Carbon fiber hubs can reduce the wheel's moment of inertia and the combined mass of the wheels, suspension, and other directly connected components that are not supported by the suspension (called non-spring mass), resulting in a series of benefits. The reduction in rotational inertia and unsuspended mass (possibly up to 50%) allows us to achieve faster acceleration at a lower cost; reduced braking distance allows better contact with the road (mechanical grip) to improve handling And reduce road noise.
But the price tags of carbon fiber wheels (hybrid and all-composite materials) make it impossible to meet the needs of many consumers. Wheels are likely to be found only in ultra-high-end sports cars and luxury cars. However, some wheel companies recognize the market potential of low-cost carbon fiber wheels and are working hard to find solutions. The method varies from the materials used to the manufacturing and assembly of the wheel components. Some combine carbon fiber components with aluminum for hybrid wheels. Some people use prepreg to make wheels.
The goal of American ESE Carbon is to make carbon fiber wheels available to more driving crowds. The company added a five-axis CNC precision machining team, advanced structural composite parts functions, tailored fiber optic placement machines and robots to achieve automated production. The company plans to release its E2 series of one-piece, single-cured all-carbon fiber composite car wheels next year. The wheels of ESE weigh only 17 pounds and the axle weight is 3,850 pounds, so that the total weight of the vehicle that it can support does not exceed 6,800 pounds. Relevant personnel said that traditional aluminum wheels that can withstand the same weight will weigh more than 30 pounds.
E2 is a five-spoke design based on general sports aesthetics, with a concave deep bowl appearance. Hermida said the company's inspiration came from the design of Porsche aluminum wheels, which were then optimized for carbon fiber. The grinding wheel uses a high-temperature epoxy resin system with high transparency and provides customized surface treatment solutions, including transparent gloss, clear matte and customized colors.
According to the recommendations of the American Society of Automotive Engineers (SAE), ESE's carbon fiber wheels are 80% certified. This regulation applies to all currently manufactured wheels, including metal wheels. In addition, the company is likely to have the first integrated wheel on the market certified under the new composite wheel recommended practice SAEJ3204, which has just been published by SAE. Like the SAE recommendation for metal wheels, this new composite wheel recommendation resolves durability issues through various fatigue and impact tests. It also adds new requirements to consider the unique environmental impact of composite materials. Staff have been actively participating in this new recommended practice working group, sharing data and providing prototypes for SAE committee development and testing.
Internally, ESE's engineering team is working to ensure that E2's performance exceeds the minimum SAE recommendations. Years of prototype testing and physics-based simulations have led to the current E2 design.
Shift to custom fiber implants
ESE's wheels are manufactured using custom fiber placement technology (TFP), which the company says allows TFP to produce carbon fiber components with good mechanical properties quickly and in large quantities. The working principle of TFP is to arrange fiber bundles, place them where needed for structural performance, and then stitch them to a compatible base layer. This process replaces the traditional method of cutting woven fabric into the desired shape. ESE uses industrial-grade carbon fiber tow and TFP technology from Germany to sew the plies, creating a near-net shape preform.
By controlling the path of the tow material when sewing the tow material into the desired geometry, the material can be placed only where it is needed in the final preform. The fabric area that must be cut off in the traditional laminate design does not need to be stitched at all. This process not only reduces the initial waste generated when cutting a woven fabric into a certain shape, but also reduces the waste caused by post-processing due to its ability to adapt to complex geometric shapes.
Before transitioning to TFP, ESE initially used traditional carbon fiber fabrics, a technology that allowed the company to reduce the number of layers by 50%, thereby creating a simplified layering process and minimizing waste. Relevant personnel said that after using TFP, carbon fiber waste has been reduced from about 40% of traditional carbon fiber fabrics to less than 10%. In addition, the technology also improves the quality of the layup, optimizes fiber orientation, and increases design flexibility.
There are many bends on the spokes, which increases the number of layers. The direction of the carbon fiber layer of the traditional fabric is limited. With TFP, it is possible to create straight or curved patterns in almost any direction, allowing the design of optimal laminates and managing loads and pressures more efficiently than traditional fabrics.
These improvements have resulted in significant cost savings for ESE wheels. Before switching to TFP, layup was the company's production bottleneck. Each mold can produce more parts per day, which has a positive impact on the time, labor and total investment of each wheel.