[Editor’s note: In a recent post, Dave Martin made the case for designing for reuse. He urged product developers to create models in such a way that they can be easily modified in future revisions. “Engineers, designers, and managers often make decisions that prevent data from being leveraged in the future,” Martin wrote. But with a little forethought and extra effort, they can save time and costs in future revisions.

His tips for creating more reusable designs included following design intent, minimizing external references, and complementing parametric modeling with direct modeling. Now he’s adding two more to the list for those who want to get even more out of design reuse.]

Use Native Surfacing Tools

Imported data is more difficult to reuse, because it cannot be changed as easily or quickly as native geometry. When designing your model’s overall shape, CAD packages can offer three paradigms for surface creation:

• Technical, or parametric, surfacing. This method works great when you want to control specific sections, boundaries, and trajectories, especially with dimensions that you can modify.
• Style surfacing. Design and manipulate curves and surfaces by dragging them dynamically in three-dimensional space. This method is more artistic, providing the user with the ability to design more by “feel” than with traditional parametric features. Style surfaces provide greater ability to create Class A surfaces, including G2 and G3 continuity.
• Subdivisional modeling. This resembles a clay sculpting technique. Start with a basic shape, and then push and pull different portions in different directions to generate and refine your shape.

A Creo Freestyle model of a vehicle’s shape.

These various paradigms can be used together. Parametric curves can be used as inputs to style surfaces, and style curves can be used to generate parametric surfaces. Dimensional controls can be created in style geometry so that it can be modified just like standard parametric features. Parametric surface editing tools can be used to manipulate freestyle surfaces created by subdivisional modeling.

Native surface geometry increases both design intent – the capacity to react to changes – and design reuse.

Part Naming

If you can’t find your data, you can’t reuse it. The main cause of data not being searchable is improper naming, which leads to part proliferation, making your parts even harder to find. Improper part naming happens in a variety of ways, including:

• Acronyms and abbreviations. For example, you’re searching for “screw” when someone has named it “SHCS” (for socket head cap screw).
• Misspelling. It’s hard to find a model when it’s been misspelled. How would you locate a shield spelled SHEILD, an antenna spelled ANTENA, a gimbal spelled GIMBLE, or a receiver spelled RECIEVER?
• Not filling in the Common Name field, so the name and common name end up being the same value.

When people can’t find parts, they make new ones. This results in part proliferation, and the more parts you have in your database, the harder it is to find the ones you actually want to reuse.

The solutions to improper part naming and part proliferation include:

• Adopt and enforce a standard naming convention. Make sure users provide a common name that describes the part and is different from the Name (i.e., the part’s number).
• Ensure your model templates have the appropriate parameters to identify their type and critical characteristics.
• If you are using Windchill as your CAD data management tool, make sure that the CAD model parameters are designated to corresponding Windchill attributes.
• Construct an easily searchable and browsable library of standard parts and COTS (Commercial off the Shelf) components.

Conclusions

If your organization suffers from not being able to leverage existing designs to create new ones, with a little effort you can turn that around. By reusing existing data instead of creating new data from scratch, your design organization will increase its efficiency and accelerate product development cycles.

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