If the interior of the car is to provide people with a comfortable driving experience, then the exterior of the car is to make the vehicle more beautiful at the same time to protect the safety of the ride. Because of the special function of the car, so the car exterior parts must adhere to the "three" design principles, that is, standardization, serialization, generalization, but also to meet the "six requirements" of rationality, reliability, economy, advanced, easy maintenance, manufacturing process ".

According to the different countries and regions where the models are launched, the design process must fully implement the local regulations and standards. Mainly including the front and rear bumper license plate mounting hole hole spacing size regulations, whether the need to reserve fog lamp mounting holes, lamp installation, external projection requirements and opening size and other related requirements, and about the radiator mask windward area to meet the engine, air conditioning cooling requirements, but also requires the approval of the relevant departments.

In addition, in several parts of the exterior of the car, the requirements of the material also vary. Such as rearview mirror, grille, fog lamp cover and other body parts of the components, need to have better heat resistance, scratch resistance, light resistance, chemical resistance, etc.; luggage rack, car seat to, welding trim and other parts of the direct sunlight all year round need to have better heat resistance, low temperature resistance, light resistance, chemical resistance; wheels, bumpers and other chassis near the parts need to have good rigidity, scratch resistance, low temperature resistance Impact resistance, debris impact resistance, etc.

At present, the plastics used in automobiles are generally PP (polypropylene), PE (polyethylene), ABS (polyurethane), PMMA (polyether ether ketone), PA (nylon), PC (polycarbonate) and so on. And with the strengthening of environmental awareness and researcher's exploration of new materials, the emergence and use of new plastics are gradually expanding to the field of automotive exterior trim. Such as straw, flax, sugar beet, cotton seed hulls and other plants extracted from cellulose, can be made of bio-based plastics used in the automotive field plastic processing performance and use of performance are more ideal, and compared with the traditional automotive manufacturing of metal materials, lower cost, lighter weight also comply with the trend of automotive lightweight, so more and more plastic auto parts to replace the metal. Common automotive exterior parts are front and rear bumpers, mirrors, luggage rack, grille, wheels, lights and their parts, door handle assembly, radiator trim cover, crash beam, wiper, wiper, etc.

1、Bumper: including the front bumper and rear bumper. Bumper can absorb the energy generated in the vehicle collision to reduce the injury to the body parts and occupants. Need to have good impact resistance, weather resistance, paint adhesion and other properties, polyester, polypropylene composite materials and TPO in the plastic bumper is more common.

2, rearview mirror: due to its long-term exposure to sun and rain and other climatic and driving bumps and other factors, rearview mirror materials need to have a certain degree of weather resistance. Taking into account the temperature, humidity, strength, impact and bending performance requirements, but also the material is not easy to age, corrosion resistance, injection molding performance and paint performance and so on. Materials generally can be heat-resistant ABS, PC, ASA, PBT + GF, etc..

In addition, it is also worth noting that, as the advantages of plastics become more and more obvious, in the engine cover, tailgate and fuel tank and other coverings and chassis accessories are showing a trend to expand the use of plastic materials. As the trend toward lighter weight vehicles becomes clearer, the use of plastics in automotive trim is becoming more widespread. Although there is still a long way to go in the application of plastics in automotive exterior trim, but with the support of technology, we have reason to believe that this field will usher in a new climax of development.