric drawings/documents (which is the company standard), to call out or label using decimal format for the nominal diameter; however I wasn't able to find anything pertaining to the Unified National threads per ISO standard. I've shared this finding with management, to which I have received no response, but the drawing that was rejected for using decimal formatting on UN threading was approved yesterday, so I guess that's progress.

[Ry-guy]

As time goes on, much of the data we generate is being used throughout other enterprise systems and even moved to the web. You may find out that all your descriptions and part numbers and such is also being dumped into "data lakes" for even more data analysis and reuse.

I highly recommend not using the special characters as defined by the VAR because the information may cause issues in systems like ERP or database tools. Not to mention that your data may be used by xml or html tools.

Engineering might be the author of the original data in any of the systems- but usually they are also tied to standardized naming conventions that are defined by the ERP/Procurement teams.