How to securely solder a damaged bumper: DIY repair
Most often, minor accidents occur, as a result of which bumpers are most often damaged. In doing so, they may suffer damage such as scratches or cracks. Repair of damage of the latter type is carried out using soldering technology. In this article, do-it-yourself soldering of car bumpers is considered.
Sequence of work
Bumper repair includes several stages. The following is the sequence of their execution:
- First of all, you need to dismantle the damaged bumper from the car.
- Then proceed to the preparatory work. They consist in cleaning the part by washing, degreasing, removing paint and varnish material from the damaged area with a grinder with a P240 wheel.
- If the bumper is split into several fragments, they are combined into the original integral form, joining the edges.
- After that I start soldering. The seams are tightened with staples, placing them at intervals of 1-2 cm at a depth of no more than half the thickness of the bumper.
- Then the plastic layer is deposited with a soldering iron tip to prevent corrosion.
- After cooling, the seams are cleaned with a grinder with a P240 wheel, blown with compressed air. To remove lint and hairs, use a tool such as a hair dryer.
- Then putty is applied to the surface of the bumper with a rubber spatula. In hard-to-reach places, application is carried out with a finger or any suitable object. After the material has hardened, the surface is ground with a machine with a P120 wheel.
- Next, the entire part is covered with primer in two layers with an interval between them of 15 minutes.
- A light-colored developing layer is applied on top, using a dark base underneath. After drying, the surface is ground with a P800 wheel. The remaining stains are removed with nitro putty. Then wet grout the surface of the bumper with a P1000 circle using grinding equipment.
- After drying, the surface is wiped with napkins and degreased. Paint is applied over the primer in 2-3 layers.
- Finally, the surface of the bumper is also varnished in 2-3 layers.
To solder the bumper with your own hands, you will need equipment and supplies. The main ones are epoxy glue and fiberglass, instead of which a metal mesh with 1 mm cells can be used. In this case, the strength of the seam will be significantly higher than when using fiberglass.
Plastic electrodes are also required for soldering. They can be purchased as a set, which includes several options that differ in thickness and material composition.
It should be borne in mind that the required thickness of the electrode is determined by the location of the seam. Thus, the thicker elements of the "B" and "C" series are suitable for filling deep cavities, and for fixing the reinforced mesh and for welding the stitch on the outer part of the bumper, flat gaskets of the "A" series are used.
The heating equipment for soldering the bumper can be represented by a soldering iron. Instead, you can use a tool such as a technical hair dryer. It should be noted that for professional repairs in service centers and workshops, other equipment is used, namely a thermal gun.
Do-it-yourself bumper repair also requires abrasive materials. For rough grinding, sandpaper with a grit of 80 is used, and finishing is carried out with a material with a grit of 180-200. Staples to strengthen the seams are used from a construction stapler. However, you must first shorten the "legs".
First, repairs, including preparation and soldering, are carried out from the inside of the bumper, and then from the outside. Pulling is the first stage of work. It is especially relevant in the case of a serious violation of the structure, since it is very difficult to solder such damage on your own.
First of all, you need to cut the metal fasteners with construction scissors or a metal sheet, depending on the characteristics of the damage. Then you need to make holes for the bolts with a drill. Screws are inserted into them and fastened with nuts on the back of the bumper. If the repair is done by hand for the first time, fasteners should be installed from the inside. It is desirable to do the tightening from the back side in order to preserve the aesthetic properties and shape of the part. The plate is installed and fixed outside the gap. The screws should be as far away from it as possible along the course of the bolt in the fastener. The drill is installed in the far part of the plate. If you install the bolts correctly, the unevenness will be restored without violating the geometry of the bumper.
Next, you need to drown the top of the bolt into the bumper. To do this, around its head, it is necessary to make a hole with a drill of a smaller diameter, observing the angle of the cap. In this case, it is required to create a rim of not too small depth, but also not to drill through the bumper, as this will cause the bolt to fly out. It must enter the recess with some effort, otherwise the crack will open again.
The bolts are installed from the outside, and from the inside - the fastening web, and the nuts are tightened. Remember that if you tighten them too much, the bumper may crack, and if it is loose, the connection will disengage over time.
If the crack is located in the curved part of the bumper, the plate must be shaped accordingly. There are various ways, but in any case, the plate should be kept at the same time from the back of the bumper under the defect. In this case, when tightening the bolts, the crack will converge.
The first stage of soldering begins with the fact that the electrodes are laid along the seam on the inside of the bumper. After that, one of its ends is fixed and soldering starts from it. The principle of operation is that the thermal energy of the heating device is directed to the electrode.
If the equipment used is a soldering iron, it is simply pressed against the electrode, and the hair dryer is directed at it. Under the influence of high temperature, the electrode melts and fills the recess of the scar. The heat source, that is, the heat flow that creates a hair dryer, or a soldering iron tip is moved from the periphery to the middle line of the stitches perpendicular to the seam. As the work progresses, the free end of the electrode decreases, melting. During the second pass, the side zones are captured.
Along the passage of the entire area, the bubbling cooling material is smoothed with a blunt object. For this, a wooden handle of any tool is quite suitable. Smoothing the material in hard-to-reach places of the bumper is carried out with fingers.
It should be taken into account that the cooling time of the soldering area is about 3-5 minutes, and the seam hardens after a few hours.
The seams are reinforced with a metal gasket for reinforcement. The mesh is well suited for a plastic bumper. In order for the mesh to be well fixed to the part, you need to pass the bumper plastic through its cells. That is, the device must be pressed into it to a depth of at least 1 mm. For heating, use a hair dryer or a soldering iron. After the material has cooled, its excess is removed by grinding.
In the case of do-it-yourself soldering of the bumper for the first time, it is recommended to do it from the outside, since soldering from the inside requires great skills. In case of illiterate work from the inside, cracking of the primer and violation of the structure of the part is possible. In this case, the repair is carried out without electrodes. Using a hair dryer or soldering iron, heat the edges of the crack. Then the defect is soldered.
If the bumper has changed shape as a result of an accident, its repair is also possible. To do this, it is heated using a hair dryer, and the geometry is aligned with heat-resistant gloves. It should be noted that the equipment in question, such as a hairdryer or a soldering iron, when used according to the described technology, is suitable for restoring only plastic bumpers. And for plastic bumpers, this repair method is optimal. This is because repair by gluing is ineffective in this situation.
Adhesives, like most resins, including epoxy, are not suitable for bonding thick plastic. Using a plastic mesh will also not help create a reliable connection.