BOM Assigns two different item numbers for same parts under two different sub-assemblies.

[amini.mhd94]

What I need is one part has a unique item number under all different sub-assemblies.

For example, in this case we have "support2" with Item number "1.3" under sub-assembly "1" and Item number"2.3" under sub-assembly "2". I need a unique number for this part as "1.3".

How can I prevent BOM to assign new Item numbers under each sub-assembly?

Can anyone help me with this?

Thank you

[PaulMunford]

Hi @amini.mhd94 

This BOM view is designed to give a hireachical item number, which tells you where the component is located in the design. Because the components are used in mutiple places, the hirearchital item number reflects this.

There is also the option of a 'flat' BOM, in which hirearchy is ignored. No sub assemblies are listed - only parts are listed, and each unique part has it's own item number.

Is that helpful?

[swalton · Accepted solution]

The BOM or Parts List item number is used as a one-off index number that can and will change as assemblies are modified over time.  

We assign a unique part number to every component in our system. If we need to refer to a component, we use the unique part number, not the BOM/Parts List index number.

We also use the part number=drawing number=file name convention.  Again, that gives us a unique identifier for each component that is used once-and-only-once throughout our CAD, Vault, Purchasing, Manufacturing Documents, Receiving, etc.

[johnsonshiue]

Hi! Inventor 2023 has a few enhancements in BOM workflow. One of them is about the ability to lock the item number. Please take a look at the What's New page.

https://help.autodesk.com/view/INVNTOR/2023/ENU/?guid=GUID-C0084FE2-066F-432F-8E67-D4F9ECDD210D

Many thanks!

[cadman777]

I still do it the old way b/c I use an older version of Inventor.

Like @swalton I manually create the BOM ItemNumber.

My number is a composite number that's for identification purposes.

So you can make your own number any way you want using any number of iProperties combined into one number that shows up in the BOM/PartsList. If you use Excel, just think of it like Excel's Concatenate, except you're doing it the Inventor way.

The key to numbering is to number at the very end of the project.

But if you don't do that, when you have your own ItemNumber, it doesn't matter, b/c the ItemNumber won't change automatically and it will remain constant on a per-part basis throughout the project's life-span, compared to using Inventor's build-in numbering system.

Numbering is a critical topic in the engineering world that's little discussed and hardly acknowledged.

To reiterate, numbering at the end of a project before drawings are released (if possible) is a 'best practice'. 

Otherwise, you would need PreliminaryNumbers and then ReleaseNumbers, or something along those lines.

But then the whole thing gets even more complicated.

[blandb]

@johnsonshiue 

So, does this mean if "part a" has been marked as item "25" in a parts list and has been "locked", when that item is used again, it will be "25" by default?

[cadman777]

Does that means the ItemNumber can be 1.1, 1.2, etc and not change in sub-assemblies using the same part?
I'm curious what benefits were envisioned by the developers for adding this BOM function?

The confusion part of this for me is, 2010 already has LOCKING ItemNumbers.

So what benefits were envisioned by making these minuscule changes?

Do the ItemNumbers propagate throughout every BOM where the part is used throughout the project in different sub-assemblies? 

[johnsonshiue]

Hi Brad and Chris,

I am extremely sorry that I posted a confusing reply. The change is about the appearance (text and font) of a locked item. The ability to lock item number remains unchanged. The item numbers are still stored in the iam file where the particular BOM exists. I don't think they carry over elsewhere.

Many thanks! Sorry for the confusion!

[cadman777]

Thanx for the clarification Johnson.

So basically the 'developers' just 'rearranged the furniture'!

[amini.mhd94]

Steel have problem 🙂

In the drawing of this part (Support2), I want to have a parts list with unique item number -like first assigned item number in BOM (here is 1.3)- , and total quantity shown (here is 36). something like screenshot below:

(I typed in the cells manually but I need Inventor to assign it automatically)

In fact I need hierarchical parts list for sub-assemblies and this parts list for single parts.

The parts list I need for sub-assemblies is like screenshots below:

I created these parts list according to main assembly file and then hid other unwanted rows.

The other problem is balloon numbers. they do not match with these hierarchical item numbers.sub-1sub-2

This kind of numbering is very reliable and we can follow each item in large assemblies with lots of drawing sheets. And we will not need a separated list that indicates total Qty of each parts. The total Qty would be in the drawing 🙂

[swalton]

Inventor is not designed to work as a work order system.  It does not have good tools to keep Parts List item numbers and quantity needed information up to date on drawings.

The most robust choice is to implement an ERP or similar software system outside of Inventor to track this information.

There are a few workarounds if you must stay in Inventor.

Ground Rules:

• Inventor provides the Part Number iProperty as a unique, unchanging identifier for each component.  If you are not willing to use this iProperty, then accept that the Item Number can and will change as you add/remove components from an assembly.
• A part that is used in two different sub-assemblies will have a unique item number for each sub-assembly.
• Inventor wants to display a Structured Parts List or a Parts-Only Parts List in a drawing file, but not both.
• Item Numbers are an assembly property.  They are not stored in a sub-component file. 

Work-Arounds

1. Document the parent assembly and each sub-component in the same drawing file. 
   1. If the parent assembly has 200 sub-components then there will be drawing views of all 200 sub-components in a single file.
   2. Create a Design View rep that isolates each sub-component in the parent assembly file.
   3. Use those View reps to detail each sub-component in the drawing file
   4. Place All-Level Structured Parts Lists near each sub-component and filter them by the proper Design View Rep.
      1. This may show two different item numbers and counts if a component is used in two different sub-assemblies.  Test and see if the behavior works for you.
   5. If a component is used in different parent assemblies, you will have to detail it in both drawings.  It will very difficult to make sure any revisions to the component are captured and documented in all the proper drawings.
2. Document each component in separate drawing files.
   1. There may be some iLogic that can be run in the parent assembly or drawing to push the Item Number and usage count down into Custom iProperties in a sub-component.  Internet searches or the Customization forum will help you find them.
   2. Run those rules on the files.
   3. Create a custom Parts List template that displays the count and item number data.
   4. Detail each component in a new drawing file.  Make sure to include the custom Parts List and attach it to the component.
   5. I'm not sure how to manage the different item numbers and counts if a component is used in several different assemblies. 

The workarounds are not complete workflows and will need development and testing to ensure they meet your requirements.

[cadman777 · Accepted solution]

This is way too complicated and error prone.

The simple solution is to have one number for each part that's embedded in the part itself as an iProperty.

And make that iProperty system-wide.

The way I did that was to make one iProperty that all parts possess called 'MARK'.

Every discrete part in every project has it's own MARK number.

That MARK carries through to every subassembly in that project.

So, only one MARK number exists for each discrete part in every project.

If parts share between projects, and if they are identical, then they have the same MARK number.

No need for an elaborate ERP/EDDMS system.

If you want to merge your MARK number with your accounting system, then you can do that by adding iProperties.

No iLogic necessary.

Really, it's that simple.