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# An Introduction to SOLIDWORKS Surface Modeling

Tying into the theme of the 6W tags used for file filtering on the 3DExperience Platform, let’s dive into the 6W’s of SOLIDWORKS surface modeling as it pertains to traditional SOLIDWORKS. We’ll begin by covering WHAT is surfacing or how it may be defined, then transition into HOW it works. Then we will relay WHERE to find surfacing tools and WHO might benefit from them. Lastly, we’ll cover WHEN is most applicable to use surfacing and WHY it’s essential to take that next step in your modeling endeavors.

## WHAT is Surface Modeling?

Rather, what is a solid? Technically speaking, every edge on a solid body is shared between two faces. Even more specifically, this can be proven by Euler’s Formula and a simple cube. For a solid body to be solid geometry, Euler’s applied formula for a cube must equal a value of 2 where 8 vertices minus 12 edges plus 6 faces equals a value of 2. Success! We have a solid cube.

But what looks like a solid in CAD might not be a solid. Below is an image of two identical models in SOLIDWORKS. The cylinder on the left is a solid body and the similarly-looking cylinder on the right is a surface body.

Generally speaking, if a model can be created in CAD using solid modeling features like a simple boss extrude, then use the solid modeling features to save yourself some time. The part environment on the right displays a feature manager design tree with many more features than its solid body counterpart. This is because the steps in the surface modeling process are individualized. Solid body modeling actually speeds up this process for us.

## HOW does Surfacing work?

While most solid body faces in CAD are broken down into a mesh of curves, these curves are typically lines, arcs, and sometimes circles. Model faces are typically trimmed from an originally four-sided surface.

Surfaces, however, are broken down into a mesh of splines (commonly referred to as NURBS or ‘Non-Uniform rational b-spline’ Surfaces) to achieve more complex geometry. Surfaces do not follow the same rules as solids. Some may have less than four sides. In cases where a surface has less than four sides, singularities can occur when curves converge on a vertex, which can cause problems later in the design process with fillets, shells, and offsets.

## WHERE to find Surfacing in SOLIDWORKS

Surfacing capabilities also exist on the 3DExperience Platform. The 3D Creator Role includes the xDesign app which has surfacing tools. Additionally, the 3D Sculptor Role contains the xShape app for non-analytical geometry. I mention this because often at times, surfacing techniques are used to achieve non-uniform geometry. The xShape app has push-pull capabilities which generate these shapes by non-traditional modeling methods relative to SOLIDWORKS 3D CAD.

## WHO is Surface Modeling for?

Surface modeling can be somewhat of a niche market as surfacing tools certainly aren’t standard or traditional CAD tools. But more industries than you may think are utilizing these advanced capabilities. To name a few, Industrial Design and Consumer Products are areas within the design industry where you might expect to see CAD users accessing these design tools. Inject Molded Components use surfacing as well as CAM users. If an appliance is sitting on your kitchen countertop, it was most likely modeled using surfacing tools. Medical products are another large area of surface tool usage.

## WHEN to use Surfacing

Surfacing is often required for non-analytical geometry, i.e. creating anything that would otherwise be a challenge to design with standard solid body modeling tools. Any household or office item that is ergonomic would likely require surfacing tools to achieve the necessary curvature.

Another situation that may call for surfacing tools would certainly be repairing faulty faces from imported geometry.

Reference surfaces can also be used in a more advanced modeling technique for end conditions. If an “up to surface” end condition is used, then the end face of the extrusion will conform to the selected surface rather than maintaining its original two-dimensional profile.

Yet another creative use for surface tools in SOLIDWORKS is with master modeling techniques involving a multibody offset design. Below is an example used in the CATI surface modeling class in the design and control of a speaker and baffle model.

By this method, a series of surface bodies in the parent file drives the child parts which correlate to the resulting assembly file in a trickle-down effect of associativity. Master modeling is a one-way street so changes to child parts cannot affect the original files.

## WHY is Surfacing important?

Some product designs require advanced design capabilities. To access those features, you’ll need a SOLIDWORKS Premium license.

You are certainly in good hands in your surface modeling endeavors as many application engineers are certified in surfacing with the CSWPA-SU certification.

SOLIDWORKS surface modeling training is also available virtually as well as in-house.

Lastly, here are a few related blogs that I think you should check:

SOLIDWORKS – Choosing the Right Surface Patching Tool

Gabriel Rodriguez
Application Engineer II
Computer Aided Technology