Parts Numbering Scheme

[Roger Lascelles]

We are a small company, and we would like to implement a better components
numbering scheme.

The parts numbers need to go into our accounting system and on parts lists,
build lists and some schematics, so we don't want them to be too long.

Letters and digits are OK, but each must start with a letter. Sort order is
a consideration, because computers sort strings from left to right, often in
ascii or similar order. That means each character position has significance
and it might be best if every part had the same number of characters.

The storeroom must be organised by part number, so that we can work
systematically to find the correct shelf, container, then envelope or reel
inside the container. We need to store similar parts together in the
storeroom, to make the most of the containers. For example, SMD resistor
reels are stored together, with a number of different resistor values in
each container. This means SMD resistor part numbers must form a sequence,
though not necesarily in order of ohms value.

A part number should at least tell roughly what kind of part it is - SMD
resistor, leaded electrolytic, etc, so that means the leftmost characters
should carry that info so the sorted list is by part type.

Now, does anyone have a system like that ? Or a different or better system
?

thanks
Roger Lascelles

 

[Dan Hollands]

Since part numbers are entered by hand over and over again into computer
systems the key is to use the smallest number of digits possible.

Part numbers should not attempt to define the part.

I would suggest a 6 digit system xxyyyy where xx is a gross identifier and
yyyy is just a sequential number within the xx class.

Do not use dashes or periods in the part number - that is just one more
keystroke to enter.

Do not use Alpha characters - you should be able to enter the part number
with a key pad for speed.

--

Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com

 

[Boris Mohar]

Since part numbers are entered by hand over and over again into computer
systems the key is to use the smallest number of digits possible.

There is also copy and paste.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

[RST Engineering \(jw\)]

Roger...


35 years ago, when I started RST Engineering, I was restricted to numbers
below the integer-based storage of the computer we had at the time, so all
of our part numbers were 64,000 and below. (+32K to -32K and a subtraction
algorithm that made them all positive).

Fifteen years ago we switched to a 9-digit part number and what a pain in
the labonza to change them all over. However, change them we did and it has
made life one hell of a lot easier.

Send me a decent email address to jim at rstengineering point com and I'll
port you back our internal company document on how the system works.

Basically, it is a number like 1-2345-6789 where the first digit is a broad
class (mechanical component, electrical component, in house made component,
subassembly, etc.), the 23 is a very generic class of parts (and for
electrical parts, 90% of our stock, based on the first two digits of the
Electronic Engineers Master [EEM] numbering system), the 4 breaks it down to
through-hole, smd, etc., 5 breaks it down further (quarter watt, half watt),
the 6 is the tolerance, the 789 is the value in milliohms with the 7 being
the multiplier and the 89 being the significant digits.

The more I think about it, the better I like the first character being a
letter. That gives me 52 options PLUS the 20 some oddball categories of
@#%& non-alpha characters.

Drop me a line. You might also look at a program called Parts & Vendors
that handles this sort of numbering system quite well.

Jim

 

[John Devereux]

Since part numbers are entered by hand over and over again into computer
systems the key is to use the smallest number of digits possible.

Part numbers should not attempt to define the part.

I would suggest a 6 digit system xxyyyy where xx is a gross identifier and
yyyy is just a sequential number within the xx class.

Do not use dashes or periods in the part number - that is just one more
keystroke to enter.

Do not use Alpha characters - you should be able to enter the part number
with a key pad for speed.

Yes, that is just how I reasoned when setting up our database. Our
part numbers start from 1. Maybe I took the principle too far...

We are up to 1654 now. (BFS17W, a NPN RF transistor. Nice part.)

 

[Mark]

Boy, this is one of my pet peeves, the typical part number is
incomprehensible to a human. Untold hours are wasted looking up part
nmbers.

I suggest you invent a part number that is descriptive such as

RES 1000 Ohms 1/8 W 5% 0402 SMD Rev 3

This ASCII string can BE THE PART NUMBER.
You can add as many fields as needed to completely describe the part

Computers don't need random digits to be the part number. They work
fine with ASCII strings.

I would be glad to work with you to invent this new part number system.
We can both become millionaires.


Mark

 

[Richard Henry]

Boy, this is one of my pet peeves, the typical part number is
incomprehensible to a human. Untold hours are wasted looking up part
nmbers.

I suggest you invent a part number that is descriptive such as

RES 1000 Ohms 1/8 W 5% 0402 SMD Rev 3

This ASCII string can BE THE PART NUMBER.
You can add as many fields as needed to completely describe the part

Computers don't need random digits to be the part number. They work
fine with ASCII strings.

I would be glad to work with you to invent this new part number system.
We can both become millionaires.

Agree, if it is smart enough to know that

RES 1.0 KOhms 1/8 W 5% 0402 SMD Rev 3

can be the same part.

 

[Spehro Pefhany]

Agree, if it is smart enough to know that

RES 1.0 KOhms 1/8 W 5% 0402 SMD Rev 3

can be the same part.

Not to mention 1K0


Best regards,
Spehro Pefhany

 

[Joerg]

Hello John,

We are up to 1654 now. (BFS17W, a NPN RF transistor. Nice part.)

And dirt cheap. My impression is that many young engineers don't even
know about these anymore.

Regards, Joerg

 

[John Devereux]

Hello John,


And dirt cheap. My impression is that many young engineers don't even
know about these anymore.

Yes, that too Good job too since I just ordered a reel of 3k. A
lifetime supply at the rate we will use them!

Well, it would be if not for RoHS (as discussed in another thread...)

 

[Dan Hollands]

Engineers often like descriptive part numbers because they rarely have to
enter the part number. They may enter it into a bill of material but thats
about it.

Manufacturing and Purchasing are the groups that spend lots of time entering
part numbers over and over again. When parts are ordered, received, removed
from stock etc. Long alph numeric part numbers not only take more time to
enter but the increase the probability of error.

It is important to get it right from the start. Changing the system later is
a major pain.

The ideal system uses sequential numeric part numbers linked to a
standardized description field. Then reports can be generated for the
engineers that have similar parts grouped together. This makes it easy to
know what parts are already stocked as new products are designed reducing
the rate at which new parts are brought into the system.

A standardized description field is designed for each type of component such

RES 5W 104 SM

It takes considerable work to standardize the descriptions and enforce their
use but is well worth the trouble.

Dan

--

Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com

 

[Joel Kolstad]

Dan,

You have some good insights, but let me add a couple of things:

1) One of the biggest frustrations I've had as a working engineer at a small
handful of companies is that many systems used for entering BOMs are some
horribly old archaic pieces of software that have rotten search facilities. A
smart design would let something like "res 2.2k" find any of "resistor
002.2kilohms" "r 2.2 kohms" or "res 2.2kilohms", yet most have limited exact
search functionality much less the "fuzzier" search needed to find "r 2.2
kohms".

A standardized description field is designed for each type of component such
RES 5W 104 SM

The problem with this is that you can never foresee all the fields you need.
In a reasonably sophisticated manufacturing operator, something like 99% of
your resistors will be something like "10k, 5%, 0805," but there's always that
design where things like temperature coefficients, the build style (inductive,
non-inductive, etc.) matters. This gets even worse with capacitors.

I've had more than one product fail during production due to someone deciding
that they could go and substitute some "run of the mill" part for something
that had tight specs. To avoid that I sometimes will go to the effort to find
a part where the "standard" description (e.g., 2.2uF 0805 25V) specifically
_isn't_ "in the system!"

It takes considerable work to standardize the descriptions and enforce their
use but is well worth the trouble.

....and even with the exceptions to the rules, it's still a lot easier than not
making the attempt.

---Joel Kolstad

 

[Tim Hubberstey]

Engineers often like descriptive part numbers because they rarely have to
enter the part number. They may enter it into a bill of material but thats
about it.

Manufacturing and Purchasing are the groups that spend lots of time entering
part numbers over and over again. When parts are ordered, received, removed
from stock etc. Long alph numeric part numbers not only take more time to
enter but the increase the probability of error.

It is important to get it right from the start. Changing the system later is
a major pain.

The ideal system uses sequential numeric part numbers linked to a
standardized description field. Then reports can be generated for the
engineers that have similar parts grouped together. This makes it easy to
know what parts are already stocked as new products are designed reducing
the rate at which new parts are brought into the system.

A standardized description field is designed for each type of component such

RES 5W 104 SM

It takes considerable work to standardize the descriptions and enforce their
use but is well worth the trouble.

I agree completely. I once thought "engineer readable" part numbers were
necessary and designed my own system where the part number encoded all
sorts of useful (to me) info. This ended up being a nightmare because
the person assigning the numbers had to keep coming to me to check that
new numbers were correct. Then there were the situations that I hadn't
thought of, or were ambiguous. In the end, it generated more work for
many people and didn't really improve anything.

If I had to do it again, I would choose a system based on purchasing,
inventory, and manufacturing requirements. I'd probably use 2-3 digits
to define broad categories (mechanical, electrical, etc.), 1-2 digits
for special handling requirements (ESD sensitivity, fragility, humidity,
temperature, etc.) and 5-7 digits for a sequential stock number. I'd
also include a check digit or two to help detect entry errors
(particularly transpositions [430 instead of 403] and phone/calculator
substitutions [143 instead of 749]).

I would use numbers with fields separated by dashes. This is both human
(numeric keypad) and "barcode" friendly. Dashes reduce human error by
breaking numbers into subunits that fit into our short-term memory.
Numeric+dashes allows use of the less error prone (and shorter)
numeric-only barcodes. Check digits are also required to detect read
errors for most barcodes, so including it everywhere keeps the number
consistent.

Initial entry of the standardized descriptions should be
software-verified, or menu-driven. If the description doesn't match an
established template, it should require someone with management-level
authority to enter an override code. Systems that allow entry without
checks are a recipe for enormous headaches. I would also include a
free-form notes field to help cover those special cases nobody thought of.

 

[Joerg]

Hello Dan,

Manufacturing and Purchasing are the groups that spend lots of time entering
part numbers over and over again. When parts are ordered, received, removed
from stock etc. Long alph numeric part numbers not only take more time to
enter but the increase the probability of error.

That is exactly the point. You need to be able to enter the PN with just
a numeric keypad. Also, in most companies it needs to be suitable for
bar coding.

It is important to get it right from the start. Changing the system later is
a major pain.

In a controlled environment you can't change them later. This can easily
require an ECO re-release of everything that had been designed to date.

Regards, Joerg

 

[Mark]

Manufacturing and Purchasing are the groups that spend lots of time entering

part numbers over and over again. When parts are ordered, received, removed
from stock etc. Long alph numeric part numbers not only take more time to
enter but the increase the probability of error.

Please explain why:

4387645237-045893-001

is less error prone compared to :

RES 1000 Ohms 1/8 W 5% 0402 SMD Rev 3

There's the old story about an army guy that ordered a small audio
transformer to repair a radio and he slipped up on one digit in the
part number.

The transformer finally arrived.. on a flat bed trailer truck. and was
big enough to power a small city.


As far as unforseen variations, you can alway append a small sequence
number at the end as I did using Rev 3 as an example.

Mark

 

[Tim Wescott]

We are a small company, and we would like to implement a better components
numbering scheme.

The parts numbers need to go into our accounting system and on parts lists,
build lists and some schematics, so we don't want them to be too long.

Letters and digits are OK, but each must start with a letter. Sort order is
a consideration, because computers sort strings from left to right, often in
ascii or similar order. That means each character position has significance
and it might be best if every part had the same number of characters.

The storeroom must be organised by part number, so that we can work
systematically to find the correct shelf, container, then envelope or reel
inside the container. We need to store similar parts together in the
storeroom, to make the most of the containers. For example, SMD resistor
reels are stored together, with a number of different resistor values in
each container. This means SMD resistor part numbers must form a sequence,
though not necesarily in order of ohms value.

A part number should at least tell roughly what kind of part it is - SMD
resistor, leaded electrolytic, etc, so that means the leftmost characters
should carry that info so the sorted list is by part type.

Now, does anyone have a system like that ? Or a different or better system
?

thanks
Roger Lascelles

I would suggest that you don't even try to organize the storeroom by
part number. If you do then you will have to dedicate enough space for
each part to accept the maximum amount you may ever have on hand -- and
when you add one miserable little part you'll have to rearrage the whole
room.

Any 1/2-way decent stock tracking program will allow you to track the
locations of any parts, and to print pick tags with the location for the
stock boys. Use one, put the parts where it makes sense, ask the
computer when you're looking for parts and tell the computer when you
move them.

 

[JeffM]

The ideal system uses sequential numeric part numbers

Bingo!

...fields separated by dashes.
This is both human (numeric keypad) and "barcode" friendly.
Dashes reduce human error
by breaking numbers into subunits that fit into our short-term memory.
Tim Hubberstey
Yup.
..
..
Initial entry of the standardized descriptions
should be software-verified, or menu-driven.
If the description doesn't match an established template...
Systems that allow entry without checks
are a recipe for enormous headaches.

Bang-on. BTDTGTTS

Back in the dark ages, our department had 2 copies of the Parts Book:
1 sorted by P#; 1 sorted by description.

Trying to find parts by Description,
it was obvious that the Co. had started with a system
but (over time) the gatekeeper function had been abandoned.
BAD MANAGEMENT DECISION.

(The Co. had also started with a P#-is-indicative system,
but abandonded that--perhaps at the same time.)

 

[Adrian Jansen]

We are a small company, and we would like to implement a better components
numbering scheme.

Suggest you go find out about relational database design. Once you
understand how that works, most of what you want is easy to implement.
Look for keywords like 'Natural key' 'Surrogate key' '1 to many
relationship'.

--
Regards,

Adrian Jansen adrianjansen at internode dot on dot net
Design Engineer J & K Micro Systems
Microcomputer solutions for industrial control
Note reply address is invalid, convert address above to machine form.

 

[Pooh Bear]

We are a small company, and we would like to implement a better components
numbering scheme.

The parts numbers need to go into our accounting system and on parts lists,
build lists and some schematics, so we don't want them to be too long.

Letters and digits are OK, but each must start with a letter. Sort order is
a consideration, because computers sort strings from left to right, often in
ascii or similar order. That means each character position has significance
and it might be best if every part had the same number of characters.

The storeroom must be organised by part number, so that we can work
systematically to find the correct shelf, container, then envelope or reel
inside the container. We need to store similar parts together in the
storeroom, to make the most of the containers. For example, SMD resistor
reels are stored together, with a number of different resistor values in
each container. This means SMD resistor part numbers must form a sequence,
though not necesarily in order of ohms value.

A part number should at least tell roughly what kind of part it is - SMD
resistor, leaded electrolytic, etc, so that means the leftmost characters
should carry that info so the sorted list is by part type.

Now, does anyone have a system like that ? Or a different or better system
?

One of the best I've ever seen, used at a pro-audio manufacturer used a typical
prefix and and sub-descriptor suffix follwed by the value.

E.g. RA100K0 was a 2% 1/4W metal film resistor with value = 100k
RA033R0 was 33R in the same type. Note the use of 4 numerals in both cases to
make listings consistent.

RB, RC etc were different families of resistor type / tolerance / rating etc.

Simialar method used for other parts.

I like the text string idea too. But you need to keep to the format - and that
may be rather less easy to remember.

Graham

 

[Joel Kolstad]

One of the best I've ever seen, used at a pro-audio manufacturer used a typical
prefix and and sub-descriptor suffix follwed by the value.

E.g. RA100K0 was a 2% 1/4W metal film resistor with value = 100k

So what's a 10% 100k resistor? RB100K ???

I tend to waffle about it, but usually I figure that arbitrary numbers are
best -- it doesn't seem there are that many cases where "100k" is the _only_
piece of information you'd like to know about the part, in which case you have
to look up the rest anyway.