On the technology of tinning during soldering of body parts
In body repair, one of the ways to connect parts (metal, metallized) is soldering. This technological process is carried out thanks to the molten solder. When it hardens, due to diffusion into the base metal, a reliable connection of the fastened parts of the car occurs. During such work, the melting temperature of the solder is much lower than that of the base metal, which does not melt. The process of work and tinning of the car body during its implementation is described below.
General information about technology
The sequence of the process is as follows:
- preparation of parts;
- coating surfaces intended for soldering with flux;
- body tinning;
- soldering .
The connection of metal and metallized elements when soldering with tin is carried out due to the deposition of a fusible alloy. With this method, you need to use only solder that contains lead in addition to the base metal. The use of pure tin is impossible, since it is not sufficiently fluid, which means that it does not penetrate well between the supporting surfaces of the body parts to be soldered. In addition, when cooled, the metal without impurities becomes brittle, therefore, depending on the type of work performed, a certain percentage of lead must be added to it. Most often, in percentage terms, it looks like this: tin 33% and lead 67%.
It should be noted that aluminum and its alloys are not soldered with tin solder; there are special compositions for them.
For other metals, lead-tin rods are used (their thickness may vary), tin powder, wire wound on a coil, up to 3 mm in diameter. The degree of solder melting is usually 230-250.
The soldering iron should not be red-hot, as this will lead to the evaporation of part of the tin solder and the copper will oxidize, and the soldering conditions will worsen. Use the flame of an air-gas or oxy-acetylene welding torch to heat the tool. The tip of the soldering iron must be tinned in solder before starting work.
Before soldering, do-it-yourself, be sure to do a tinning, regardless of what kind of work is ahead: applying solder to sheet parts or connecting two elements.
Always have everything you need close at hand, especially solder, especially when it comes to tinning with a soldering iron.
Preparation of metal parts
The first stage of work in soldering parts is their preparation. The metal surface must be thoroughly cleaned of residues of compounds and, in general, of everything foreign. To remove paint or its residues from the body, you need to process the surface of the car parts with a mop, having previously cleaned the metal with a file with your own hands. Such work is often carried out with a glass skin and therefore care should be taken, and if it is new, take into account that the powder may not completely settle due to this. To remove the remnants of greasy compounds, the parts must be washed with trichlorethylene or gasoline.
Flux coating of surfaces to be soldered
Flux coating of body parts is necessary in order to prevent oxidation before heating and during soldering with tin solder. To properly perform the work at this stage, you should first watch the video recommendations on the Internet. The flux can be zinc chloride, substances based on it, rosin, stearin.
Zinc chloride is obtained by dissolving zinc in hydrochloric acid. For this procedure, a suitable container is lead. As a result of the reaction occurring in it, hydrogen is released, zinc chloride remains at the end of it. After using the latter as a flux, body parts should be washed immediately to prevent acid exposure. Neutral substances based on zinc chloride are also used in the work. Most often, they process places that are subject to soldering.
For work with copper electrical wires, rosin is used as a flux. To perform other types of work, in particular plumbing, use a thick flux or stearin.
The body is tinned immediately before soldering. This stage is easy to do with your own hands, even by an amateur master. In these works, a soldering tool, open fire, and solder are used.
When tinning is performed with a soldering iron, solder is brought to its tip and waited for it to begin to drain onto the part. This is the so-called wetting, after which the soldering iron is gradually moved and a thin layer of lead-tin composition is applied to the surface of the car part. The end of the solder in this version of the work needs to be covered with flux from time to time.
With an open fire, bars or tin powder are used. When the latter is used, the part is heated, wiped with a rag with a powdered composition applied to it. In contact with the surface, solder in the form of tin powder melts, reliably adhering to the metal. When tinning oblique or vertical parts, they are wiped with a rag from the bottom up.
Carrying out soldering
After tinning, the car parts are soldered (it is advisable to preview the video with recommendations on how to do it correctly). Before starting this stage of work, body elements are covered with flux, they are finally placed as necessary, but always with overlap. It is undesirable to install end-to-end, since such soldering is unreliable due to the low mechanical strength of the solder.
The parts are connected with clamps or other devices that do not interfere with their heating. The soldering iron raises the temperature on the surface, as a result, the solder is melted (if there is a need, you can add the required volume from the common plate).
Solder is applied to sheet parts in two ways: using an open flame or a soldering iron.
An open flame heats the sheet and when wiping the working plane of the body, a layer of paste-like consistency remains after the solder bar. Then wipe the surface with a rag with flux, smoothing the heated composition.
With a soldering iron, a piece of wire or a bar of solder is melted, then pressed against the part. It is necessary to ensure that the composition does not overheat and does not drip along the inclined parts.