Step 1: Standardise properties
An automated BOM is only as good as the data in the models. Define a mandatory property set for every part:
- Part number and revision
- Description (with a naming convention)
- Material and finish
- Part type: make, buy, raw material, phantom
- Supplier and supplier part number for bought items
- Unit of measure
Use templates, dropdowns and validation tools to keep this data complete.
Step 2: Decide which BOMs you need
| BOM type | Used by |
|---|---|
| Structured (multi-level) | Production planning, ERP routing |
| Flat / parts-only | Purchasing, stores |
| Cut list | Fabrication (profiles, lengths, angles) |
| Sheet metal list | Laser / punch with thickness and material |
| Bought-out list | Procurement, by supplier |
Step 3: Extract data through the CAD API
The automation traverses the assembly tree, collects properties and quantities, handles suppressed or excluded components, and merges identical items. It can also calculate values such as profile lengths, sheet areas and weights directly from geometry.
// Pseudo-code for assembly traversal
void Traverse(Component c, int level, double qty)
{
if (c.IsSuppressed || c.ExcludeFromBom) return;
var item = bom.GetOrAdd(c.PartNumber, c.Properties);
item.Quantity += qty;
if (c.IsSubAssembly && !c.IsPurchased)
foreach (var child in c.Children) Traverse(child, level + 1, qty);
}Step 4: Output in the right format
- Excel with your company layout for review.
- CSV or XML for ERP import.
- Direct ERP API integration for items and BOM structures.
- Drawing tables synchronised with balloons.
Common pitfalls
- Engineering BOM structure differs from manufacturing BOM. Plan the mapping.
- Hardware added only on the drawing, not in the model.
- Duplicate part numbers for different geometry.
- Raw material quantities not calculated (length, area, weight).
If a part is not in the model with correct properties, it will not be in the BOM. Automation makes data discipline visible.
Automate your BOMs
ENGIMANDI builds BOM automation and ERP integrations for SolidWorks, Inventor, AutoCAD Mechanical, Creo and more. Read our CAD to ERP integration guide.