First of all, from the perspective of safety, the safety mentioned here is not from the safety of cars, but from the safety of pedestrians. If the bumper in front of the car is a steel plate and hits a pedestrian, the pedestrian actually hits the steel plate, while the plastic bumper will rebound slightly due to external impact. After changing the bumper from steel plate to plastic, it is actually taking care of pedestrians, and it can minimize the impact on pedestrians in the event of a traffic accident.
Second, in order to reduce the maintenance difficulty in the subsequent use process, the front and rear bumpers are very easy to be scratched and injured. Steel plates will rust once they are scratched by collision. If it sinks in, it should be made into metal sheets and plastic parts. Don't worry about rust when painting. Like Brother Miao, I don't care if the bumper paint is scraped off. Because there is no need to worry about rust, even if it is sunken, it can be restored to its original state with boiling water. Even if it is completely rotten, the cost of changing plastic will be much lower than that of changing steel plate.
Thirdly, replacing bumper with plastic is beneficial to energy saving and emission reduction of automobiles. With the increasingly stringent emission requirements of automobiles, every kilogram of weight loss in automobiles can achieve unexpected results. Therefore, when designing a car, these accessories that do not affect the safety and structure of the car will gradually be replaced by lightweight accessories.
Fourth, automobile factories can indeed save production costs. If the body panels are all steel plates or iron plates, then casting will be much more difficult. Because plastic parts can be formed more abundantly and are easier to form than steel plates, the car factory will reduce the cost in manufacturing and production.
Having said so many benefits, there are still many friends who are worried about safety. In fact, the front and rear bumpers and body parts of the car will not have an essential impact on the safety of the car. Because when a car collides, it is not the cover outside the car body that protects the occupants' own safety, but the skeleton of the car. Body panels play a decorative and aesthetic role and will not have a fundamental impact on the safety of automobiles.
With the further improvement of automobile emission requirements and lightweight requirements, the proportion of metal parts may be further reduced in the future, and more composite materials and lightweight materials will be used in the car body.