Form, Fit, and Function

“Form, fit, and function” are most commonly discussed in relation to the design of an object, or when considering if a process is value added or not.

• Form: Form is the physical characteristics of the product. It includes things like shape, weight, color, material, etc.
• Fit: Fit is short for “fits intended application”. Alternatively, it may also reference whether the physical dimensions of a part fit into the product it was designed to go into.
• Function: Function is what the product actually does.

Engineers pay close attention to the form, fit, and function of a design, whether during its initial inception, or when changes happen throughout the product’s life cycle.

Companies with a strong continuous improvement culture tend to have more product design changes than others, as each person in the company tends to assume some of the roles traditionally filled by manufacturing engineers. Specifically, they make frequent recommendations for product and process changes to make production flow better.

Think like an engineer when making changes. Look at how a new design will affect form, fit, and function, and consider what those changes will mean to the customer. As a rule, even if a change makes a production process easier, it can’t change the perception of the 3Fs in the customer’s eyes.

For example, if you make washing machines, it might be easier and cheaper to weld the cover into position. But that would make repairs down the road much more expensive and difficult for the typical do-it-yourselfer. The fit of the product into the needs of the owner, specifically low lifetime cost of ownership, is reduced.

Form, fit, and function are also a good litmus test against which to check if a process step is value added or not. If a step changes the form, fit, or function of a product, it is probably value added. Tightening a bolt that holds parts together, or applying paint are both examples of steps that change form, fit, or function. A customer values the 3 Fs, so it follows that the step would be something the customer would be willing to pay for.

But if the step does not change the 3Fs, it is likely non-value added. It may still be necessary (i.e. moving parts from the receiving dock to the production areas), but still is not something the customer would like to see on an invoice.