How do I create a Bill of Materials (BOM)?

Overview

A Bill of Materials (BOM) defines the components and subassemblies required to build a finished product. This article walks through creating a new BOM, capturing key fields like quantity-per, scrap, effectivity dates, and backflushing, and validating the setup with a quick test work order.

Applies to: Discrete manufacturing, standard and engineered items
Permissions: Product/Engineering or BOM Maintenance permissions

Prerequisites

• Parent (finished good) item exists in the Item Master with:
  • Correct unit of measure (UOM)
  • Costing method (standard/avg/actual) as appropriate
  • Default warehouse/bin (if required)
• Component items exist with correct UOMs and stocking status
• Routing/operations created (if linking components to specific operations)
• If using revisions: at least one revision created (e.g., Rev A)

Steps

1. Open the BOM module

• Menu path example: Production > Product Definition > Bill of Materials
• Select “New” or “Create” to start a BOM for the parent item

2. Select the parent item

• Enter/lookup the finished good item number
• If using revisions, select the active revision

3. Add components

• Click “Add Component”
• Enter/lookup the component item number
• Set Quantity Per (qty needed per 1 parent)
• Optional fields:
  • Scrap % (planned loss; system will add this to gross requirement)
  • Backflush flag (issue automatically at operation or at completion)
  • Issue Method (Manual, Backflush, Pick/Issue, etc.)
  • Effectivity dates (start/stop) to control when the component is valid
  • Reference designators/notes if needed
  • Link to Operation Sequence (if component is used at a specific step)

4. Repeat for each component

• Maintain logical sequence if your system uses line order for reporting

5. Save and approve

• Save the BOM
• If your workflow uses approvals or status (Draft/Released), set status to Released

6. Optional: Add subassemblies (phantoms or true subs)

• For a phantom subassembly, mark the item as Phantom so its components explode at the parent level during planning
• For a true subassembly, add its own BOM and reference it in the parent BOM

7. Optional: Attach documents

• Add drawings, SOPs, inspection plans, or images to the BOM or parent item

Best practices

• Keep UOM consistency (e.g., parent in EA, components in EA/LB/FT with correct conversions)
• Use effectivity dates for engineering changes rather than hard edits on release day
• Use scrap% for predictable loss, not for one-off adjustments
• Link components to operations for accurate backflush and variance analysis

Validate with a quick test

1. Create a test work order for quantity 1 of the parent
2. Review exploded requirements: ensure component quantities and scrap are correct
3. If backflushing is enabled, complete the relevant operation and confirm component relief
4. Adjust BOM if any component quantities or linkages are incorrect

FAQs

• What’s Quantity Per vs Scrap%?
  • Qty Per is the net requirement; Scrap% inflates the gross planned requirement to cover expected loss.
• Phantom vs Subassembly?
  • Phantom is a planning convenience that flattens into the parent; subassembly has its own WOs and WIP.