Creating a Bill of Materials

7/27/2019 Creating a Bill of Materials

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Creating a Bill of Materials

Creating a Bill of MaterialsAll manufacturers building products, regardless of their

industry, get started by creating a bill of materials (BOM).

The BOM, which is essentially a comprehensive list of parts,

items, assemblies and sub-assemblies, can be understood

as the recipe and shopping list for creating a final product.

A BOM explains what to buy, how to buy and where to buy,and includes instructions for how to assemble the product.

Because the bill of materials pulls together all sorts of

product information, it is common that several disciplines


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(design and engineering, document control, operations,

manufacturing, purchasing, contract manufacturers and

more) will consume data contained within the BOM record to

get the job done right. The BOM guides positive results

from business activities like parts sourcing, outsourcing and

manufacturing, so it is important to create a BOM that is

well organized, correct and up-to-date.

And for companies that outsource manufacturing activities,

it is especially important to create an accurate and revision-

controlled bill of materials. Any time the BOM is handed off

to a contract manufacturer (CM) or supplier, it should be

correct and completeotherwise you can expect production

delays.

What to include in an effective bill of materialsBecause one of the main functions of the BOM is to ensure

that the product is built right, it is best to include specific

pieces of product data in the BOM record. Whether you are

creating your first bill of materials or are looking for ways to

improve how you create a bill of materials, here is a high

level list of information to include in your BOM record:

BOM LevelAssign each part or assembly a number todetail where it fits in the hierarchy of the BOM. This allows

anyone with an understanding of the BOM structure to


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quickly decipher the BOM.

Part NumberAssign a part number to each part orassembly in order to reference and identify parts quickly. It

is common for manufacturers to choose either anintelligent

or non-intelligent part numbering scheme. Whichever

scheme you use, make sure you avoid creating multiple part

numbers for the same part.

Part NameRecord the unique name of each part orassembly. This will help you identify parts more easily.

PhaseRecord what stage each part is at in its lifecycle. Forparts in production, it is common to use a term like In

Production to indicate the stage of the part. New parts that

have not yet been approved can be classified as 'Unreleased'

or 'In Design'. This is helpful during new product

introduction (NPI) because it allows you to easily track

progress and create realistic project timelines.

DescriptionProvide a detailed description of each part thatwill help you and others distinguish between similar parts

and identify specific parts more easily.
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QuantityRecord the number of parts to be used in eachassembly or subassembly to help guide purchasing and

manufacturing decisions and activities.

Unit of MeasureClassify the measurement in which a partwill be used or purchased. It is common to use each, but

standard measures like inches, feet, ounces and drops are

also suitable classifications. Be consistent across all similar

part types because the information will help make sure the

right quantities are procured and delivered to the

production line.

Procurement TypeDocument how each part is purchasedor made (i.e. off-the-shelf or made-to-specification) to

create efficiencies in manufacturing, planning and

procurement activities.

Reference DesignatorsIf your product contains printedcircuit board assemblies (PCBAs), you should include

reference designators that detail where the part fits on the

board in your BOM. Capturing this information in the BOM

can save time and help you avoid confusion down the road.

BOM NotesCapture other relevant notes to keep everyonewho interacts with your BOM on the same page.


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Documenting all this information in your BOM will keep

business activities and manufacturing tasks on target. In

addition to capturing this information, you should also

consider the following questions when creating a bill of

materials.

4 key questions you must answer beforecreating a bill of materials

1.Will you document consumables in your BOM record?Many manufacturers second-guess the decision to include

glue, wires, fasteners and other non-modeled parts like

labels and boxes in their BOM record. But if the part does

not make it into your BOM, it might not make it into your

product. So take the time to document these parts.

2.How will you attach files to your BOM record?As you create your BOM, keep records of supporting

documentation like CAD drawings, part datasheets and

work instructions. It is best to also associate these files with

their specific BOM level items.

3.Who is going to use the BOM record?It is important to include as many details as possible in your

BOM. You may never interact face-to-face with some of the

people utilizing your BOM, so it should convey all the

information they might need throughout the products


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lifecycle.

4.How will you reconcile your BOM record?Your BOM record may go through several iterations during

the design phase, so you should have a way to distinguish

between multiple BOM record versions. That way, when it is

time for production, you can be sure each person who uses

your BOM is consulting the correct version.

An accurate BOM supports efficientmanufacturing processesCreating a bill of materials is not only a necessary step in

the product development process, it is also what makes

your product design a reality. Before you create a BOM

record, it is important to consider who will utilize the

information and how you will maintain and manage all

associated product documentation like part datasheets and

CAD files. Develop more efficient manufacturing practices

by capturing detailed part information when creating a bill

of materials.

Documents

Creating a Bill of Materials