Just an idea:
P-xxx = purchased part
M-xxx = manufactured part
P part numbers refer to the itemized parts list where the manufacturers
part number and source are listed
M part numbers would refer to the itemized parts list where the drawing
number is given.
You can't 'idiot proof' anything....every time you try, they just make
Presuming that you're using some kind of parametric 3D CAD system in
which there are links between assembly models, the componet models that
comprise the assemblies, and drawings of both components and assemblies:
You're MUCH better off without a part/drawing numbering system that
assigns any special "intelligence" to numbers . . . to do otherwise is
to invite loads and loads of unexpected work, especially when some
meddling manager decides he doesn't agree with your number assignment
and decides he wants the number changed. Such an action, of course,
would affect your next assembly, the drawings for both the component AND
next assembly, and your BOM (and thus perhaps also your ERP system). If
drawings are released and change paper is required that doubles or
triples the amount of work. In addition you have to be CERTAIN that you
catch all next assemblies (and drawings and BOMs for those next
assemblies) where the component is used that had its number changed, and
very often that's NOT as simple as using some utility to find the "Where
Used" instances of the component. You might be surprised how often
you'll end up being asked to change a part/drawing number, or realizing
yourself that somehow the number assigned isn't quite appropriate and
"has" to be changed. It's a losing proposition . . . BIG time.
It's much better and easier to have the number simply be sequential,
possibly starting with some prefix which can indicate the project to
which a unique part belongs, but even that can bite you in the butt if
you use fabricated parts across product lines. But a descriptive name
FOLLOWING the sequential part/drawing number doesn't really hurt
anything -- doesn't affect how filenames are sorted in Windows Explorer
or in an Excel spreadsheet generated from a BOM (etc.); doesn't cause
problems -- but it CAN make it much easier to identify the kind of
component you're dealing with just by looking at the filename. It can
make it much simpler to find things you need without opening assembly
models or drawings to figure out what is what.
Likewise for vendor parts, descriptive names FOLLOWING other
designations are useful and don't hurt anything. I typically start with
the vendor's name (e.g., McMaster, Southco, Cherry, Vlier, Swagelok,
etc.) followed by the vendor part number followed by a short descriptive
name (e.g., "o-ring, half-inch OD, sixteenth thk"). As I usually do the
initial sourcing for parts I can almost always remember where I found
the o-ring or fitting or electronic component I used, and thus the
vendor name in the filename is helpful in finding things. If a
purchasing agent wants to second-source the part later there's nothing
to prevent it -- in most parametric CAD systems information can even be
included as file properties to identify allowable substitutions -- and
the presence of the original source and part number allows me (or your
engineering department) some control over just how "creative" Purchasing
can get with substitutions. That is to say, when they cross the line of
fit/function/reliability it's a little more obvious and you can a little
more easily put a halt to improper use of substitute parts which aren't
Mark 'Sporky' Stapleton
Watermark Design, LLC
If you're building a machine of any complexity, naming all the parts
can be a real screaming bitch. The best plan is usually just to avoid
naming them at all. As long as they have some sort of part number or
drawing number, manufactured parts will have an identity and don't
really need a "name". It's a confusing waste of time, since what one
person may call a "gearbelt sprocket", another person might call a
"pulley, timing", etc.
And for a one-off, custom machine like you describe, you won't have
customers calling for replacement parts all the time, so there doesn't
even really need to be any long, categorized part numbers. A system of
naming/coding that may seem exquisite to the anal-retentive, seldom
really makes anything simpler or easier. So a hydraulic part starts
with the letter "H"; so what? How does this help?
I have worked at several companies that design and build custom
machinery and most have had very similar numbering systems.
Parts and sub-assemblies in the main assembly are all simply numbered
sequentially, starting with "1". So a punching-station sub-assembly
might be part "1" and the screws that are used to mount it to the main
machine might be part "2". Individual parts get a balloon with the
number inside; sub-assemblies get a double-balloon (circle inside a
circle) to indicate that they are further broken down on another sheet.
All numbers go into a BOM which includes either the sheet that the
part/assembly is to be found on, or the actual ordering information for
On the sub-assembly sheet the parts and sub-sub-assemblies of it all
start with the assembly's number followed by a letter. So sub-assembly
"1" would be made up of parts numbered 1A, 1B, 1C, etc. If there are
sub-assemblies within this assembly, they get a double-balloon and will
be broken down on their own sheet by adding a number. So a
sub-part/assembly of assembly "1G" would break down into 1G1, 1G2,
1G3... You always alternate number-letter-number-letter, so that you
can distinguish multiple-digits (like a part called 12G24).
If you ever need to find a particular part, it's simple. You look at
the main assembly and determine which sub-assembly your part is in,
look up its balloon number in the BOM to find out what sheet it's on
and then look there. You do the same on each assembly sheet until you
reach the exact part you're looking for, which will either be the
machined part drawing or an ordering description in the BOM. No need
for long, fastidiously-coded numbering systems that tell you everything
about a part exept how to get to it. And if you know the part number,
it's even easier to trace down.
Of all the systems I've seen in my career, this one is by far the
easiest and fastest to use. Hope this helps!
But would if a part that is mechanically the same in
always is used in two different complete assemblies?
Example.. say you have a small rectangular steel plate
that measures 1/4x2x6 inches. And that plate is used
in a "head" assembly but also in as a "foot" plate?
Again... its the very same part dimensionally so no
need for two complete drawings of it. Its just used in
two diff "areas" of the machine.
All the more reason to use a sequential numbering system without any
"intelligence" to the numbers. As I noted in my other response, one
could use a prefix that indicates the product in which the component is
used, but even that little can cause problems when components are used
cross-platform. The system that Don (eromligod) suggests is probably in
use where AutoCAD or some similar non-parametric CAD system is used
which does not have associations between component MODEL files and
assembly models and drawings. It doesn't cause nearly the problems
there as it does with Pro/E or SolidWorks or Solid Edge or even
AutoDesk's own (copycat) product Inventor. But even in such an
environment one runs into just the kind of problem that you ("me") point
With Inventor you will definitely run into the problem as I describe it
in my first post. Beware "intelligent" numbering systems -- they will
cost you many times more than you would come to expect by using simple
rational logic, and they will benefit you far less than you would think
as well. Matt Lombard and I are telling you basically the same things
-- he has seen it over and over while working for a reseller, and I have
seen it over and over while working as a freelancer. Both of us have
seen more different scenarios than your average engineer or even many
engineers put together. Is it possible that it won't cost you nearly as
much as we think it will? Yes, definitely, if the company you're
dealing with is extremely careful AND if you don't have political
problems with people who always want to make changes to part numbers AND
if all the users are already very expert . . . but you say you're
"going" to Inventor, which leads me to believe that you (and perhaps
also those you work with) aren't already experts with it. If that's
correct then you're a sitting duck with hunters all around you, and you
WILL get buckshot up the a**. Don't be so naiive as to think it won't
Mark 'Sporky' Stapleton
Watermark Design, LLC
I was using a file naming procedure based on the date I
created the mode;/drawing of the part.
Example.... say I modeled a bearing today. The
drawing/part number is:
where the last two digits, the "01" are just a
So if I did another drawing today it would end in "02".
And so on. I figures I cant do more than 99 drawings in
one day. <G
What abt that system?
And...... should the drawing number and the part number
strive to be the same number?
Whenever you come up with an idea for organizing part numbers you
should ask yourself, "How does this help?". "How is this an
improvement that makes things easier or faster?"
Making the date part of the part number, even though it's already in
the title block...how does this help?
Making the part number match the drawing number...how does this help?
Resetting the suffix number at the end of each day...how does this
help, and in what order should I store the drawings?
For a more complicated part, you're right, you might want to use the
same drawing so that they can all be machined at the same time. No big
deal. Just decide which part number you want to call it and use that
number in all assemblies where the part occurs. So if 12C and 33F are
the same part, just change 33F to 12C in the BOM's. You will have a
"12" part in the "33" BOM, but who cares? No matter which assembly you
look the part up in, it will still direct you to the correct sheet.
There is no law that says all parts in an assembly must have the same
prefix (that would be reverting to useless numbers with "intelligence"
as Sporky pointed out). As long as you can trace the parts, it doesn't
matter. Whether you are looking up a part by its location in the
machine, or by its number, the bills will take you straight to it.
In my experience, alike parts in multiple assemblies do occur, but
maybe only in a couple of places in a machine plan. To let the
machinist make all of a particular part at one time it is also a good
idea to list the total quantity on its part drawing. And to make parts
"backward traceable" you should also list all of the assemblies that a
part is used in on its drawing.
My ideal part system would give a part two numbers: the first would trace to
suppliers and ordering information, including the company it self for parts
made in house and to any drawings, the second would identify where it was
A single part used in two different machines would have the same first
number but different second numbers for each application.
A single part type would change it's first number according to it's supplier
( or even it's batch ).
Sorry, but this is the worst idea I have ever heared.
If you change the supplier, do you want to change all documents, BOMs,
databases etc. where the old part number is stored???
If the part is used in two machines, which machine do you put into the
second part of the part number? Or do you create a new part number for
Greatings from Germany
eMail address is valid but not been read.
No, if you call for a part by it's second number it should ( if you want )
show all supplies.
A new part number for each usage.... this gets round the problem of putting
a description on an invice..... I had two machines from one supplier, and
ordered a part A for machine one, and was supplied with a part B for machine
two, I returned it, and was then told they where the same.......:-(
BOM's use the second number only, production for stock etc is controled by
the first number which should track all alternatives.
first of all:
Never code into the part number (part ID number):
- classification information,
- status or revision information,
- sourcing or manufacturing methods,
- project related (where used) information,
- or any other temporary information which can change during the life
time of a part.
Very bad, because you need a new part number when you use the same part
in another assembly.
Do not assign two part numbers to the same unique part!!!
No matter. One part = one (the same) part number.
Therefore a part number and a part name should not refer to where the
part is used, but only what it is by itself.
Call the plate just "PLATE, RECTANGULAR, 1/4x2x6 in" without regard if
it is used as head or foot plate.
Again: No two different part numbers! No no no! Never!
I invite you to read my Interchangeability rules and Part & Document
Numbering Principles on my web site at:
Greatings from Germany
eMail address is valid but not been read.
You didn't read my follow-up post. Go read it. All parts only have one
number, but you can use that number in any BOM. It doesn't matter.
Really the whole idea of coding part numbers as
"letter/number/letter/number" has nothing to do with some anal-retentive
arrangement (note I use the term "arrangement" as opposed to
"organization"). Arrangement is for nerds who want to f**k around dreaming
up elaborate, aesthetic cataloging systems rather than get machines built
and out the door. I've got other things to do more important than composing
sixteen-digit part numbers (like getting off work at five for a change and
go drink a beer).
The parts could actually be numbered at random. As long as they are placed
in all their respective BOM's and numbers aren't duplicated, they are
perfectly traceable. The number itself is arbitrary...who cares what it is?
The only reason to use the letter/number/letter/number nomenclature I
mentioned is simply as a convenient way to keep track of your number
creation to avoid using the same number twice and to keep numbers short and
simple, to avoid mistakes. There is no practical connection between part
14H and sub-assembly #14 other than the fact that the part occurs in at
least that assembly (though not necessarily exclusively).
The OP also appears to be building a one-off, custom machine, which is what
this system is ideal for. Keeping a special, universal number for a .625
dia. external snap ring that you may or may not ever use on another machine
is pointless. And if you do use a .625 dia, external snap ring on another
machine, what's wrong with giving it a different part number? There's no
reason to stock these parts anyway. If it breaks, look it up in the bill
and buy another one.
If your company produces *production* machines, of course, then it's a
little different story since there will be stocked items used on various
machines. In this case I agree with the suffix-type system, as has been
We have to have 'registered' drawing numbers, per ISO standards, for all
drawings done in house. (And any other documentation, for that matter.)
The system is fairly simple and intuitive.
A 3 letter prefix for each number, each letter stands for something.
Since we have several different design departments, based on product, the
first letter designates the department. For example "Automotive
department = A"
The second letter determines what type of document it is.
For example: A = Automation drawing, D = Durable tooling, M = Machine
part, P = Perishable tooling, etc.
The third letter is the index letter. This is the increment letter for
The second part of the number is 3 digits, and is the actual drawing
number. This is incremented by one for each new drawing.
The third part of the number is the revision level and 2 numbers are
reserved for it.
The fourth part of the number is the sheet number and 3 numbers are
reserved for this part.
So, in effect, you could have a number such as AMC394.21.122, which is an
automotive machine part, 3 rd index drawing number 394, revision 21,
This accurately describes in what book, (cabinet, drawing file) or in
which db to find the drawing, what revision the part was, and on what
sheet of the main drawing file the part resides.
To keep up with and issue drawing numbers, a simple Access database on
the network is used.
By using this database, you can keep up with, and find, the last number
issued, you can also put a description for the part, who the designer
was, for what project, etc.
You can't 'idiot proof' anything....every time you try, they just make
> Say you are building a machine for use in house.
> It has a mix of parts that are buy outs.... and a lot
> of parts home made in the shop.
> What methodology should one use to name or number the
> parts.... both buy out and made in shop?
I build machine tools in small volume, and use a part numbering
system that works like this:
I use sequential numbers (padded with enough zeroes so I'll never
run out of numbers) which reflect nothing more interesting than the
order in which the parts were designed or selected. The first part I
numbered, for the very first machine I ever designed, was part number
The numbers are followed by a single letter to tell me what kind of
part it is. For example:
M = machined metal parts
S = sheet metal
E = electrical or electronic
F = fastener
So, part number 0000108M is the 108th part number I assigned (way
back whenever), and it's a machined metal part.
Since I don't do any machining in house, I know that an M part is
something I buy from a machining source; but other kinds of parts might
be less obvious. I do some fab and sheet metal work, for example; but I
also buy a lot of that stuff. So, part number 0000803S would be a sheet
metal part I make myself, but 0000818SP would be a sheet metal part that
I purchase. That's what the "P" is for.
In some cases, I might be distracted, or in a strange mood, and I
might use a number like 0000155MP. That's redundant, since all my
machined parts are purchased; but it's not misleading or incorrect.
The letter suffix doesn't do anything to the sequence of numbers
when they're sorted on a spreadsheet, or ordered on a Windows file list;
but it makes it easy for me to know what I'm looking for. If a customer
needs a 0001148E, for instance, I know enough to go looking on the
shelves where I keep switches and relays and power supplies, instead of
hunting in the screw bins or the sheet metal racks.
In some cases, I buy things that are a single part number at the
time of purchase; but can be broken down into sub-parts for some
purposes, or for service in the future. An electric solenoid, for
example, has a little link that connects it to something else. That
link is included with the solenoid when I purchase it; but I can also
buy the link all by itself if one happens to break. In that case, the
whole solenoid is part number 00000663EP; but the link is 00000663EP1.
The "1" appears after the alpha stuff, so I know it's a suffix, and that
it means sub-part #1. There might also be sub-part 2, 3, or more.
Some things work the other way, like cable assemblies. I buy cable
in bulk (part number 0001266EP1 on my purchasing lists), and cut it to
length (part number 0001266E2). Then I add connectors 0001266EP3 and
0001266EP4. That results in a finished assembly (0001266E) that I
actually take to the machine assembly area, and that I can sell to
customers as if it were a single monolithic item.
I also use letters like "O" for Optics when I'm building a video
vision or inspection system, or "G" for Granite, when a gauging machine
is built on a granite base plate. And I pretty much add whatever
letters work for me, as long as they're never duplicated.
And, because there are always some things that just won't fit into
any comfortable category, there's "H" for Hardware. That means things
like the little purchased bracket that holds a work-lamp in place, or a
rubber mat on the tool-shelf on a grinding machine, which I cut from big
sheets of corrugated rubber that I buy at retail.
The numbers themselves are all that matter, so the letter stuff is
just to make things easy for me.
I've found that using revision numbers is a problem. If I redesign
something, or even if I buy a newer model of the same thing from a
supplier, I always give it a new part number. That way, when I'm
looking for a part, or shipping one to a customer for service or
maintenance, I never have to wonder if I need the old version of that
motor starter, or the newer version that's a little smaller and has
different screw holes. I also don't have to look at the rev level to
know if I've got the right part. All the info I need is in one place,
within the number itself; and there are no revision indicators on my
prints that might get overlooked. Different parts have different
numbers; and the machine's serial number always points me to the correct
parts list, and to exactly the parts that were used for every machine or
If I modify or retrofit a machine in the field, or even if I install
a newer part number when the old part is no longer available, then I
update the entire parts list for that machine. (That's easy to do on a
computer, of course.) Next time I look up that machine, I'll know that
it's not all original, and I'll be able to compare the original parts
list with the revised one, and see the exact extent of it's modifications.
I try never to have two different part numbers for the same thing.
An M6 x 25mm socket head cap screw, for instance, is always 0000124F, no
matter what machine or model I'm using it in. That helps keep my total
stock of parts to a minimum, and also encourages looking through
existing part numbers at design time to see if I already have something
My system isn't the most sophisticated in the world; but it works
for me, and I don't often get 400 lb. iron castings confused with 1/4
Well, after I've had my coffee that is. Before that, there's no
system on Earth that would help.
I'm sick of spam.
The 2 in my address doesn't belong there.
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