Are both the front and rear bumpers made of plastic
The car bumper is a safety device that absorbs and reduces external impact forces and protects the front and rear of the vehicle body. Many years ago, the front and rear bumpers of cars were made by stamping steel plates into channel steel, which was riveted or welded to the longitudinal beams of the frame. There was a relatively large gap between them and the car body, which looked very unattractive. With the development of the automotive industry and the extensive application of engineering plastics in it, automotive bumpers, as an important safety device, have also embarked on a path of innovation. Today's front and rear bumpers of cars, in addition to maintaining their original protective functions, also strive for harmony and unity with the vehicle body shape and pursue their own lightweight. The front and rear bumpers of a car are both made of plastic, which people call plastic bumpers. The plastic bumper of a general car is composed of three parts: the outer plate, the cushioning material and the crossbeam. Among them, the outer plate and buffer material are made of plastic, and the crossbeam is formed into a U-shaped groove by cold-rolled thin plate stamping. The outer plate and cushioning material are attached to the crossbeam.
The main reasons why it is not recommended to repaint the front bumper include that the original factory paint cannot be replicated, the plastic material makes the repaint prone to peeling off, the obvious color difference affects the appearance, the cost-effectiveness is low, and it may reduce the vehicle's residual value. Youdaoplaceholder0 These factors make it usually not necessary to repaint minor scratches.
Youdaoplaceholder0 the irreplaceability of original factory paint
The original factory paint is produced through a high-temperature baking process, forming a four-layer structure (electrophoretic layer, intermediate coating, color paint layer and clear coat layer), which features excellent scratch resistance and adhesion. However, for touch-up painting, only low-temperature repair paint can be used, which cannot meet the same process standards, resulting in a significant decrease in durability. For instance, experiments show that the adhesion of plastic parts after repainting is only one third of that of the original factory, and they are prone to peeling or a grainy feel.
The characteristics of plastic materials limit
More than 90% of the front bumper is made of polypropylene (PP) plastic, which has a tight molecular structure and low surface energy, making it difficult for paint to adhere firmly. Residual mold release agents or oil stains from production further reduce adhesion, and the paint is prone to peeling off or becoming uneven after touch-up. In addition, plastic does not rust. When there are minor scratches that do not damage the primer, it can be repaired simply by sanding or waxing, without the need for repainting.
The actual defect of touch-up paint is
Youdaoplaceholder0 Color difference issue : Touch-up painting requires on-site color mixing, but the original paint fades after the vehicle is used, making it difficult to match exactly. The absorption rate of paint by plastic and metal differs by nearly 40%, resulting in significant color differences (for example, the color difference ΔE value of Tesla Model 3 reaches 3.8), and it is more exposed to sunlight.
The impact of retention rate on : extensive touch-up painting may be misjudged as the vehicle having experienced a major accident, which affects the transaction price of used cars; If only the bumper is replaced, it will not be regarded as an accident vehicle.
Whether the front bumper needs to be repainted if it is scratched depends on a comprehensive assessment of the degree of damage, aesthetic requirements and repair costs . Minor scratches that do not damage the primer can be polished. For extensive damage or exposed primer, it is recommended to spray paint for repair.
Youdaoplaceholder0 Handling suggestions and necessity analysis
Youdaoplaceholder0 Minor scratches treatment plan .
Foreign object contamination: It can be restored by wiping with a dedicated cleaner.
Youdaoplaceholder0 situations requiring painting for repair .
Deep scratches reaching the primer and covering a large area: Partial or full bumper painting is required. Professional color matching can reduce color differences (recommended at 4S stores or large repair shops).
Obvious damage to white/light-colored car paint: As the color difference is more noticeable, it is recommended to repair it first to maintain its appearance.
Post-spray painting quality differences: The adhesion and weather resistance of new paint are weaker than those of the original factory paint, and color differences may occur after 1-2 years of use.
The impact of on vehicle value
Frequent repainting records may be identified as accident vehicles, resulting in a depreciation of the used car by 3% to 5%.
The bumper is a plastic part. When the vehicle body structure is not damaged, the impact of a single repair on the retention rate is limited.
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