Drawing Title = Part Name, Drawing Number = Part Number?

S1mon

I recognize that there are a lot of different ways that companies like to do this, but here's a two part discussion:

For Part 1, let's assume the goal is to have the drawing title be the same as the part name. I know I can just edit the drawing template so that instead of Sheet Reference:Title 1, Title 2, Title 3, we just have Sheet Reference: Name. Are there other approaches that people like to use?

For the drawing number, I'd prefer to have one prefix for the drawing and a different prefix for the part, but use the same number (e.g. EQD-00012 and EQP-00012 for drawing and part, respectively). In the numbering scheme preferences, there's a checkbox for "Drawing can reuse part number from an assembly or part in the release". I assume this just means that I can manually reuse the part number in a drawing number? It's not clear.

I want to avoid copying and pasting information, but I could see a custom feature which massages some properties. How do people manage systems like this?

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Part 2 of this discussion involves asking if it makes sense to have Drawing Title = Part Name, Drawing Number = Part Number? 

I've worked with teams in the past that found it too confusing to have a drawing of a part and the part itself have two different numbers and revisions. I've also worked with teams that didn't want to send out the same 3D files when only the 2D drawing had changed (e.g. some notes were updated). Depending on how you do release management, these two approaches can drive you to want all these names/numbers/revisions to match, or they can encourage you to have separate nomenclature which is connected by PDM and/or PLM (or worse, by some spreadsheets that get emailed around).

In more complex situations, you might have several different drawings which refer to the same part or assembly (e.g. an exploded view with item numbers for a BOM, or a dimensioned drawing for incoming inspection). These might want different titles, different numbers, and different revisions. When is this level of complexity justified?

nick_papageorge073

Part 1: I use the 3D description for the title block on the 2D. Then for "name" on the 3D, I type the PN + Description.

The reason is when you export a 3D asm for a vendor, all the components in the tree upon the STEP export take "name". I want them to have a PN for the vendor. But for me internally, I want text there so I know what is what, which comes in super handy when modeling. The export of assemblies' internal components does not follow the export rules.

I don't know if this is the best way, but I found it worked for me, after trying a couple of other ways.

S1mon

Let's say part name is something like "Bracket, Left" and part number is "EQP-00012". The export naming rule I like for the 3D is "${name} ${partNumber} Rev{revision}.{export.format}" (e.g. "Bracket, Left EQP-00012 Rev003.step")

That also goes on the drawing as a note "REFER TO ${name} ${partNumber} Rev{revision}.{export.format} FOR 3D DATA."

I'm not using the part description, since I like the names to be reasonable enough to understand. So the drawing title can just be "BRACKET, LEFT".

S1mon

I dug this up for further discussion. From the book "Bills of Material for a Lean Enterprise" by Dave Garwood:

Part Numbers and Drawing Numbers

Another question is whether the part number should be the same as the drawing number. In the process industries, instead of drawing numbers, there are process sheets, specification documents and similar documentation. They still face the same problems.

The thing to keep in mind here is that the part number and the drawing number serve different purposes. The part number is the unique identifier of the item, while the drawing number identifies the visual aid for making the item. If the drawing number and the part number are the same, you run into many potential problems.

The same drawing might be used for several different parts that may have the same dimension but are made from different materials. A new part can be created, requiring a new part number, without necessarily requiring a new drawing. For example, a situation where the tolerances for an item have been changed.

The new tolerances make the part different, requiring a new part number. However, the drawing may only require a change in the drawing revision letter, not an entirely new number.

In some cases, a part number may be required without the need for a drawing - bar stock, steel coils or some other raw material, for example. People might be confused while searching for drawings that aren't there.

If there will always be only one unique part or item made from each drawing, the same digits can be used to identify both.
When the variations from the same basic drawing start to evolve, the problems begin. Many times companies try to use the drawing number as the base number and affix a dash number as a suffix to create the part number. Although the hybrid approach can be made to work, it's unwieldy and we don't recommend it.

There's no reason to go looking for trouble. Keep the part numbers and the drawing numbers separate to avoid potential problems.

Again, any subassembly that is stocked should have its own part number. Phantom part numbers can be assigned to transient subassemblies and "bag of parts" type subassemblies that are not stocked.

The advantages of not having the drawing number the same as the part number include:

1. Shorter part numbers
2. Fewer bill of material errors
3. Less confusion; less paper-shuffling
4. Fewer material issuing errors
5. Fewer drawings, because one drawing number can relate to many part numbers
6. A new drawing may not be needed when a new part number is needed

I have some misgivings with this. In the example of new tolerances requiring new a new part number, it seems weird that you would have the same drawing number but just a new revision. That seems confusing too. I also like the idea of variants (AKA dash numbers) for things like different color ways or other more subtle changes to a basic part. I've seen things like connector drawings which have a table with number of pins as dash numbers and then a few key dimensions which change depending on the number of pins. 

Some questions: 

1. In any of these situations is the thing that you order the part number or the drawing number?
2. What's the easiest way in Onshape to see a table of part numbers and drawing numbers associated with them (especially if they aren't the same)?

nick_papageorge073

S1mon said:

Let's say part name is something like "Bracket, Left" and part number is "EQP-00012". The export naming rule I like for the 3D is "${name} ${partNumber} Rev{revision}.{export.format}" (e.g. "Bracket, Left EQP-00012 Rev003.step")

That also goes on the drawing as a note "REFER TO ${name} ${partNumber} Rev{revision}.{export.format} FOR 3D DATA."

I'm not using the part description, since I like the names to be reasonable enough to understand. So the drawing title can just be "BRACKET, LEFT".

That does not apply however when you export a complete asm as a step file for a vendor to use in another cad system. When they open up the asm in Creo/SW/Fusion/etc, their asm part tree will show only Onshape "Name". They won't know what the PN is they are looking at unless it is added to "Name" within Onshape. I wish the export rules applied to assembly instances, but they do not.

And on our side, if we make "Name" equal only to PN (which I know some Onshape companies do), the engineer will not remember what PN is what part. This is particularly a problem when you are in a part studio and picking merge scope, for one example. Its so much nicer for the "Name" to be something we can instantly know what part it's referring to.

Urs_Egger_REACT

@S1mon you opened pandoras box    - Let me know when you have found a solution. Then we can address the issue with the ERP article numbers in combination with the CAD part numbers and CAD drawing numbers in combination with part color variations. 

S1mon

Yeah, a lot of these decisions are complex and really depend on the company and situation. In this case I’ve leaned towards independent drawing and part numbers, but it’s making me a little nervous in terms of how easy it will be to see in one place what drawings go with what parts. 

romeograham

I do it in a similar way, @S1mon . Part: P1234 - and its associated drawing D1234. with the Revision property used in the exported part name (we build the exported part name from

"${prtNum}-REV-${rev} ${size/CapacityForNameOnly} ${description} (from ${documentNumber})" Where size/capacity and documentNumber are custom fields we need to fill in manually in the properties for parts, assemblies and drawings.

(Some of our team uses Letters for 3D part/assy revisions, and Numbers for 2D drawings - this makes it easy to update a drawing rev for a color note or tolerance update.

The documentNumber is a nice one for breadcrumbs back to the document if you find a PDF/print lying around somewhere.

For drawings that are needed for different purposes (inspection, for a customer, work instruction etc) we'll append something useful on the Drawing Part number (or Part Number for the part). That way it is conceptually connected (manufacturing drawing: D1234-REV-1...PDF, inspection drawing: D1234insp-REV-2...PDF).

Of course, like every other numbering system with a formula or recipe built into the part name or number, it immediately breaks down under any kind of unique situation or scrutiny.

I do really like to keep the numerical part of the Part and Drawing connected. The main "useful information" that's missing from this approach is that you can't see from a drawing part number (D1234) if it's referencing a Part or Assembly. Main problem - and I don't like that part. Therefore, "Assembly", "ASM" , "Assy" etc must be included in the Description of the drawing to make sure it makes it out with a PDF export of the drawing.