As an important part of the vehicle's appearance, the car bumper not only plays a role in beautifying the vehicle body, but also plays a key role in vehicle safety. When a vehicle collides, the bumper can effectively buffer external forces and protect the safety of the vehicle body and the people inside the vehicle. However, accident collisions often cause varying degrees of damage to the bumper. At this time, it is particularly important to repair or replace the bumper in a timely manner. This is not only related to the appearance of the vehicle, but also closely related to driving safety. Next, this article will explore in depth the issues related to the repair and replacement of bumpers after accident collisions.
How to judge whether the bumper after an accident collision is suitable for repair or direct replacement?
From the perspective of appearance damage
If the bumper only has some small scratches, it can be understood that this damage is mainly in the surface paint layer and has not damaged the plastic structure inside. In this case, repair can be considered. For example, if there are shallow pits or local depressions, as long as they do not cause overall deformation, there is actually room for repair. For example, those small cracks, as long as they do not completely crack through the entire thickness of the bumper, theoretically, you can try to repair them.
On the other hand, if the bumper is severely deformed, such as the entire shell is twisted or cracked into several pieces, and there are through cracks that can see the internal structure, then the repair is meaningless. Because these damages will directly affect the support capacity of the bumper, in simple terms, it is impossible to effectively protect the body parts.
Analysis from a functional perspective
The bumper mainly plays the role of buffering impact and protecting the body. If the energy-absorbing structure inside has been crushed and deformed after the collision, just like the foam buffer block is completely broken, even if the appearance is repaired, the actual protection effect will be greatly reduced. At this time, it is obviously more reliable to replace new parts.
In addition, many cars now have electronic equipment installed in the bumper, such as radar probes and reversing images. If these precision parts need to be handled at the same time during maintenance, or if it is found that the maintenance cost is higher than replacing new parts, it is better to replace the entire part directly. For example, if the bracket of the reversing radar is broken, the labor cost of replacing the bracket alone may be more troublesome than replacing a new bumper.
Cost considerations
Repairing a bumper mainly involves labor and material costs, such as repainting and shaping. If it is a small area repair, it may take half a day to complete, and the amount of materials used is also limited. But if the entire bumper is replaced, not only do you have to buy a new bumper, but you also have to count the hours of disassembly and commissioning.
Here you also need to consider the condition of the vehicle itself. For example, if you have been driving a ten-year-old car, it may not be necessary to spend a lot of money to repair the original bumper. But if it is a quasi-new car or a luxury car, in order to maintain the original matching degree and the price of a used car, it is worth investing even if the repair cost is higher. For example, some car paints have special colors, and post-painting is prone to color difference. At this time, it is more cost-effective to choose local repairs.
When evaluating the degree of damage to the bumper, which parts and indicators need to be checked?
Appearance inspection
It is necessary to carefully observe the surface condition of the bumper, such as whether there are obvious scratches or dents, as well as some small cracks. It should be noted that scratches may affect the appearance more, while damage such as dents or cracks may mean that there is a problem with the internal structure. In addition, special attention should be paid to whether the edge of the bumper is deformed, such as whether the connection with the body can still maintain a tight fit. If there is a gap or deformation here, it may cause abnormal noise during the vehicle's driving, and may even affect the aerodynamic performance of the entire vehicle.
Internal buffer structure inspection
It is necessary to understand that there are usually buffer devices such as foam materials or honeycomb support structures inside the bumper. Focus on whether these support structures are broken or flattened. For example, if the internal honeycomb panel structure is distorted, it will directly affect the energy absorption effect of the bumper during a collision. In simple terms, it may not be able to effectively protect the body structure when a collision occurs again.
Fixing device inspection
It is necessary to confirm whether the clips and screws used to connect the bumper to the body are intact. For example, check whether the clips have signs of breakage and whether the screws are rusted or loose. The status of these fixings is actually very important. If they are loose, the bumper may fall off when driving at high speed, especially when passing through bumpy roads, which may cause displacement problems, which may bring safety hazards.
What are the common repair processes and procedures for repairable bumpers?
Basic cleaning work
The first step is usually to clean the dirt on the bumper. For example, dust and oil stains must be treated with special cleaning agents. For example, some stubborn stains may need to be scrubbed repeatedly two or three times to be completely removed. Then, the damaged area should be pre-treated by grinding to smooth the rough and uneven areas on the surface. In this step, special attention should be paid to not grinding too hard, otherwise it is easy to grind marks on the surrounding undamaged areas.
Specific repair operations
· Dealing with surface scratches: For example, for relatively shallow scratches, you can slowly apply the corresponding color touch-up pen. It should be noted that when applying, you must wait until the previous coat of paint is completely dry before applying the second coat, so that the color is not easy to fade. If the scratch is deep, you may need to tape the surrounding area with masking tape for partial spray painting, and then use a baking lamp to accelerate drying.
· Dealing with dents and deformations: For coin-sized pits, the mechanic may use a hot melt glue gun to stick a traction pad and slowly pull it out. Sometimes he will use a rubber hammer to gently tap from the inside. If it is a large area of dents, some repair shops now use dent repair devices with LCD screens. This device can display the repair progress in real time.
· Dealing with cracks and damage: When encountering cracks, generally use a plastic welding gun to melt the two sides of the crack, and then fill it with special welding rods. For example, some special locations may require reinforcement on both the inside and outside, and after welding, you have to use a grinder to grind the weld scars flat.
Surface finishing
After all the repair steps are completed, the whole body needs to be polished. At this stage, three different coarse and fine sandpapers are usually changed. For example, first use 600-grit sandpaper for primer, then use 1500-grit for transition, and finally use 3000-grit for fine grinding. After all the processing, you have to use a polishing machine with abrasive paste to create a mirror effect, so that the repaired bumper looks almost the same as the original one. Experienced masters will also use a strong flashlight to check to ensure that no small defects are missed.
When repairing a bumper, how to ensure the strength and appearance quality after the repair?
Cleaning pretreatment stage
The first step is to clean up all kinds of dirt on the bumper, such as dust or oil stains. At this time, you can use a special cleaning agent and tools to do this work. Then perform preliminary grinding on the position that needs to be repaired, mainly to remove the burrs or uneven places that are raised, so that it will be easier to repair later. When grinding, pay special attention to the degree of force and the direction of grinding. For example, if you use too much force, the original damage may become larger, which requires special attention.
Specific repair methods
As for scratch treatment, if it is relatively shallow, you can consider using a touch-up paint pen to handle it. When doing this, you need to find a touch-up paint pen with the same color as the original bumper, apply the paint evenly to the scratch position, and wait for it to dry naturally before grinding and polishing. But if the scratch is very deep, you may have to use a spray gun to do the painting work. Before spraying, you must use masking tape to protect the surrounding area so that the spray range can be accurately controlled, and then spray it according to the effect that is completely consistent with the original color, and finally use baking equipment to accelerate drying.
For the repair of dents, if the area is not large, you can use a suction cup and a crowbar to handle it. The operation steps are to firmly fix the suction cup in the dent position, slowly pull it out, and use a crowbar to gently pry at the edge, so that the dent can slowly return to its original state. But if it is a relatively large dent deformation, at this time you may need to use professional equipment with a hydraulic system to complete the repair.
If there is a crack, you need to use glue or welding rods of specific materials for repair. First, clean the area around the crack very cleanly, then carefully apply glue or fill the gap with welding rods. After the material is completely solidified, repeatedly polish the repaired area, and finally polish it to the extent that it is completely indistinguishable from the surrounding surface.
Finishing stage
After all the repair steps are completed, the treated position needs to be fully polished again. At this time, you can choose sandpaper of different coarseness and fineness according to the actual situation. For example, first use coarse sandpaper to quickly smooth it, and then change to fine sandpaper to slowly trim it. Finally, use a polishing machine with abrasives to do surface treatment, so that the bumper looks as bright as a new one.
If you decide to replace the bumper, what are the specific steps from removing the old bumper to installing the new bumper?
Strength guarantee measures
Choosing the correct repair material and operation method is an important part of ensuring the firmness of the repair area. For example, the material needs to match the material of the original bumper, so that the impact force can be effectively dispersed when it is hit by external force. During the actual operation, special attention should be paid to the construction according to the standard process, that is, each step should be done in place, such as the primer should be fully dried, and the adhesive coating should be even and free of bubbles. After the repair is completed, the pressure bearing capacity must be verified, such as using a press to do a pressure test, or using an impact device to simulate a collision. Only through these tests can it be confirmed whether the repair effect meets the standard.
Appearance quality control
When spraying, the color standards and technical requirements provided by the automobile manufacturer should be fully followed, that is, to ensure accurate color matching and standardized spraying techniques. Before starting to spray paint, sufficient surface preparation work needs to be done, such as using sandpaper to smooth the repaired area and using a detergent to remove oil stains. During the spraying process, special attention should be paid to the uniformity of the paint surface, such as avoiding excessively thick paint layers that cause sagging, or spray guns that are too close to cause orange peel patterns. The final repaired surface should be smooth and burr-free to the touch, and the color should not be significantly different from the original car paint in the sun, and the overall effect should be close to the original factory state.
Quality inspection and acceptance
A complete checklist needs to be established to conduct a comprehensive verification of the repair results, such as checking the firmness of each connection point and checking the consistency of the paint color. Before the final delivery, it is best to let the car owner or a third-party repairman participate in the acceptance, that is, to confirm the quality through multi-angle observation and actual touch. If problems such as weak adhesion or paint particles are found in a certain position, rework should be arranged immediately, such as re-grinding the problem area or re-spraying the topcoat until all indicators meet the quality specifications.
