1. Precautions for changing copper to aluminum
) Wire diameter change (because of the difference in conductor resistivity) Aluminum wire diameter = Copper wire diameter × K
K is the value of the empirical coefficient according to the actual application.
B) Design modification of wire duct (different wire diameter)
To ensure the resistance of the original conductor, which leads to an increase in the conductor wire diameter, and at the same time also increases the slot full rate to a certain extent.
C) Changes in winding (difference in tensile strength)
Aluminum has worse toughness than copper, so it is necessary to reduce the winding tension and appropriately reduce the winding speed
D) Change in connection method (difference in welding performance between copper and aluminum)
Compared with copper, aluminum is very easy to oxidize and welding is very difficult. Therefore, the original copper wire welding process and materials are used, and tinning is impossible, so the connection must use aluminum enameled wire special soldering materials and processes.
2. The key to changing copper to aluminum technology
As far as the aluminum enameled wire itself is concerned, compared with copper, the resistivity is different. Therefore, if copper is changed into the aluminum enameled wire, as long as the diameter of the aluminum wire is increased according to the resistivity ratio, the aluminum wire will be better in terms of temperature rise, current, and energy efficiency. No worse than copper wire, so in terms of design, there is no problem in changing copper to aluminum, but because metal aluminum is active, it is easy to oxidize and it is difficult to the tin. Therefore, the key to the application of aluminum enameled wire lies in how to solve the problem of connection point welding.
3. About aluminum wire welding, there are terminal riveting, solder wire soldering, and some simply wrap the aluminum wire with copper wire and then solder. Aluminum enameled wire welding is specifically divided into two processes: one is paint removal and the other is welding.
A) Paint stripping. At present, many factories use the high-temperature tin of ironing. After ironing, the aluminum wire turns yellow and black, and cannot be soldered at all. Some paint strippers are used because of high-speed friction and high temperature. On the one hand, the diameter of the aluminum wire is damaged, and on the other hand, the surface of the aluminum wire becomes black and severely oxidized.
B) Connection method First, the terminal is riveted. The aluminum wire oxidizes quickly. Also, the potential for copper and aluminum is very different. Potential corrosion will gradually occur during the power-on process. The resistance of the connection point will gradually increase and the temperature rise will become higher. Finally, there will be no power. Solder to wire soldering is also very problematic. The temperature of the electric soldering iron cannot be very high, so it is easy to produce surfacing false soldering. The surface looks very full, but it is wrapped inside. Also, the flux cannot be vaporized in a short time. Therefore, there will be a lot of carbonized flux residue in the solder joint, and this method is unreliable through demonstration.
Copper leads clad aluminum welding, this method is self-deceiving, but the surface copper is tinned, and the aluminum inside is not tinned at all. Thinking about it, you will know how serious the problem is.
These are process issues. There are also material issues. Materials are also critical. Like aluminum fluxes, many of them on the market are acidic, which corrodes the aluminum wire itself seriously, causing the solder joints of aluminum motors and aluminum transformers to corrode and turn into powder after shipment.
3. Motors, including various household motors, fan motors, various micro motors, compressors, and other motors with high environmental requirements;
The commonly used method of aluminum enameled wire welding is to use a special flux-cored solder wire and solder with an electric soldering iron. Generally, aluminum enameled wire and aluminum enameled wire/bare aluminum wire/aluminum alloy/copper wire are suitable for welding. With this welding method (flame brazing can be used for wires, rows, and foils with large wire diameters or large areas), the workpieces welded by this welding method have good shape, reliable quality, and easy operation.