A to B Surfacing in Automotive Design: Why It Matters
- 3132BHAVANA MARAMREDDY
- 6 days ago
- 3 min read
Updated: 3 days ago
Table of Contents
Introduction
In automotive product design, creating parts that are both functional and manufacturable is key. One essential step in this process is called A to B surfacing. It’s not just about turning a design into a 3D model—it’s about turning an idea into something that can actually be produced and used in real vehicles.
What is A to B Surfacing in Automotive Design?
Once designers finalize the A surface—the visible, aesthetic side of a component—it's time to give the part real thickness. This is done through A to B surfacing.
A Surface: The outermost surface, often styled and shaped for appearance.
B Surface: An offset of the A surface, created at a distance equal to the part's desired thickness.
The space between A and B surfaces is then enclosed to form a solid model.
The Steps of A to B Surfacing
Start with the A Surface – This is the surface with no thickness, just a styled form.
Offset the A Surface to create the B Surface – This is where you define the part’s actual thickness.
Add Engineering Features – Bosses, ribs, snaps, and mounting features are added to the B surface.
Close the Volume – Side surfaces are added to connect A and B, forming a closed boundary.
Solidify the Model – The final enclosed surface is converted into a solid body ready for tooling.
Why Not Use the “Thicken” Command?
Most CAD software includes a “Thicken” or “Thick Surface” command, which appears to do the same thing—add thickness to a surface to create a solid. However, it often fails in real-world applications. Here's why:
Key Reasons for Using A to B Surfacing
1. Curvature Issues
When an A surface has sharp curves or small radii, applying a uniform thickness may cause the surfaces to self-intersect. The thickening operation will fail and won’t generate a solid body.
2. Variable Thickness
Automotive parts often require variable wall thickness—thicker in stress zones and thinner in light-load areas. The thickening command only supports uniform thickness, which limits the designer’s flexibility.
3. Draft Angle Management
Manufactured parts must include draft angles to allow for easy removal from molds. The “Thicken” command does not account for draft, leading to parts that cannot be ejected from the mold cleanly. A to B surfacing allows designers to include these draft angles manually.
Conclusion
A to B surfacing may seem like a long process, but it’s critical for creating parts that are aesthetically accurate, structurally sound, and manufacturable. By offsetting the A surface to create a B surface, adding draft angles, and handling variable thicknesses, engineers ensure that their designs can move smoothly from CAD to production.
If you’re serious about automotive design, understanding and applying A to B surfacing is not optional—it’s essential.
Comments