Prototype Bill of Materials

A Bill of Materials or BOM in engineering is a complete accounting of every component of a manufactured product. It is a useful tool for managing the complete set of material requirements involved in fabricating a device.

By asking for a bill of materials, I am essentially asking for you to visualize your prototype in its entirety even if specific design details are still unresolved. You will need a clear idea of all functional components and structures in order to identify and name every part. This is essential early in the process since acquiring materials typically represents a significant scheduling bottleneck that frequently determines the critical path.

For our purposes, a bill of materials typically involves three categories:

  1. Fabricated parts, e.g. parts you will laser-cut or 3D print. These may conceivably involve special materials not available from Lending, e.g. fabric.

  2. Special components not available in the standard lab stock. These may require purchasing or are sometimes available from the private class inventory.

  3. Stock lab parts, including both electronics and mechanical. A product manufacturing BOM will include every last fastener, but for our purposes this can be simplified. E.g., it may be helpful to specify “M3x10 button screw” to remember which fastener is best for your DC motor, but it may be sufficient to note “1/4 inch shoulder screw and hardware” for a pivot rather than list every washer.

Objectives

After this exercise, you should be able to:

  1. Collaborate with a partner on concept development.

  2. Identify a critical path of engineering unknowns.

  3. Write a bill of materials.

Format and Fields

A Bill of Materials is generally presented in tabular format; a Google Sheet is recommended. A rough template is available as BOM-template.xlsx.

For all parts, please include:

  • short part name (meaningful within your design)

  • short part description (to understand form and function)

  • quantity per machine

For fabricated parts, please include:

  • material

  • process (e.g. laser-cut, 3D print, woodshop, sewing , etc.)

  • CAD file name

For purchased parts, please be sure to include each of the following fields:

  • Item Description

  • Vendor Part Number

  • Vendor

  • Purchase Link

  • Quantity to purchase

  • Cost per Item

Deliverables

Please prepare a detailed bill of materials and submit it as a Google Sheet for the assignment post. Please be sure to identify any special materials not available in the lab inventory. Please format your BOM as a table following the purchasing template linked above.