Introduction to the automotive design process using CATIA - Part 1

This is an introduction to the plastic design course using CATIA specific to the interior and exterior trims in an automobile offered by Skill-Lync. The content that will be covered are: 

  • Automotive Design Process understanding and where the Trims design helps in the Product Development Process.
  • Trims – Interior and Exterior.
  • Understand:
    • Class-A surfaces and tools that are used.
    • CAD software and their applications to Trims design.
      • Advantages of CATIA
  • Plastic Design – An overview
  • What this course is about, and what is the potential for it?


Understanding the Automotive Design Process 

On a broad spectrum, the automotive design process can be split up into four stages: 

  1. Concept
  2. Sketch
  3. Class A Surface (CAS)
  4. Computer-Aided Design (CAD)

An automotive vehicle concept is first hypothesized or envisioned by an artist, designer, or engineer, which is then sketched onto a paper. Once an idea is approved, it moves on to the computer where it is rendered in 2D.  

Then, the Class A Surfaces (CASs) are built. This is followed by a complete 3D CAD modelling of the automotive vehicle, including photorealistic renders, which later goes into mass production.  

On a higher level, the product development process can be summarized as follows: 

  1. Styling theme and approval CAS
  2. Preliminary design
  3. Preliminary analysis
  4. Final style approval
  5. Detail design
  6. Verification
  7. Development
  8. Prototype build
  9. Design validation
  10. Plot production
  11. Launch and mass production

This learning outcomes from this course will contribute to the following design processes: 

  • Styling theme and approval CAS
  • Preliminary design
  • Preliminary analysis
  • Detail design
image source


What Are Automotive Trims?

An automotive vehicle, like a passenger car, typically has two significant contributors to the design – Body in White (BIW) and Trims. 

Body in White (BIW) 

Body in White indicates the sheet metal or aluminium welded/integrated structure that holds all the other systems of an automotive vehicle. 


Trims refer to all the aesthetic and non-visible parts. They contribute about 30 per cent of an entire automotive product and exclude systems like engines and transmissions.  

Trims are of two types: 

  1. Interior Trims – Parts that can be seen inside the vehicles and are used for mounting instruments like an instrument panel or a dashboard.
  2. Exterior Trims – Parts that can be seen outside the vehicles like the front and rear bumpers of a car.

Trims are primarily supporting structures of vehicles that are also aesthetically focused and engineered.


 An Overview of Automotive Interior Trims 

Based on the example of a regular passenger car, interior trims include: 

  • Instrument panel
  • Grip handle
  • Switching panel
  • Pillar trim
  • Centre control trims
  • Decoration panel
  • Door module
  • Indicator panel
  • Gear shift knob
  • Trunk board
  • Trunk side trim


Class A Surface 

Class A (also known as Stark) is a term that is extensively used in the automobile industry. This is what describes how the surfaces are going to look aesthetically in the real world after the production. Hence, achieving a high level of detail and precision in this design phase is very crucial.  

The term ‘Class A’ is misunderstood by many. Still, it is typically viewed as the essence of surface modelling since it achieves the highest surface quality levels, and it demands a high level of knowledge about automotive design as well as extreme surface modelling skills. This is understandable since what is seen on the screen is what one would get in the showroom after manufacturing.  

Developing a Class A Surface (CAS) requires a person to be very innovative and creative because it is principally derived from a sketch, which is an artistic approach rather than a technical one.  

What makes the Class A Surface (CAS) creation process so challenging is its demand to combine design, aesthetics, and functionality into one seamless product that also meets the manufacturing constraints and requirements.  

The creation of a Class A Surface is more oriented towards aesthetics and visual appeal. Once a CAS is created, more of the engineering process sets in. The entire product would now have to be optimized for design purposes and the location of components to a much greater extent. 

image source


Software for Class A Surface (CAS) Creation 

Software like Autodesk Alias and CATIA ICEM surf can help convert 2D design sketches into 3D CASs. It should be noted that some CAD software can create CASs but are not dedicated to CAS creation tools.  

The Autodesk product, which is known as ‘Alias,’ is the most widely used CAS creation tool. Autodesk Alias gives the user a high degree of control over the surfaces, along with plenty of commands to further refine their surfaces.  

The next widely used software for CAS creation is the CATIA ICEM Surf by Dassault Systems. This software also has a degree of control and commands that are on par with Autodesk Alias. Hence, the user can be assured that they will get a high degree of tolerance, accuracy levels, surface continuity, and quality.  

Using software that is not dedicated to CAS creation will result in a lot of difficulties while controlling the curves and other control points. 


How it Works 

The dedicated Class A Surface creation software helps turn a sketch into a surface that can be controlled in a three-dimensional virtual space. One would typically require three images, i.e., the front view, side view, and top view. However, the availability of a rear-view sketch or picture will make the entire design process much easier.  

By tweaking these virtual surfaces, one can model any component of the automotive vehicle. Since most vehicles are symmetric about a plane, especially the exterior design, the user will only have to model half of the product and mirror this half about the plane of symmetry to complete the process. 



Plastic design is becoming increasingly popular because of its untapped potential in the automotive sectors, and CATIA has become a gold-standard software in many companies around the world in the automotive industry.

Skill-Lync's Master's certification in Automotive Design using CATIA program has been developed with inputs from industry experts to ensure that students can get employed in a design firm immediately after the completion of the course. Check the course out by clicking here

You can watch part one of this video series here


Get a 1-on-1 demo to understand what is included in the course and how it can benefit you from an experienced career consultant.

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