With the advancement of automobile technology, the lightweight of automobiles has gradually become the primary goal of its development. The energy-saving and environmentally friendly materials that China vigorously promotes development and research are slowly replacing traditional industrial materials.
 
1. Significance of automobiles with light weights
The significance of automobiles with light weights cannot be overstated. In today's world, where environmental concerns are at the forefront of our minds, reducing the weight of automobiles is crucial for several reasons. Firstly, lighter cars consume less fuel. With rising fuel prices and depleting natural resources, it is imperative to find ways to reduce our dependency on fossil fuels. Lighter vehicles require less energy to move, resulting in improved fuel efficiency and reduced emissions. This not only helps combat climate change but also saves consumers money at the pump. Secondly, lightweight cars offer better performance and handling. The reduced weight allows for quicker acceleration and improved maneuverability on the road. This enhances both the driving experience and safety for passengers. Furthermore, lighter vehicles have a positive impact on road infrastructure. Heavy cars exert more pressure on roads, leading to increased wear and tear over time. By reducing vehicle weight, we can alleviate this strain on our roadways and extend their lifespan. Lastly, lightweight automobiles promote innovation in design and materials. Manufacturers are constantly seeking ways to develop stronger yet lighter materials that enhance safety without compromising performance or comfort.
 
In conclusion, the significance of automobiles with light weights extends beyond mere convenience or aesthetics. It has far-reaching implications for fuel efficiency, performance, safety, environmental sustainability, and infrastructure maintenance. As we strive towards a greener future with sustainable transportation options, prioritizing lightweight vehicles becomes increasingly important for society as a whole.
 
Thin-walled materials for bumpers
Thin-walled materials have become increasingly popular in the automotive industry, particularly for the production of bumpers. These materials offer numerous advantages over traditional thick-walled materials, including weight reduction, cost-effectiveness, and improved fuel efficiency. At present, plastic bumpers are mainly produced through injection molding, and the mainstream material used is modified polypropylene (PP). European and American OEMs focus on safety factors. The bumper’s wall thickness of mass-produced models is generally 2.7 to 3mm, and is developing towards 2.5mm. The plastic parts of Japanese cars focus on reducing fuel consumption and thus saving energy. OEMs have been developing towards thinner bumpers from the beginning. Now most bumpers’ wall thicknesses are 2.2 to 2.5mm; a small number of parts have multiple improved designs, and the wall thickness has reached 2mm; is still on a downward trend. Most of them are developed simultaneously with material suppliers. The wall thickness of the bumper of models in the research and development stage even reaches 1.8 to 2mm. The wall thickness of mass-produced bumpers of domestic OEMs is mostly about 3mm, while the thinnest wall thickness of Chinese plastic parts of cars is 2.6mm. In fact, OEMs’ requirements for bumpers are constantly changing. From 2003 to the present, the requirements for bumpers have mainly focused on low cost, wall thickness reduction to 2 to 3 mm, rapid prototyping, and lightweight while meeting high requirements for strength and other key aspects.
 
Using plastic instead of steel for automobiles
The automotive industry has long relied on steel as the primary material for manufacturing automobiles. However, in recent years, there has been a growing interest in using plastic as an alternative to steel. Plastic offers several advantages over steel, including its lightweight nature, cost-effectiveness, and improved fuel efficiency.  Composite materials, especially carbon fiber composite materials, are widely used in the development of automobile technology to achieve lightweight automobiles. They provide a new idea for traditional automobile design concepts and also have a certain impact on manufacturing automobile bodies, traditional manufacturing processes such as stamping, welding, painting and final assembly as well as management models. The density of composite materials is relatively small, with high strength, good thermal stability, good corrosion resistance, obvious anti-vibration effect, and impact resistance. At the same time, the processing technology is mature and easy, and the parts are safe, comfortable, and beautiful, which meets the requirements of low cost, vehicle weight reduction, and high strength, and its comprehensive performance can almost surpass that of aluminum.
 
Environmentally friendly materials
In recent years, there has been a growing concern about the impact of automobiles on the environment. As a result, there has been a shift towards using environmentally friendly materials in car manufacturing. One such material is polypropylene (PP), which offers several advantages in terms of sustainability and reduced environmental impact.
 
With the development of the automobile industry, environmental protection and the potential harm of air pollution in cars have attracted more and more attention from consumers. This is also an industry problem that major automobile OEMs need to solve urgently. Volatile organic compounds from interior components are one of the main causes of air pollution inside the car. Most interior parts contain a certain amount of volatile organic compounds, mainly including formaldehyde, acetaldehyde, acrolein, benzene, toluene, ethylbenzene, xylene, styrene and other substances. When the temperature reaches a certain value, these volatile substances will be released, producing unpleasant odors, and even causing headaches and harm to the body. Therefore, a large amount of research is devoted to improving the impact resistance and low emission properties of PP composite materials to prepare high-strength, low-emission environmentally friendly automotive interior composite materials, such as selecting appropriate tougheners, filling materials, and coupling agents and other processing aids can be used to fill, toughen and blend modifications of PP, or the VOC and odor of PP products can be controlled by changing extrusion process conditions, adding adsorbents and other methods. The method of preparing polypropylene automotive interior composite materials has been reported at home and abroad. Trassl and others proposed a concept of ultra-light automotive interior parts based on foam particles. This kind of automotive interior parts with a multi-material system will be lighter. However, the emission performance of automobile interiors has not been studied. Chu and others developed a low VOC content PP and conducted a series of research and development on its processing technology and application in automotive interiors. They pointed out that when preparing production materials, high-quality, high-purity masterbatch and additives, using new polymerization technology can fundamentally control the content of volatile organic compounds in the produced polymers. For production and processing, adding efficient odor adsorbents and extraction agents to the matrix material, odor organic compounds are adsorbed in the polymer matrix.
 
5. Summary
The current main ways to achieve lightweight automobiles include structural optimization design, optimizing the product design structure through advanced CAE analysis technology, the selection of new materials like the application of high-impact steel, and the replacement of steel with new materials like carbon fiber reinforced composite materials and advanced molding technology, such as micro-foam injection molding process. Integrate material design, structural design, and process design to reduce the weight of vehicle parts while maintaining their strength and reliability. The comprehensive indicators for achieving lightweight automobiles are weight reduction, environmental protection, consumption reduction, safety, and comfort. However, it must be ensured that as the weight of the automobile product itself is reduced, the overall performance of the automobile is enhanced. Lightweight and environmental protection is a rich and wide-ranging topic involving basic theory, engineering design, factory manufacturing, and practical verification. It will go through a hard-working exploration process. In the near future, cars will lead the trend of a new generation with a new image of cleanness, power and lightweight.