Bill of Materials (BOM)

An extensive list of raw materials, components required to manufacture or repair a product or service is called “bill of materials (BOM)”. A bill of materials often is designed in a format which keeps the finished product at the highest level and the other individual components and materials at the bottom. When it comes to businesses that involve engineering used in the design process, there are different bills of materials used for the same.

BOM - Breaking it down further

BOM is the complete list of all the items that are required to manufacture a product. A BOM is sometimes also referred to as the structure of the product or assembly component list.

The structure of a bill of materials depends on business needs and project requirements. Take, for example, the manufacturer of a bicycle wants to build 1000 bicycles. A bill of materials for a bicycle will involve all the necessary parts like seats, brakes, frames, tires, chains, pedals, handle-bars, etc. including the quantities required of each component along with their prices.

A well-structured ‘bill of materials’ helps companies with:

  • Plan purchases of raw materials
  • Estimate material costs
  • Gain inventory control
  • Track and plan material requirements
  • Maintain accurate records
  • Ensure supply robustness and reduce waste

The most common methods of representing a BOM are the following:

Single-level bill of materials

Here, the list of products is comparatively simpler. Though being simple, this type of BOM is mostly not preferred for complex products as is not stable enough to specify the relationships between the parent and child parts or between assemblies or sub-assemblies. If at all there is any failure caused in the product, the assembly manager can never make out which part needs to replaced or repaired.

Multi-level bill of materials

This type of BOM takes more time compared to single-level BOM but offers reliability and finer details on the parent and child parts of the product. Also, this type of BOM is made in a way that shows the entire relationship between the parent and child part.

Since the BOM involves everything that is concerned with the product that is being manufactured, it can anytime be used beyond manufacturing purposes, such as engineering, design, sales, material management, etc.

Types of BOMs

#1 Manufacturing bill of materials

This type of BOM (MBOM) includes a well-structured list of all the parts or items required to manufacture a complete product. The information present in the MBOM is shared with all the teams that are involved in the ordering and building of the product, from top to bottom.

#2 Engineering bill of materials

This type of BOM (EBOM) is all about the parts that are designed by the engineering department. The EBOM will consist of a mechanical or technical drawing of a finished product. It is common to have more than one EBOM for a product as the design has to necessarily undergo a series of moderations.

#3 Sales bill of materials

This type of BOM (SBOM) defines the product when in the sales stage. This means that the details of the product prior to its assembly are provided in the SBOM. Here, the finished item is treated as a sales product and not an inventory item.

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