AI for Parts & BOM Management
AI BOM generation from a CAD assembly: roll up quantities, catch static overrides and check every part number before release, with a worked example.
·
⏱
4 min read
Dr. Maor Farid
Maor Farid is the Co-Founder and CEO of Leo AI, the first AI platform purpose-built for mechanical engineers. He holds a PhD in Mechanical Engineering and completed postdoctoral research at MIT as a Fulbright fellow. A Forbes 30 Under 30 honoree and former AI researcher, Maor leads Leo AI's mission to help engineering teams design better products faster.
BOTTOM LINE
AI can draft a BOM from a CAD assembly in minutes, but the quantities decide whether it is usable. Recompute the roll-up from the assembly structure, scan for static overrides, and confirm each purchased part exists in the item master. A BOM that passes those checks is ready for approval. Leo can draft one from your PDM and ERP data.
An AI-built BOM is usable only if its quantity roll-up matches the CAD structure, so check the roll-up before you trust the part list. If your team builds BOMs from Autodesk Vault or Inventor assemblies, the common defect is a quantity that no longer matches the model.
One invented pump skid below shows the count breaking. A one-week test then shows whether an AI-built BOM survives the same change.
Static quantities drift when the CAD model changes
Autodesk Vault stores each BOM quantity as calculated or static. A calculated quantity comes from the source CAD file. A static quantity overrides the quantity in the linked CAD file, and the CAD value is no longer reflected in the BOM.
Inventor has the same switch. Its Calculate Quantity/Static Quantity control decides whether a Quantity cell is calculated or overridden in the BOM.
Overrides are legitimate for non-CAD items. Vault requires a quantity for non-CAD items because there is no CAD data to determine it. The defect appears when a static value stays on a modeled part after the design changes. The BOM keeps the old count, and nobody sees the gap until purchasing or assembly.
Inventor also separates BOM views. Structured is an actual BOM view reported in a parts list, and Parts Only shows all components in a flat list. Confirm which view you hold before you compare two sets of numbers.
IN PRACTICE
The geometry search has been invaluable, helping me find standard parts instead of designing new ones, saving a huge amount of time and effort. The search system is smart and CAD-aware.
- Eytan S., R&D Engineer
A first-pass BOM is built in six steps today
For the pump skid in the next section, steps 1 to 3 touch 12 line items across 3 levels.
Open the top assembly and set the BOM to the structured view, so each subassembly keeps its own quantities.
Export the BOM and mark every line that has no part number in the vault or the ERP item master.
Add non-CAD items (washers, adhesive, labels) with static quantities and a note on why each is static.
Match each purchased part to an item master record by size, grade and finish.
Compare the CAD roll-up with the ERP quantity for each purchased part.
Release the EBOM, then derive the manufacturing BOM from it. The EBOM to MBOM handoff covers that step.
Steps 4 and 5 are manual lookups, one purchased line at a time.
Worked example: rolling up a pump skid BOM
The assembly is invented for this post. Each quantity is per parent, and the rolled quantity multiplies down the branch.
Item | Qty per parent | Rolled qty |
|---|---|---|
Base frame weldment | 1 | 1 |
Hex bolt M10x30 | 4 | 4 |
Flat washer M10 | 8 | 8 |
Hex nut M10 | 4 | 4 |
Motor bracket assembly | 2 | 2 |
Bracket plate (in bracket assembly) | 1 | 2 |
Socket head cap screw M8x25 (in bracket assembly) | 4 | 8 |
Flat washer M8 (in bracket assembly) | 4 | 8 |
Coupling guard assembly | 1 | 1 |
Guard shell (in guard assembly) | 1 | 1 |
Button head screw M6x12 (in guard assembly) | 6 | 6 |
The skid needs 38 fastener pieces in total: 4 + 8 + 4 + 8 + 8 + 6.
Now the design changes. Each bracket gets 2 extra holes, so the CAD model holds 6 M8x25 screws per bracket. Someone had set the screw line in the bracket assembly to a static 4.
Calculated roll-up: 2 brackets x 6 screws = 12 screws.
Static roll-up: 2 brackets x 4 screws = 8 screws.
Shortfall: 12 - 8 = 4 screws, and 4 matching M8 washers if the washer line is also static.
The BOM looks complete and prints without an error. The shortfall shows up at assembly.
Test an AI-generated BOM on 20 of your assemblies in one week
Pick 20 released assemblies of different sizes and run five tests. Each has a pass criterion you can state before you start.
Roll-up test: recompute every quantity from the assembly structure with a script. Pass: 20 of 20 assemblies match on every line.
Override scan: list every static quantity on a modeled part. Pass: each one has a recorded reason.
Item master match: look up each purchased line in the ERP. Pass: every part number exists, and every new number has a named reason.
Change test: add one hole pattern to a copy of one assembly and regenerate. Pass: the BOM quantity moves by exactly the number of added holes.
Time test: log minutes per assembly for manual build and for AI draft plus review. Pass: the review time is under half the manual time.
A failure on test 1 or 4 stops the rollout. Quantity errors cost the most downstream, and the BOM validation checks cover the other error types.
Generating the BOM in Leo from your own PDM and ERP data
Ask Leo for a first-pass BOM of the pump skid and tell it to prefer parts you already stock. Leo reads the assembly from your PDM or PLM, and it reads network directories and the ERP item master, so each line can point to a part number you already own.
For the fasteners and washers, Leo can also search your parts by shape, which finds a stocked M8 screw even when its file name says nothing. The geometric search guide shows that search in detail.
Treat the result as a proposal. Your PDM and PLM stay the system of record, and an engineer approves each line. One limit applies: Leo is an AI assistant, so run the roll-up test from the previous section on any quantity before release. For data handling, see the security page.
FAQ
Try Leo on your own assemblies
Ask an applications engineer how Leo reads your PDM and ERP.
Bring one assembly and its current BOM. See how Leo drafts a first-pass list from your own CAD, PDM and ERP data, then check the roll-up yourself.
#1 New AI Software Globally - G2 2026
Enterprise-grade security
Trusted by world-class engineering teams
