Marketing to Engineers: What are Form Fit and Function models?

What are Form Fit and Function Models

Every manufacturers is beset with a dilemma: how to make it easy for potential customers to try out your parts without “revealing the secret recipe.”

We’ve found that a solution can be found in something called a Form Fit and Function model.

The three F’s

In general, form, fit, and function (FFF) refers to various characteristics of manufacturing parts. Each defines a specific aspect of the part to make it easier for engineers to match parts to needs.

The three characteristics are defined in the following ways:

  • Form – The shape and appearance of a part, including its weight, size, color, density, and dimensions. For example, a coupler may be 6.1 mm long, with a 2.3 mm diameter and a silver sheen.
  • Fit – The relationship or orientation of a part to another. Screws and cylinders, for example, must adhere to the dimensions of the holes through which they are meant to slide. The size of the hole itself is also a description of the surrounding object’s fit.
  • Function – Most simply, what a given part is meant to do. A part’s function follows the purpose of its design to a final role or action, such as holding other components together or shielding them from wear and tear.

Form Fit and Function models:

The definitions above describe what three FFF represent on their own. But the object of our discussion is the form, fit, and function model, which includes in its definition a very important subject for manufacturers: intellectual property.

Form, fit, and function models are exact representations of models with all of the intellectual property removed. This stripping of intellectual property does several positive things for the distribution process between manufacturers and design engineers.

  1. It creates a smaller model that engineers can test more easily
  2. It protects the manufacturing company so others cannot copy their designs

Form, fit, and function models offered in this way are only available through certain digital part catalog suppliers systems. The right software protects your ingenuity while still allowing for full testing by the engineers to whom you are marketing.

Form, fit, and function models include “mates and constraints.” CAD constraints establish the orientation of various entities in a part or system; they are also referred to as “mates.” Since FFF models include appropriate constraints, they move and mount just like the real thing should!

3D Visualization within Product Configurator:

You can see with the Parker-Origa gearbox below the product can be easily previewed within the product page before ultimately downloading.

Why Engineers need Form Fit and Function models

Many MFG companies become very concerned by the thought of sharing their product models or designs. In a sense, they’re right to feel this way.

It’s a bad idea for manufacturers to take their actual engineering drawings and post them on their website for anyone to use. This shares their intellectual property with the world.

A better way is to have a digital part catalog provider create form, fit, and function models. Engineers can then use these “hollow” parts exactly like a real engineering drawing, except with the vital intellectual property safely removed, as seen below with the same Parker-Origa gearbox as above. The external dimensions and fitment data are intact, with none of the internal components to protect the valuable IP.

The World Intellectual Property Organization defines “intellectual property” as “creations of the mind: inventions, literary and artistic works, and symbols, names, images and designs used in commerce. IP is divided into two categories: industrial property, which includes patents, trademarks, industrial designs and geographical indications of source; and copyright, which includes literary and artistic works such as novels, poems and plays, films, musical works, artistic works such as drawings, paintings, photographs and sculptures, and architectural designs.”

Your entire engineering drawings fall under the category of industrial property. So too does anything created by engineers who buy your parts. Therefore, both of you have a vested interest in the protection of your designs.

The solution, as an article on the American Machinist site shares, is to “adopt ‘intellectual property friendly’ approaches to collaboration including sharing only the amount of design data required by partners to accomplish their tasks.” That is exactly what a form, fit, and function model, presented by a credible software platform, allows you to do.


FFF models check every box for industrial marketers: they provide easy and accurate testing for engineers who are looking into your parts catalog, and they help you rest assured that the industrial creativity you’ve spent so much time and effort on isn’t stolen and discredited.

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