Create a bill of materials (BOM)

A bill of materials (BOM) lists everything one batch of a product consumes. Work orders copy it, scale it to their quantity and use it to reserve, issue and cost the materials. A product needs an approved BOM before it can go into production.

Before you start

• The finished product and every component must exist as items. See Create an item.

• If you buy or count a component in more than one unit, set up its units first. See Units of measure.

Create the BOM

1. Open Manufacturing › Engineering › Bills of Materials and select New BOM.

1. Choose the Product you are describing. Then complete the header:

   • Type: manufacturing, engineering or planning.

   • Version: starts at 1.0. Use it to tell revisions apart.

   • Output unit and Base quantity: the quantity of product the component lines below are written for. A base quantity of 100 with a unit of kg means "these components make 100 kg".

   • Effective date and, if the recipe is temporary, an Expiry date.

   • Yield: the percentage of good output you expect, from 1 to 100. A yield of 95 makes the system plan about 5% more of every component.

   • Scrap item and Scrap expected quantity (optional): the item that receives recoverable scrap from the run.

2. Under Components, fill one line per material. Select Add component for each extra line:

   • Component item, Quantity and Unit. The unit list shows only the units defined for that item.

   • Component type: raw material, sub-assembly or purchased part.

   • Scrap %: the expected loss of this component. A 5% scrap adds 5% to its planned quantity.

   • Optionally an Operation sequence, an Alternative item with its Unit, the Critical switch and Notes.

3. Under By-products (optional), select Add by-product for each secondary item the run produces. Enter the By-product item, Expected quantity and Unit.

4. Select Save. The BOM is saved as a draft.

How the quantities are used

When a work order is created for, say, 250 kg of a product whose BOM base quantity is 100 kg, every component quantity is multiplied by 2.5. The yield and each line's scrap percentage then raise the requirement. Component units are converted to the item's base unit, so you can write one line in kg and another in grams.

What happens next

A new BOM is a draft. You can edit or delete it until it is approved. Approve it when it is final: see Approve, clone and version a BOM. Then create the routing for the same product.

Common questions

Can a component itself be manufactured? Yes. Mark it as a sub-assembly and give it its own BOM and work orders.

Where do I see what the BOM costs? Open the BOM from the list. The detail page shows the cost of each component line and the total, based on the items' current cost.