Repairing car sills is one of the most common and critical tasks in body repair that used car owners face. Corrosion of the metal in this area progresses rapidly due to constant exposure to moisture, reagents and mechanical damage, which requires immediate intervention. Restoration of thresholds - the process is time-consuming, requiring not only high-quality consumables, but also the correct choice of welding equipment.
The question of what to cook the thresholds on the car, has no single universal answer, since the choice of technology directly depends on the qualifications of the master and the available budget. You can use classic electric arc welding, a more modern semi-automatic or argon welding, but each method has its own nuances. In this article, we will discuss in detail what tools and materials will ensure the durability of the body and prevent the reappearance of rust.
Before you start cutting metal and applying seams, you need to clearly understand what amount of work you will encounter. Replacement of thresholds It can be partial when only the rotten area is cut, or complete, requiring the dismantling of the entire element. Critically
Selection of welding equipment for bodywork
The basis of quality repair is the right equipment. For working with thin body metal, the thickness of which is often less than 1 millimeter, not all devices are suitable. The most popular solution in garage conditions remains semi-automatic welding (MIG/MAG) which allows you to perform work quickly and with minimal risk of burning through the metal.
Welding inverters for manual arc welding are also used, but they require a high level of skill from the master. At work. electrode It is very easy to overheat the metal, which will lead to warping of the part and violation of the geometry of the body. If you plan to do bodywork regularly, then buying a quality semi-automatic machine will be a better investment than trying to adapt a conventional inverter.
The third option is argon welding (TIG), which gives the cleanest and most aesthetic seam. This method is ideal for visible elements, but it is significantly slower and requires more expensive equipment. For hidden sections of the rapids that will be closed by anticores, the use of argon is often considered redundant, although it guarantees high reliability of the connection.
⚠️ Attention: The use of a welding machine with a current above 100-120 Amperes when working with a body metal up to 1 mm thick is almost guaranteed to lead to burnout and deformation of the part.
Selection of electrodes for manual arc welding
If you have only a conventional welding inverter, you will have to work with piece electrodes. For bodywork, thick electrodes with a diameter of 3-4 mm, which are used for welding pipes and structures, are categorically not suitable. You'll need special ones. small-diameter electrodesIt is usually 2 mm, and ideally 1.6 mm.
Particular attention should be paid to the labeling of consumables. Experienced craftsmen often recommend type electrodes. WONI-13/55 or imported analogues, providing stable burning of the arc at low currents. However, the main problem remains the search for electrodes with a diameter of 2 mm, as they are less common than standard ones.
When working with electrodes, it is important to observe the intermittent welding regime. The arc must be ignited and extinguished with short pulses, allowing the metal to cool. This prevents excess heat from accumulating at one point. Electrode calcination before use is also a mandatory procedure, since the wet coating leads to the porosity of the seam and its rapid destruction.
- 🔥 Use electrodes with a diameter of no more than 2 mm for thin metal.
- 🔥 Choose electrodes with a basic or rutile coating for a stable arc.
- 🔥 Be sure to calcinate the electrodes in the oven or oven before work.
- 🔥 Avoid wide stitches, try to make spot picks.
It is worth noting that the seam made by the electrode will always be thicker and coarser than when welded with wire. After the completion of the work, you will need much more time to clean and level the surface with a Bulgarian file and file.
Semi-automatic welding: wire and gas
Semi-automatic welding is the gold standard for body repairs. As a supplement material here is used a special squirt diameter 0.6, 0.8 or 1.0 mm. For sills, the best choice is a 0.8 mm diameter wire, which provides a good balance between the surfacing speed and the smelting control.
Protection of the welding bath is carried out by gas. The most commonly used is carbon dioxide (CO2) or a mixture of argon and carbon dioxide (80% Ar / 20% CO2). Pure argon for steel welding is not used, as it does not give a stable arc with ferrous metals. The mixture of gases provides a softer arc and fewer sprays, which simplifies subsequent processing.
The technique of semi-automatic welding involves the implementation of short seams or point connections ("hots") with intervals for cooling. Carbon welding It allows you to cook even on rusted or dyed metal (although this is not recommended), providing deep melting. It is important to keep the burner at an angle of 45 degrees and lead it "angularly forward" or "angularly backward" depending on the position of the seam.
Comparison of methods of welding thresholds
To finally define the method, let’s compare the main characteristics of different approaches. Each of them has its advantages and disadvantages that must be considered before starting work.
| Welding method | Difficulty in mastering | The quality of the seam | Risk of burning | Cost of equipment |
|---|---|---|---|---|
| Semi-automatic (MIG) | Low. | High. | Medium. | Medium |
| Electrode (MMA) | Tall. | Average. | High-pitched | Low. |
| Argon (TIG) | Very high. | Excellent. | Low. | Tall. |
| Gas welding | Tall. | Good. | High-pitched | Medium |
As you can see from the table, the semi-automatic wins on a set of factors for the home master. Gas welding, which was once popular, is now rarely used due to the complexity of the setup and high fire risk. Argon welding It gives the best result visually, but requires long training to form a bath.
Technology of replacement and welding thresholds
The process of welding a new threshold begins with careful preparation. Old metal is cut with stock, the edges are cleaned to shine. A new element (insert or single threshold) is adjusted in place. The gap between the parts should be minimal, but sufficient for the boiler.
Welding begins with fixing the part in several points at the corners. This will prevent the element from moving during heating. Then the seam is filled with short sections 2-3 cm long. Chess order. Summoning seams allows you to distribute thermal stress and avoid warping of the body.
After welding work is completed, the seams must be cleaned. First, a petal circle or strip disc is used to remove the main layer of metal, then grinding circles are used to align. It is important not to thin the metal in the seam zone, so as not to create a focus for future corrosion.
⚠️ Warning: Never cook a long seam "silly" without interruption. The metal will heat up, float, and the threshold can lead, making it impossible to install doors.
Anti-corrosion protection after welding
Welding breaks the factory zinc coating and creates thermal influence zones that rust first. Therefore, the question of how to process welded thresholds is no less acute than the choice of welding. The first step is to apply rust-converter all hard-to-reach places and the back of the seam, if available.
After drying the converter and primer (usually used epoxy soil) must provide internal protection. For this purpose, special anti-corrosion compositions are used in aerosol cylinders with a long spray tube. Paraffin or oil-based formulations (type) Movile or Body 950) create an elastic film that does not crack when vibrating.
The outer part of the threshold after leveling with the putty also requires protection. Before painting, be sure to apply acid or epoxy soil on the cleaned metal. Paint and varnish serve as a decorative function, but it is the soil and anticor inside that are a barrier to moisture.
- 🛡️ Use epoxy soil for primary metal protection.
- 🛡️ Treat the internal cavities of the thresholds annually (once a year).
- 🛡️ Do not paint over drainage holes in the sills.
- 🛡️ Use anti-gravel to protect the lower part from stones.
Frequently Asked Questions (FAQ)
Can I cook the threshold without removing the battery?
It's not recommended. A voltage surge when ignitioning the arc can disable the electronic control unit (ECU), the tape recorder and other electronics. Be sure to remove the negative terminal, and ideally, disconnect both contacts.
Do I need to remove the old rapids completely or can I insulate?
If the rust has affected less than 30-40% of the threshold area, partial replacement (insert) is allowed. If the metal has rotted along the entire length or in several places connected by bridges of rust, it is better to replace the threshold entirely to ensure strength.
What current to set on the welding machine?
For metal with a thickness of 0.8-1.0 mm and electrode / wire 2-0.8 mm, the optimal current is 60-80 Amps. The exact value depends on the specific apparatus and is selected experimentally on metal trimmings.
How to fix the holes in the doorstep without welding?
There is no way to replace the welding completely. Copper soldering is possible, but complicated. The use of fiberglass and epoxy is a temporary solution that will not restore the power structure and rot after the season. Just metal to metal.