Why Big Car companies design their models with clay?

The use of clay models in car manufacturing dates back to the 1930s, and it remains a critical component of the design process for many automakers today. Despite the availability of high-tech virtual reality software, some companies continue to use clay models in the design process. So why are these models still so valuable, and how are they created?

The clay used in these models is a specialty product that is different from traditional water-based ceramic clay. The clay comes in bars or cylinders roughly the size of tennis ball cans and is more malleable and sticky than other types of clay. The modeling team turns design sketches into scaled-down clay models that are typically just over a meter long. The modelers then use 3D scanners to convert the physical clay model into digital graphics that can be edited and refined using software, including virtual reality aspects.

To create a full-size model, the modeling team first builds a frame out of steel and wood to support foam blocks. Making a model entirely out of solid clay would be too expensive and weigh several tons. The clay is heated for 24 hours in a special oven set to around 140 degrees Fahrenheit to make it more workable. The modelers then spend a few days slathering one to four inches of warm, soft clay on different parts of the model. Once the clay cools and stiffens, it is ready for shaping.

The milling machine then carves out a full-size model over the course of one to two days. However, the model is far from finished at this point. Modelers must spend time smoothing out surfaces, corners, and edges by hand, carving out important details like hoods, roof lines, and fenders. They use a collection of razor blades and wires that look like medieval surgical instruments to create the desired shapes and contours.

Despite the advances in technology that have made the design process faster and more efficient, clay modeling remains a valuable tool for automakers. The versatility of clay allows designers to experiment and make changes that may or may not work but can be easily fixed if necessary. If modelers make a mistake, they can use a hot air gun to soften the clay and either add more material or remove it.

Another advantage of clay models is that they allow automakers to test a car's aerodynamics in a real-life setting. While computer programs can help, they need a physical model to thoroughly test how easily air flows over, under, and around the car on the road. To do this, automakers use a giant wind tunnel with a massive fan that spins. Engineers use a smoke wand to see how easily air flows over, under, and around the car on the road, a process called drag. This helps measure how much energy the vehicle needs to move and informs how much fuel the car will consume eventually.

In some extreme cases, companies can spend over 1,000 hours in the wind tunnel testing a model's design before committing to full-scale production. During this process, modelers are standing by, ready to make adjustments on the spot.

So why do some companies still use up to a hundred tons of clay each year, and why do some models take years to build? Clay models are built in top-secret studios that are even more restricted than manufacturing plants. Inside these studios, designers develop vehicles that haven't even been announced yet, so the secrecy and confidentiality of the design process are crucial.

Car companies also continue to use clay models because they offer a level of craftsmanship that cannot be replicated by computer programs alone. While computer-driven machines can do in hours what used to take days or even weeks of manual labor, the tools used for actual sculpting are mostly the same as they were in the 1930s. The combination of materials and the amount of labor required is what leads to the high price tags for automakers.