Part Numbering - Tabulation vs. Length Per Order vs. Significant Numbering 1

[Slagathor]

I am a believer in the following:
-Some minor form of significance in the part number. Mainly to make it easier to transpose and recall the "important" part of the PN..and make that part "smaller"...ie for 'useablity'.
-No significance in the key part of the number.
-Using field based descriptions to find parts that you do not have memorized cold. We have a slick. dynamic, DB based system we are currently coding which we think will be a quantup leap over the single string "Description" text field in our MRP system which is worthless.
-Possibly a tabulated suffix where useful

Here is a proposed tabulated Part and Document Numbering system:

Part Number:
123-4567-1A (this is a tabulated part, and 1A would represent the 47th (not 48th, as 00 is not used for tabulated parts per below) tabulated option described in the tabulation scheme on the Part Drawing Doc)
123-4567-00 (-00 is used ONLY when a part is not tabulated, and there us only ONE part using this base number. 97% of parts will not be tabulated, but those that are will save thousands of base PNs and Docs)

Document Numbers:
P123-4567 (Part Mfg Drawing/Document)
C123-4567 (Part Coating Drawing/Document)
W123-4567 (Part Weld Map Drawing/Dcoument
A123-4888 (Assembly Drawing)
Etc Etc.

Documents have a letter prefix (P, C, W, A, etc), and include the same base number (123-4567) as the part number to eliminate cross reference tables, etc. to ID the Doc type. It never has a tabulated suffix. If the part is a single item, and not tabulated, the Part Number on the drawing title block will show ###-####-00. If the Part is tabulated, and there are tabulated configurations, the Part Number on the drawing title block will show ###-####-_ _.

123 is a part family code, thus has minor significance. We have about 25 major part families. So, 123-128 might represent "drive shafts", and in time, people will memorize this. They will essentially not need to think about this part of the number. The will know whey they see any part starting with 123, 124, 125, 126, 127 or 128 that the part is a "drive shaft"

4567 is completely non-significant. So, if we have 123-128 set aside for "drive shafts", this means we have 60,000 available part numbers for drive shafts. We might very well be able to drop this portion to 3 digits, and have 6,000 part numbers.

1A (alphanumberic = base36, sort of hexadecimal on steroids. Two digit base36 = 1296 tabulations possible with two characters) is the part I am wondering about. In his "Engineering Documentation Control Handbook", Watts is a big advocate of this. We have MANY parts that have variable lengths. For instance, one such drive shaft can be anywhere from 18" to 120", in 1/8" increments. The ONLY variable is length. In the past, we handled this as an LPO (Length per Order), which severely limits the ability to plan materials. We must have a system where a part number for a specific length column has a unique PN, and can automatically evaluate material requirements (for instance, a know length of required raw material based on the PN)

A tabulated system 'seems' to be a good way to do this.. The idea behind a tabulated system is that the tabulation is defined on the drawing (P123-4567), and there is a lesser degree of intelligence in the number. This makes it more flexible/robust. The problem is in my example, this would require 816 separate tabulations! (120-18)*8 = 816!

So, to deal with this situation, here are the options:

*No Tabulation, and generate 816 part numbers and drawings. Sorry...but no way.

*Use tabulation. The drawing P123-4567 would have 2 sheets. The first would be the drawing, with Length shown as "per tabulation, see Sheet 2". Sheet two would describe the tabulation numbering scheme. -01 = 18" / -02 = 18.125" / -B1 = 30.875". This would result in a 23 x 36 tabulation table on page two of the drawing!. This might actually be a good thing, as there would only be 20-30 of these master tabulated drawings, and it would force shop floor people to pull the drawing to check the tab code. Also, the description in the ERP system will include the correct length, so they can always look there to confirm.

*Add a significant suffix. Ditch the two digit base tabulation, and come up with a flexible smart suffix system that is shorthand for length. In other words, instead of 123-4567-B1 for 30.875", we would have 123-4567-0307 (0307 stands for 030" + 7/8" = 30.875". 0180 would be 18.00". 1197 would be 119.875"). What I do not like about this, is the tabulation scheme is inconsistent. What about a case where we are not tabulating lengths, but combinations of features. For instance, we may have 12 parts that can be machined from the same base casting, and these could all be represented on a single tabulated drawing. -0012 or -12? Using the smart suffix for different things could create confusion. With the 1A system, people will KNOW they have to look up the tabulation master table on page two of every tabulated part.

I am leaning towards the base36 two digit tabulation. It seems more robust and flexible, but will likely result in some griping because a people will have to look up the tabulation scheme.

Opinions?

 

[MadMango]

People will still have to look-up the tabulations, even using a simple 3-digit tabulation, yielding 999 variations. I don't like the Base36 simply because people will confuse O for 0 and I for 1, etc.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[Slagathor]

So Madman, would you recommend tabulations, but with numbers only? 123-4567-### = 999 possible tabulations for a base part number?

If the Os and Is were dropped, that would result in base 34, where 2 digits = 1156 combos. I agree that numbers only, 3 digits is probably better. After all, 97% of the time, PNs in this scheme will not be tabulated, and there will be only one unique item per base part number, and it will always end in "-000", meaning no brainpower will have to be expended thinking about the suffix.

 

[MadMango]

You have to do what is best for your situation, but I think tabulations are common, and the -000 would be fool proof.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[KENAT]

forum781 is arguably a better place for this type of question.

General consensus there is that intelligent part numbering schemes aren't so intelligent.

There will always be exceptions but our scheme which uses a 3 digit first block that is 'intelligent' is a mess. When you have that many categories it's not always clear what goes in what categorty as they still aren't specific enough to capture every possible item.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Slagathor]

KENAT,

Thanks, I did not realize that forum existed. Moderator please feel free to move....

As for the 3 digit first block, the groupings are VERY broad, and specific to our product. In reviewing them...there are actually fewer than I thought. Less than 20. We do not think it will be too hard to determine clearly where things go. We could probably take it down to only a two digit prefix, and then make the middle number 5 digit. That would provide 100,000 numbers in those 5 alone. More than enough.

In this case, we could then make the 5 digit middle code unique less the prefix. In other words, once 12-12345-### is assigned, you could not use 13-12345-###. the -12345- can only be used once. In other words, 12- is not actually a unique part of the ID number. It is a separate field.