All about ‘Class -A’ Surfaces

Today’s products are not only designed considering their functionality but special consideration is given to their form and aesthetics which is crucial in the perception and reality of a quality product to the consumer. Class A surface refers to those surfaces which are VISIBLE and abide by the physical meaning, of a product. This classification is primarily used in the automotive and increasingly in consumer goods (toothbrushes, PalmPCs, mobile phones, washing machines, toilet lids, etc.). It is a requirement where aesthetics has a significant contribution. For this reason, the exterior of automobiles is deemed Class-A, while the body in white (BIW) components are ‘NOT Class-A’.

What is the class-A surface?

Class ‘A’ surfaces are primarily used in the automotive environment and refer to those surfaces which are visible in a product. In other words: A - class surfaces are those aesthetic/free-form surfaces, which are visible to us (interior/exterior), and have an optimal aesthetic shape and high surface quality.

Here, one should understand the difference between the internal or external and visible or hidden surface. The surfaces or regions which are visible nowadays are considered for Class-A modelling. It is one of the reasons why the importance of Class-A modelling is increasing day by day. Majority of the time this term is used in Plastic Part designs. 

Quality Requirements for Class-A surfaces

The baseline requirements for Class-A are the same for production-quality surfacing in all industries to build tight tolerances for G0, G1, and G2 continuity. It's important to note that there are no absolute rules for tolerances or continuity levels. A skilled Class A modeller should be able to judge which settings will result in the right quality for car production. It is highly required that surfaces created as a Class-A should have curvature continuity i.e. the continuity between the surfaces sharing the same boundary. To know more about Curvature Continuity you can go through our detailed article on surface continuities and their types. Class-A aesthetic quality is generally understood as being 'perfect' highlight reflections. G3 Continuity across the surface patches is often used to achieve this.

Class-A surfaces should not have ribs, snaps, or bosses present in them. 

Wondering how to create Class-A surfaces?

Below are the CAD platforms where we can create class-A surfaces:

1] Autodesk Alias 

2] ICEM Surf

3] FreeStyle Module in CATIA by Dassault Systems

5] Imageware and Unigraphics Class A module