Don't Care About Design Intent? You Should

Written by: Dave Martin

Change is an inevitable fact of the product development process. Requirements change, the market changes, and technology changes; all this results in the need to make engineering changes to our product definition and documentation.

Implementing engineering changes can be expensive and time-consuming when part and assembly models have to be scrapped and started over from scratch. But this doesn’t have to be the case when your models are built with the correct strategy.

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Unfortunately, many end users and projects approach their 3D CAD package with the goal to build the models as quickly and easily as possible. But that approach doesn’t take into account the entire lifecycle of your models or product. A typical product lifecycle looks something like this:

 Product life cycle graph

The typical product lifecycle may extend for decades

Above the time axis, we see the four major stages through which a product progresses through its lifecycle. Below the time axis, we see lifecycle states that define the evolution of our engineering data.

As we can see, the initial concept phase is a very brief and relatively short portion of the lifecycle. The time spent building parts and assemblies during this concept phase may be days, weeks, or months. But the entire lifecycle for a product can last years or even decades. We should be basing our 3D CAD strategy around the entire lifecycle, not the beginning of it.

Furthermore, as time goes on, the cost of those changes increases:


Cost of design change over time

Given that designers and engineers spend most of a product’s lifecycle changing and modifying models, and the costs of those changes increase with time, our 3D CAD modeling strategy and goals should reflect that. Your 3D CAD tools and processes should be geared toward implementing changes, not initial creation.

Building Future-Friendly Models

This is where Design Intent comes in. Since the initial concept phase is only a small portion of the lifecycle of a product, and we spend the majority of our time modifying and updating our models, we want to build additional intelligence and information into our models. This additional information and intelligence is focused around:

  • Geometry: the shape of our products and parts, and how they interconnect.
  • Dimensions and parameters.
  • The relationships between different features and components, and how changes should be propagated between them.

Then when we modify our models, they update in ways that we planned for and expect. This is Design Intent, and it helps you create models that are:

  • Flexible: our models contain the right dimensions, parameters, features, and components, so that we’re able to modify them instead of starting over.
  • Parametric: when we make changes, the changes are propagated to other features and components.
  • Robust: we can update our models without causing regeneration failures that we have to fix.

Design Intent and Creo

Design Intent drives the core philosophy around which Creo Parametric is based. When we focus on Design Intent, we reduce the cost of change and we get to market faster by being able to change our models quickly and easily. And with lower frustration and more time to spend engineering instead of fixing or recreating, we have happier design teams.

In future blog posts, we’ll explain how to build Design Intent into your models at the sketch, part, and assembly levels. Stay tuned!

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Tags: CAD

About the Author

Dave Martin

Dave Martin is a Creo, Windchill, and PTC Mathcad instructor and consultant. He is the author of the books “Top Down Design in Creo Parametric,” “Design Intent in Creo Parametric,” and “Configuring Creo Parametric,” all available at He can be reached at

Dave currently works as the configuration manager for Elroy Air, which develops autonomous aerial vehicles for middle-mile delivery. Previous employers include Blue Origin, Amazon Prime Air, Amazon Lab126, and PTC. He holds a degree in Mechanical Engineering from MIT and is a former armor officer in the United States Army Reserves.