Interchangeability, Revisions, and New Part Number

My last week’s article about FFF (Form. Fit and Function), triggered many interesting discussions online and offline. Thank you all for coming back to me and sharing your insight and experience. Today, I want to continue the conversation and talk about another question, I’ve been asked very often – creating a new Revision to the existing Part Number or introducing a new Part Number.

The problem?

One of my favs of Albert Einstein is related to the problem-solving approach – “If I had an hour to solve a problem I’d spend 55 minutes thinking about the problem and five minutes thinking about solutions”. So, I want to start with the problems of managing part numbers and introducing ECOs. What I always want to start is by asking about the cost of ECO in each organization and how many ECOs the organization is proceeding with every week or month. It will give you an idea about the possible scale of the problem and what you can achieve by optimizing the process related to interchangeability and Part Numbers/Revisions.

In a nutshell, this is a summary of the problem:

• Each new Part Number introduction cost $$$
• Each ECO cost $$$

The cost of management is, in addition, to actually work that needs to be done and includes documentation, updates of models, and documentation. The cost goes down in a variety of additional costs such as a scrap of existing parts and many others.

Change Process and Blind Man Rule

My favorite definition of interchangeability can be defined as a blind man rule. I heard it a long time ago, it makes total sense and it is very easy to adopt. Think about an item with a part number as a piece you can put in a bin and then asking a blind man to pick up the part for you. If a blind man can select a part from the bin with a specific part number without making any additional checks, these parts are completely interchangeable and you don’t need to scrap them when you introduce a change to the design or anything else. Otherwise, they are not.

Revision vs New Part Number

Once you design and make a part (or assembly) it has a Part Number. This is a simple rule. What will happen with this part in the future, might require a new part number or a new revision. How to decide. A simple rule I’ve seen in many places is based on the need to separate between these two parts with the change implemented. This means you cannot put them in the same bin and you need to trace them back to the previous Part Number. If all that I said before is needed, create a new Part Number, otherwise, just make a revision.

Superseding and Traceability

The superseding process describes the process where one item needs to be replaced by another one and to provide traceability between usages of these part numbers.

What is my conclusion?

One of the main goals for company configuration management policies is to define a set of rules for identification and change management. The fundamentals of identification include part number, revision interchangeability, and the change process rules to define a new revision or to create a new part number. Just my thoughts…

Best, Oleg

Disclaimer: I’m co-founder and CEO of OpenBOM developing a digital network-based platform that manages product data and connects manufacturers and their supply chain networks. My opinion can be unintentionally biased.