Engineering Bill of Material: The Ins and Outs

What is an Engineering Bill of Materials (EBOM)?

The engineering bill of materials (EBOM) is a special type of bill of material which defines the product as designed. It contains the list of items, parts, components, sub-assemblies and assemblies in the product designed by engineering.

The engineering BOM is often organized by engineers based on the Computer-Aided Design (CAD) or Electronic Design Automation (EDA) tools used. And for any given product design more than one EBOM may be created. For example, the BOM for the Printed Circuit Board Assembly (PCBA) designed by an electric engineer lists the resistors, capacitors and chips. The BOM for the product as designed by a mechanical engineer includes custom parts and purchased hardware like an lcd, buttons and screws.

While multiple engineering BOMs may exist, the EBOM is not the only type of bill of material. The engineering bill of materials (EBOM) deals with how a product is designed, while the manufacturing BOM or MBOM details what is needed to assemble a product and differs from the EBOM in both structure and depth.

How an engineering BOM helps

Manufacturing a product is often compared to that of a recipe. If you miss an ingredient or step in the baking process the outcome will likely be a complete failure. With an engineering BOM, missing a part or component will negatively impact manufacturing the product without any hiccups. Because the information captured in an EBOM is handed-off to manufacturing, the completeness - or lack thereof - could influence the product quality.

Three reasons a complete and accurate EBOM supports manufacturing and company success

Capturing the right level of detail in an engineering BOM can prepare the company for success and prevent needless extra work for engineering, manufacturing, sourcing and purchasing in the long run. A complete and accurate engineering BOM can better prepare manufacturing for production runs and supports the new product introduction (NPI) process along the way.

Here’s three reasons to document the details:

  1. Got good parts?

    It is good manufacturing practice to verify first article parts coming off a new tool. With a comprehensive bill of materials, manufacturing will have adequate information to ramp tools for new parts and time to test parts before production fully ramps.

  2. Best lead time and pricing.

    Give manufacturing the right parts and right quantities and they are armed with the information to make better purchasing decisions. They can negotiate with multiple vendors to obtain the most competitive pricing. Getting them the information early in the process also ensures that parts with long lead times are ordered and delivered when they need to be without expedite charges.

  3. Prevent extra revision cycles and work.

    The manufacturing department must operate with efficient processes and if they’re handed the correct and complete details on the parts, items and components they won’t be left second guessing. With the right level of detail in the EBOM, extra and unnecessary changes in the manufacturing process can be avoided.

Three setbacks of an incorrect and incomplete engineering BOM

Manufacturing product with wrong information in an engineering BOM can set you back and cause problems down the line. Here’s three setbacks of a wrong and incomplete EBOM

  1. Build problems.

    If the number of parts or components isn’t correctly listed in an EBOM, for example 10 screws are documented but your product requires 12, purchasing will not have the information to buy the right quantity. With too little inventory of even just one part missing, builds will be stopped or prevented from starting.

  2. Time and money down the drain.

    A wrong part captured on the EBOM can mean money wasted on unusable inventory or a build delay while the correct part is on order.

  3. Out of control revision cycles.

    In order to get the product built and out the door, a smooth hand-off from engineering to manufacturing nust happen. Extra and unnecessary change cycles will ensue if an EBOM is not detailed or stable when transferred to manufacturing.

Engineering BOM — Why it’s best to get it right, right from the start

Engineers are often asked to release designs earlier and earlier even when they are not ready. They must work hard to pass the right and correct information to manufacturing so their design can become a reality. With a complete and accurate engineering bill of materials, the hand-off to manufacturing will be made much smoother. Manufacturing will be armed with the information to make better decisions, including pricing and lead time options, as well as manufacturing process and logistics choices. When all the details including parts, items, components and quantities are correctly noted in an EBOM disruptive late and last minute changes can be avoided.

Arena PLM helps manage and control EBOMs.

Arena PLM, cloud-based solutions for bill of material and change management, helps engineers and manufacturers better control their product data. All bill of materials (engineering BOMs and manufacturing BOMs) and product information is stored in a centralized location, allowing engineering and manufacturing to share critical product data more effectively. Arena PLM connects with CAD and EDA tools eliminating duplicate data entry and ensuring that your product information is always up to date.

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