brotherton-erpnext/erpnext/docs/user/manual/en/manufacturing/bill-of-materials.md

Bill Of Materials

At the heart of the Manufacturing system is the Bill of Materials (BOM). The BOM is a list of all materials (either bought or made) and operations that go into a finished product or sub-Item. In ERPNext, the component could have its own BOM hence forming a tree of Items with multiple levels.

To make accurate Purchase Requests, you must always maintain correct BOMs. To make a new BOM:

Manufacturing > Bill of Materials > New BOM

• To add Operations select 'With Operation'. The Operations table shall appear.

• Select the Item for which you want to make the BOM.
• Add the operations that you have to go through to make that particular Item in the “Operations” table. For each operation, you will be asked to enter a Workstation. You must create new Workstations as and when necessary.
• Workstations are defined only for product costing and Production Order Operations scheduling purposes not inventory.
• Inventory is tracked in Warehouses not Workstations.

###Costing of a BOM

• The Costing section in BOM gives an approximate cost of producing the Item.

• Add the list of Items you require for each operation, with its quantity. This Item could be a purchased Item or a sub-assembly with its own BOM. If the row Item is a manufactured Item and has multiple BOMs, select the appropriate BOM. You can also define if a part of the Item goes into scrap.

• This cost can be updated on by using the 'Update Cost' button.

• User can select the currency in the BOM
• System calculates the costing based on the price list currency

Materials Required(exploded)

This table lists down all the Material required for the Item to be Manufactured. It also fetches sub-assemblies along with the quantity.

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