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Bill of Materials FAQs

Bill of Materials FAQs

You’ve heard of it. You need it. But you’re not quite sure what it is. A bill of materials – or BOM now that you’re going to be an expert – is a comprehensive list of materials required to build an entire product. A BOM is basic a recipe for creating a finished product outlined in hierarchical order. But, you have questions as do so many others. Let’s take a look at the most common bill of materials FAQs to help you out.

FAQ1: Why is a bill of materials important?

The BOM is an important list that provides businesses with a complete, accurate overview of the inventory required and the process involved in creating a single product. These are essential tools to ensure that a company operates unimpeded while also reducing errors.

With a comprehensive BOM, there are no wrong parts ordered or incorrect quantities used that could delay delivery. In addition to the material list and quantities, the BOM details the tools and equipment needed for the assembly and sub-assembly to manufacture the product.

FAQ2: What are the types of BOM?

Don’t get overwhelmed, but there is actually more than one type of BOM. However, this is determined by the industry you’re in, so you’ll likely only need to have a firm grasp on one BOM type. But just to increase your knowledge base on this particular subject, here’s a look at the different ones available.

Engineering bill of materials (EBOM)

Created by engineers, this bill of materials deals with how a product is designed. This will include all the accurate materials and quantities to help manufacturers make better purchasing decisions for a quality-made product.

Manufacturing bill of materials (MBOM)

All components for manufacturing a complete product are included in an MBOM which lists part number, description and quantity. In addition to the material listing, you will find the tools and equipment required for the assembly and sub-assembly of consumables.

Sales bill of materials (SBOM)

This is where the finished product is managed as a sales item (as opposed to a stock item) and is represented at the process’s sales stage. Both the finished product and components will be included in the sales order document.

Service BOM

A service BOM is developed by engineers in the design phase and includes the parts, installation steps and repair instructions used by technicians when installing or servicing a product onsite.

Configurable bill of materials (CBOM)

This BOM is used by industries with highly configured products and it reduces the effort required to maintain product forms. The CBOM is created dependent in a modular BOM structure so that you can create customised versions of the products sold.

Assembly BOM

Similar to a sales BOM, the assembly BOM lists the parent item as the sales item and not the inventory item. However, only the finished product appears in the sales document.

Production BOM

This lists the components and sub-assemblies of a finished product including the descriptions, quantities, units of measurement and prices. A fully automated BOM system can be added to work orders so that all the raw materials are allocated correctly.

FAQ3: What are BOM levels?

There are also two tiers that are used to create a bill of materials, depending on the need. These are:

Single-level BOM

This is the simplest form that will show the assembly or sub-assembly and the required quantities of each. However, there is no indication of the relationship between the assemblies and sub-assemblies, with no part identification linked to repair or failure.

Multi-level BOM

Also known as an indented bill of materials, this details how you build your product including sub-assembly, components and all the required materials. Unlike the single-level BOM, this one has a hierarchical structure that outlines the components and sub-assemblies for each product.

It will include the finished product on top, working down into the various components that make up the product. You’re likely to find the multi-level BOM in manufacturing where several components are used to make a single unit.

FAQ4: Who prepares a Bill of Materials?

The bill of materials is a complex item that will require input from a cross-section of the company. This includes design, engineering, purchasing, material management and manufacturing.

FAQ5: What information is included in a BOM?

There is a significant amount of information required for the creation of an effective BOM, and the more comprehensive and accurate this information is, the better the process will be. Here is a look at some of the elements included in the BOM.

  • Level: This is the unique number that shows the level of a part of assembly within the BOM hierarchy, whether they are single-level or multi-level.
  • Raw material: The BOM should specify the quality or type of raw material that is used in the manufacturing process to create the finished product.
  • Part details: Included in the BOM is the unique number, name and description of all parts used to create a product. This allows you to identify and reference parts quickly, which is helpful for repairs and replacements.
  • Quantity: The number of individual parts to be procured or manufactured is specified for each assembly. This is an important feature of BOM.
  • Unit of measurement: This is defined in the BOM and can vary from kilogrammes and tons to centimetres and inches.
  • Description: The BOM includes a useful description of each part to help distinguish it from similar parts and make for quick reference.
  • Procurement method: The BOM will include the procurement method to identify whether the part or inventory is purchased externally or manufactured internally.
  • Notes: Your BOM will also include notes that provide any additional relevant information beyond the description of parts.
  • Images: Diagrams and other graphics of the product can be included to provide a visual representation of each component. This makes referencing much easier, minimises confusion and reduces risk.

FAQ6: How do you create a BOM?

Now that you have a solid foundation in a bill of materials, what they’re used for and what they do, you’re ready to start creating your own, accurate BOM. Here are the steps to follow:

Step 1: Data decisions

You need to decide what data is to be included in the BOM, and whether it will extend to consumables such as glue or wire? This will assist in securing all the materials for manufacture.

Step 2: Level type

You will need to choose the BOM presentation, whether single- or multi-level, that works for your industry.

Step 3: Centralise processes

While BOM relies on collaboration between departments and organisations, it’s important to centralise and configure it into a single record that is using the latest data available.

Step 4: Editing powers

With so much access to the BOM, you need to decide who has access to editing the information. Decide this early; if you have too many editors, the likelihood of errors can increase.

Step 5: Track revisions

As new information becomes available, BOMs are constantly updated. So, it’s important to track all changes in real-time and ensure it’s evident who edited what.

Step 6: List items

Now you can start listing the materials and components that make up the product which will keep adapting over time.

The simplest way to get through these steps and ensure your BOM is created effectively and accurately is by working with the latest BOM software.

Contact Omni today to find the best BOM software for your organisation.