Soldering copper, aluminum, steel

1st rule: It is necessary to correctly insert the tubes into one another freely, but without excess gap, to a depth of at least 5 mm. Apply solder only after the soldering area has completely warmed up and in no more quantity.

2nd rule: Do not apply too much solder, this will lead to excess material consumption. But saving is also not recommended, since there will be a high probability of freon leakage in this place. Do not overheat the solder so that it does not start to bubble and do not try to cool it as quickly as possible. This can also lead to microcracks and leaks.

3rd rule: The depth of the tube entry is a very important parameter, since many novice craftsmen insert the tubes 1-2 mm, starting to solder immediately, which leads to internal blockage of the tube and an interesting case for the next master.

Always choose high-quality solder, since high-quality solder is one of the keys to good soldering.

One of the difficulties for any novice craftsman is soldering aluminum and steel with copper. And due to the heterogeneity of these materials, it is very difficult to solder them together, and when the temperature of one has already reached the desired value, then the other is either already overheated and melts, as happens with aluminum, and heats up so that the solder simply bounces off it.

As you can see from the picture, the main “trick” is heat distribution. As we know, all substances are different and distribute heat differently across their plane. Therefore, when heating the junction of copper and aluminum, it is necessary to first heat the copper, which will not melt, as aluminum can do. Copper, in turn, gradually begins to heat the aluminum and transfer some of the heat to it, which leads to the desired temperature distribution.

When working with steel, you need to understand that the steel will heat up much earlier and from the beginning you need to find the optimal temperature to “tin” it, apply a thin layer of solder, and only then heat the copper and add solder. As the metal warms up and reaches the desired color.

For high-quality soldering you need three main points. The first is a well-prepared knock or soldering point, i.e. it must be cleaned of rust and paint. The second very important point is the selection of solder and flux, which we will discuss below. And of course the third is the burner itself.

Three types of burners are used in the repair of household refrigerators:

The first option is the cheapest and incorrect, soldering with a probane-butane mixture. The disadvantage of this method is that the soldering area is heated too slowly, and in some cases it is impossible to warm up the knock at all, for example, if it is located close to the compressor.

The second option is a burner with MAPP gas, the most common burner option, since the price of a refilled cylinder is not high, and the cost of the burner itself is not prohibitive. Plus, it is possible to buy burners with hoses and piezo ignition.

The third option is a MAPP burner, but the disadvantage of these burners is that the flame is too large and the temperature rises sharply. To eliminate this, professional craftsmen buy burners with two hoses to mix oxygen with the gas. In this case, you can make a minimum feed, and the temperature will remain high.

For soldering aluminum to aluminum, it is better to use Gastolin 192 or 195 solder, which has a different melting point. For 195 solder it is slightly higher than for 192. Therefore, 192 is better suited for tubes, and 195 for thick-walled metals with vibration loads.

It’s worth noting right away that not a torch, not the best solder, will not replace your experience. Therefore, in order to learn how to solder copper, steel and aluminum, you need to take a pipe cutter and cut yourself pieces of pipes and then solder, solder and solder.

To solder thin return pipes, in modern MAPP refrigerators it is better to replace the burner with a gastolin burner, which has a flame temperature lower than that of the MAPP burner.