What is the difference between CAS surface and A surface?
3 Answers
Here is an introduction to the differences between CAS surface and A surface: The sequence is different: In automotive styling, the A surface comes first, followed by the CAS surface. Before the release of the automotive styling A surface, the digital model used for preliminary display of the interior and exterior styling is called the CAS surface. The content they represent is different: The A surface must meet the requirements of a gap between adjacent surfaces of less than 0.005mm, a tangent change of less than 0.16 degrees, and a curvature change of less than 0.005 degrees. On the other hand, the CAS surface is mainly used in the styling feasibility study phase for checking regulatory requirements, styling, engineering, production, after-sales maintenance, insurance services, and the production of small-scale clay models.
I've been in the automotive design circle for many years and have a clear understanding of the difference between CAS surfaces and Class-A surfaces. CAS surfaces are the digital model surfaces we create using computer-aided styling software, mainly used for visualization and evaluation in the early design stages, such as simulating body lines and wind tunnel testing. They are relatively rough, allowing designers to quickly modify shapes or add details. But Class-A surfaces are different – they are high-quality surfaces that have undergone multiple optimizations for actual production, requiring seamless smoothness and compliance with manufacturing standards to avoid any flaws affecting the final product. Simply put, CAS surfaces are the sketch phase, while Class-A surfaces are the finished version. This transformation process saves significant costs and time, avoiding rework issues in production. In practical work, I often see teams starting with CAS surfaces and gradually transitioning to Class-A surfaces, ensuring every vehicle's exterior is both aesthetically pleasing and durable.
As a veteran working in an automobile factory, I've dealt with numerous Class-A surface issues. Class-A surfaces are the final high-quality surfaces on a car body, such as door panels or hoods, which must be defect-free to ensure proper paint application and resistance to deformation. In contrast, CAS surfaces are merely virtual surfaces on computer screens, used by designers for styling simulations and rendering, without real-world validation. The difference lies in: CAS surfaces allow for quick adjustments and iterations, while Class-A surfaces directly impact user experience and durability. If there's an issue with a CAS surface, we can easily modify it in the design studio; but if a Class-A surface has problems, the entire production line might come to a halt. This process affects cost control and production efficiency, and I believe the automotive industry's progress largely benefits from such clear distinctions.
