BOM Update Tool

BOM Update Tool is a manufacturing utility in ERPNext that allows users to replace an existing sub-assembly Bill of Materials (BOM) with a new version across all parent BOMs. It also provides the ability to update the cost of all BOMs based on the latest raw material prices, ensuring that product structures and manufacturing costs remain accurate.

This tool is especially useful when a sub-assembly design changes or when material prices are updated, eliminating the need to manually modify every parent BOM.

Purpose of the BOM Update Tool

Manufacturing products often consist of multiple levels of sub-assemblies. When a sub-assembly BOM is revised, every parent BOM that references it must also be updated.

The BOM Update Tool automates this process by replacing the old sub-assembly BOM with a new one across all linked parent BOMs. It also helps maintain accurate product costing by recalculating BOM costs using the latest material rates.

Replacing a Sub-Assembly BOM

Whenever changes are required in a sub-assembly, users should create a new BOM instead of modifying the existing one.

After creating the revised BOM, the BOM Update Tool can be used to replace the old sub-assembly BOM throughout the manufacturing structure.

Example Scenario

Consider a company that manufactures Computers. The finished product consists of the following components:

• Monitor
• Keyboard
• Mouse
• CPU

The CPU is manufactured separately as a sub-assembly and has its own Bill of Materials containing:

• 250 GB Hard Disk
• Motherboard
• Processor
• SMPS
• DVD Drive

Later, the Hard Disk is upgraded from 250 GB to 950 GB. Instead of editing the existing BOM, a new BOM is created for the CPU.

Using the BOM Update Tool, users simply select:

• Current BOM – Existing CPU BOM.
• New BOM – Updated CPU BOM.

After clicking the Replace button, ERPNext automatically replaces the old CPU BOM with the new version in every parent BOM where the CPU is used.

How to Use the BOM Update Tool

1. Create the revised BOM for the sub-assembly.
2. Open the BOM Update Tool.
3. Select the existing (Current) BOM.
4. Select the newly created BOM.
5. Click Replace.

ERPNext updates all parent BOMs that reference the selected sub-assembly with the new BOM version automatically.

Limitations

The BOM Update Tool works only for items that have their own Bill of Materials.

It cannot replace:

• Exploded items.
• Individual raw materials.
• Items that do not have their own BOM.

For example, if a Monitor is used directly as a raw material and does not have a separate BOM, it cannot be replaced using the BOM Update Tool.

In such situations, users should either:

• Cancel and amend the existing parent BOM.
• Create a new BOM for the finished product.

Updating BOM Costs

In addition to replacing sub-assemblies, the BOM Update Tool can recalculate manufacturing costs for all Bills of Materials.

Using the Update Latest Price in All BOMs option, ERPNext recalculates BOM costs based on the latest:

• Purchase Prices.
• Price List Rates.
• Valuation Rates of raw materials.

This feature is particularly useful after:

• Updating material prices.
• Replacing a sub-assembly BOM.
• Changing suppliers or procurement costs.

Background Processing

Updating the cost of every BOM can take time, especially in organizations with a large number of manufacturing records.

To avoid interrupting user activity, ERPNext performs the BOM cost update as a background job.

The system automatically processes every BOM and updates its manufacturing cost without requiring users to wait for the process to finish.

Automatic BOM Cost Updates

ERPNext also provides the option to update BOM costs automatically.

By enabling Update BOM Cost Automatically in the Manufacturing Settings, the system recalculates BOM costs on a scheduled daily basis using the latest raw material prices.

This helps ensure that manufacturing costs remain accurate without requiring manual intervention.

Business Benefits

• Automatically replaces revised sub-assembly BOMs across all parent BOMs.
• Eliminates manual updates to multiple manufacturing structures.
• Keeps manufacturing costs aligned with current material prices.
• Supports background processing for large-scale BOM updates.
• Provides automated daily BOM cost recalculation.
• Improves manufacturing accuracy and consistency.
• Reduces maintenance effort for complex multi-level BOMs.

Key Summary

BOM Update Tool in ERPNext simplifies the maintenance of multi-level Bills of Materials by allowing users to replace sub-assembly BOMs across all parent BOMs and recalculate manufacturing costs using the latest material rates. With support for automated cost updates and background processing, the tool helps manufacturers maintain accurate product structures and reliable production costing while significantly reducing manual effort.