Pre-impregnated carbon fiber composite material – The future of automotive manufacturing

October 30, 2023March 15, 2024 8 min read

The automotive industry is undergoing a paradigm shift with lighter, faster and fuel-efficient variants on the roads. A major part of this revolution has been marked by the rise of carbon fiber composites wherein its exceptional strength-to-weight ratio and durability have revved up the dynamics of the automotive industry. Taking this impetus to the next level, pre-impregnated carbon fiber composite materials have risen as a viable option in automotive manufacturing. Also referred to as prepreg, pre-impregnated carbon fiber composite materials represent an advanced form of carbon composites. In this article, Nikhil Das, Director at RLZ Motorsports discusses the properties of these materials and their relevance for automotive manufacturing.

Today, pre-impregnated carbon fibre composite materials are increasingly being used in a wide gamut of applications that require materials that display high strength and stiffness while being lightweight. The automotive industry is at the forefront of incorporating these advanced material technologies for its future automobiles.

Revolutionising Automotive Manufacturing

In general, a conventional four-wheeler primarily consists of components made from cast iron and steel, constituting approximately 55% of the overall vehicle weight. Plastic materials make up around 11%, aluminum alloys make up about 9%, and rubber and glass components make up approximately 7% and 3%, respectively. The remaining portion consists of non-ferrous alloys, paints, electric wires and similar elements, contributing to the average weight of a car to approximately 1900kg.¹Today, most manufacturers are desperately trying to bring down the weight of the automobile to make it fuel-efficient and thereby cost-efficient. This can only be possible with the use of lightweight materials without compromising the safety and durability of the vehicle.

Pre-impregnated carbon fiber composite materials come as a viable option to not just reduce weight but also overcome the problem of energy efficiency. Various research states that every 10 kg of weight reduction in a vehicle significantly saves up to 6 to 8% fuel consumption and leads to a drop in carbon emission by 1g/km. Carbon fiber compounds with low weight, high strength, high rigidity, better vibration resistance, fatigue resistance and corrosion resistance, significantly reduce vehicle weight by 60%.

According to a Global Market Insights report, the Carbon Fiber Prepreg market size was valued at around USD 7.3 billion in 2022 and is expected to reach USD 18 billion by 2032, growing at a CAGR of 9.50%. With its exceptional power-to-weight ratio, it is fast becoming a material of choice for various industries seeking lightweight materials that do not compromise structural integrity.²

Dynamics of Carbon Fiber Composites

Pre-impregnated carbon fiber composite material is made by impregnating carbon fiber fabrics with a controlled amount of resin, usually epoxy or phenolic. The resin is typically in a partially cured state, allowing for easy handling and storage during the manufacturing process. The material is then cut into sheets or rolls and stored in a cooled area to prevent complete curing.

Prepreg materials have the ability to provide high strength while maintaining a lightweight structure which is significant for the automotive industry. The controlled resin content and consistent fiber alignment in prepreg lead to superior mechanical properties, making it ideal for automotive applications where weight reduction without compromising performance and safety is crucial. This material is increasingly being used in the manufacturing of almost every part used in an automobile including the entire body panel, chassis, swing arms, wheels and spoilers. Replacing the metal parts and components with carbon fiber brings down the weight by 1/10^th which is a massive reduction to achieve.

Furthermore, the plastic interiors of a car are also being replaced with carbon fiber parts bringing in a 50% reduction in plastic weight. Globally, attempts are being made to make 100 percent carbon fiber cars and bikes. These innovations are specifically occurring in the realm of motorsports, where weight reduction is a key requisite. The use of pre-impregnated carbon fiber brings in a massive weight reduction of the automotive while enhancing the design and aerodynamics of the vehicle.

Metamorphosis to Advanced Material

In the age of technological advancements, Pre-Impregnated Carbon Fiber Composite is increasingly being preferred over traditional materials. This is mainly due to its optimised characteristics. Compared to traditional materials, Pre-Impregnated Carbon Fiber Composite materials offer:

Improved Strength-to-Weight Ratio: The future of automobile manufacturing demands materials that can give increased fuel efficiency. Prepreg carbon fiber composites offer a significantly higher strength-to-weight ratio making them notably lightweight, allowing automotive manufacturers to achieve improved fuel efficiency, reduced emissions and overall improvement in vehicle performance. Statistically, the material has a very high strength-to-weight ratio and density as low as 1.6g/cc making it extremely lightweight. Thus, an average car will give the same amount of power at half the weight, increasing the fuel efficiency by 35%. This is an imperative requirement in the automotive manufacturing industry today.

Designing Flexibility: Prepregs allow for complex and intricate designs that are difficult to achieve with metals with traditional materials. This flexibility in design provides automotive manufacturers with the opportunity to optimise structural integrity and aerodynamics. These composites also offer exceptional mechanical properties, making them suitable for structural components that require high strength and stiffness, and better air resistance resulting in higher speed and lower drag rate.

Higher Corrosion Resistance: Unlike metals, pre-impregnated carbon fiber composites are completely corrosion-free, extending the lifespan of automotive components while significantly reducing maintenance costs.

Lower Thermal Conductivity: Temperature radiates metal and hence increases the thermal conductivity. In conventional vehicles, heat generated by the engine, air conditioner etc leads to increased thermal conductivity in the vehicles. Prepregs have lower thermal conductivity compared to metals, which can be an advantage in applications where thermal insulation is important.

Fatigue Resistance: These materials exhibit excellent fatigue resistance, making them ideal for parts that endure repeated stress cycles, enhancing the overall durability of automotive components. Flexibility impact resistance can be high.

Environmentally Friendly: The removal of excess resin during the impregnation process ensures the reduction of the environmental impact of the material making it more sustainable than other materials.

Overcoming Roadblocks

The Pre-impregnated carbon fiber composite material technology is still in its nascent stage. Thereby the production cost of pre-impregnated carbon fiber composite material is higher compared to traditional materials, primarily due to the specialised manufacturing processes and high-quality raw materials required. This also increases the cost of part manufacturing. For instance, a plastic mudguard of a bike costs around Rs 7,000 while the one made of carbon fiber starts from Rs 12,000. Similarly, the cost of a carbon fiber wheel is higher than a regular alloy wheel. However, despite the price variation, the durability and resilience of the latter are much higher with greater weight reduction and better aerodynamics which transforms the overall quality of the vehicle and decreases the fuel consumption drastically resulting in a significant reduction in the cost of ownership of the vehicle.

Furthermore, prepreg materials have complex processing, as they require specialised equipment and skills to handle and cure. However, with robust advancements in technology and widespread acceptance of the material by automotive manufacturers, the cost of the material is bound to decrease in the years to come.

Overall, although the cost of a carbon fiber vehicle is higher than a conventional counterpart, the higher durability, strength, load-bearing capacity, aerodynamics, lightweight and fuel-saving play a crucial role in making them a cost-saving investment in the long run.

The Way Forward

Pre-impregnated carbon fiber composite materials represent the future of advanced materials for the automotive industry, offering a unique combination of lightweight design, exceptional strength and tailored properties. As ongoing research and technological developments continue to drive the adoption and optimisation, these materials will be an inevitable part of a more sustainable and efficient future of automotive manufacturing.