Creating a Carbon Fiber Body for a Car: The Balancing Act of Cost and Quality

When it comes to creating a carbon fiber body for a car, the question often arises regarding the best and cheapest way to achieve this goal. This article explores the feasibility and intricacies of both approaches, providing insights into the methods, time commitments, and costs involved.

DIY Carbon Fiber Body Creation: The Recipe for Cost-Efficiency

For those looking to create a carbon fiber body without breaking the bank, a DIY approach is feasible. By utilizing low-stiffness fabrics and affordable materials such as AS4 aluminum honeycomb and plywood or Fiber-Glass Rayboard (garrolite) for hard points, you can get a car body made for around $10-12K. However, this method is highly labor-intensive and demands a significant investment of time.

The process begins with the creation of a male or positive mold that resembles the part you wish to create. From this mold, a female mold is made using chopped fiberglass, polyester resin, and gel coat to ensure the desired smooth surface. This step is both time-consuming and delicate, often taking up to 90% of your time and potentially months to complete. The wet layup method involves mixing resin and impregnating the fabric, then laying it into the mold. A release film and drainage mat are positioned over the fabric, followed by a vacuum bag to compress the part and remove voids.

If you're skilled and have access to a machine shop, large oven, and vacuum pump, this DIY route can be manageable. However, for a large and complex project, such as the 140cm x 50cm carbon fiber chassis that required 2 molds and took 3 months to fabricate, it's clear that this method is not for the faint-hearted.

The Professional Route: Automated Molds and Precision Engineering

For those who prioritize quality and efficiency over cost, the professional route utilizing Numerical Control (NC) machines for creating female molds from CAD files is the best option. This method can significantly reduce time and labor but comes with a substantial cost, typically in the range of tens of thousands of dollars per part. The process involves:

Creating the molds using NC machines, a process that takes only a few minutes per part.

Using unidirectional preimpregnated carbon fiber, which is expensive but provides a lighter and stronger part.

Performing a thorough Finite Element Analysis to determine the optimal layup schedule and determine the direction of the unidirectional ply and the type of fiber used.

Subsequent steps such as mold preparation, layup, and curing are similar to the DIY method but involve more expensive materials and advanced techniques.

Preimpregnated carbon fiber has a longer shelf life and needs to be refrigerated, but despite these considerations, the end result is a superior structure with optimized performance.

Is Mass Production Feasible?

While both methods have their merits, it's important to recognize that creating a high-quality carbon fiber body for a car on a mass production scale is still challenging. The BMW i3 and i8, which have come closest to achieving mass production with carbon fiber bodies, use randomly oriented carbon fiber, which has poorer performance compared to a directional layup.

Mass production requires not only advanced manufacturing techniques but also the ability to scale up the production process while maintaining consistency in quality. Currently, the high cost of materials and the complexity of the process make it difficult to achieve true mass production at a price point that is competitive with traditional materials.

Conclusion

The creation of a carbon fiber body for a car is a complex and labor-intensive process. Whether choosing the cost-effective DIY approach or the professional route, both methods have their pros and cons. The choice ultimately depends on your budget, time constraints, and the desired level of quality and performance. Despite the challenges, carbon fiber remains a compelling material for vehicle manufacturers looking to enhance the performance, aesthetics, and lightweight properties of their vehicles.

Keywords

carbon fiber body, cost-effective car body, car body fabrication