A bill of material, also called a BOM, is a list that includes all the items, parts, and anything else necessary to create a product. The list also includes instructions on how to gather and use all the items listed. In short, a bill of material is both a recipe and shopping list for the final good.

It explains how, what, and where each product will be sourced. All manufactured products begin their life as a bill of materials.

Coming Up with the Bill of Material

The bill of materials puts together all manner of information. Therefore, different disciplines in the manufacturing process will utilize the BOM to do the job right.

In fact, this relationship is so crucial that there are several subsets to the main bill of materials. This helps to streamline all manufacturing activities for the production of a final product. It is especially important for companies that outsource some of their production. Here are some of the types of the bill of materials.

Engineering Bill of Materials: How Many Types Can It Be?

The engineering bill of material defines what the finished product should look like from the design phase. This bill of material will list the components, sub-assemblies, assemblies, parts, and items in the product. Engineers using computer-aided design (CAD) drawings usually create this bill of material. Some products come with more than one BOM depending on their complexity.

It is important that the engineering BOM to be accurate, especially for new products. All the vital components need to be available for the completion of the production process. It ensures that the purchasing department has all the information it requires. That way, it can get in contact with vendors to understand the lead time necessary for each material.

With this BOM in hand, the purchases department can begin negotiations to get the lowest price for these products. If there are any inaccuracies in the quantity or the items listed, it can delay or halt the production of a product.

1. The Manufacturing Bill of Material

The manufacturing BOM contains all the assemblies and parts that are necessary to build and complete a good that can go to shipping. This BOM will include things such as the packaging material required to get a product to the customer. It will also include a list of processes necessary before an item can be officially complete.

The manufacturing BOM will also contain important manufacturing information. It is crucial to the manufacturing resource planning, especially for new products. It is used to decide, based on the estimated delivery date to consumers whether materials need to be purchased and when manufacturing orders should begin.

This process is especially crucial for new products. The manufacturer may only be testing the product before they decide to go into full-scale production. Thus, they may only limit the BOM to about two months. If after the testing the products, they require modifications, the manufacturing BOM can change to fit those changes.

2. A Configurable Bill of Material

Sometimes, a manufacturer can configure a complete product to the requirements of a particular customer. The configurable bill of materials will contain all the components necessary to create a product for a single customer.

3. The Service BOM

Engineers usually develop the services bill of material at the design phase of a product. It will include a list of installation steps, repairs steps, parts, and items that a technician will need to install or service a product.

This bill of materials is different from the operational instructions that come with the packaging for the customers. It is more technical and is only provided to technicians working with a product.

4. Sales BOM

The sales bill of materials is used to create the sales document. In this BOM, the parent item is listed as a sales item instead of an inventory item.

After a parent passes selection, the children will appear as sub-items. In sales BOM, you can update the quantities of children and parent. However, you cannot delete or add new children to the sales document.

5. Assembly BOM

This item is similar to the sales BOM since the parent item will also be in the list as a sales item instead of an inventory item. However, in this document, the finished product will appear in the sales document. It does not contain children as sub-items. It can also be single level or multi-level, as you can see below.

  • Single-Level BOM: The single level bill of materials is in use for products that require a simple production process. This document will usually contain all the parts from the constructing the product. It will usually contain only one level of children in the assemblies, material, and components.
  • Multi-Level BOM: A multi-level BOM suits best complex products. It will contain sub-assemblies, often broken down into other sub-assemblies. In this document, each item number must relate to a parent item except at the top level.

woman signing contract

What Is Necesary for an Effective Bill of Materials?

The bill of materials function is to ensure a product is built flawlessly. Therefore, it is important to include certain pieces of data in any BOM. Here is a list of items it should always have:

  1. The Level: Each part should have a number that details its position in the hierarchy of a BOM. It allows anyone perusing your BOM to understand it.
  2. Part Number: Each part or assembly should have a part number. This makes it easy to identify parts with ease. Always ensure each part has only one part number.
  3. Part Name: Each item should have a unique name. It aids in identifying parts with ease.
  4. Phase: Ensure that you record the stage of each part in the life-cycle of a product. This is useful for tracking the progress and creating projected timelines.
  5. Description: A description with details helps to distinguish between similar parts in the production process.
  6. Quantity: Record the number of parts necessary to make it easy for the purchasing and manufacturing department to make decisions.
  7. Unit of Measure: Ensure that you make it clear which unit of measure is in use. Some parts come from countries with a different unit of measure.

Final Thoughts

Everyone involved in the creation of a product should understand the list of items in a BOM and the types of bill of materials necessary well.

If you prepare it properly, the bill of materials can help to avoid any confusion and save costs for a company.

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