1. Under what circumstancesMotorHot tin
Because multi-strand wires are easy to loose, the contact area will be reduced when pressed on the terminal. Therefore, when the multi-strand wires need to be pressed in a place with high current, the tin must be hot to avoid poor contact and heat and burn.
The melting point of tin is very low, only 232℃
Tin is afraid of cold and heat.At different temperatures, tin has three forms with very different properties.In the temperature range of -3 to 13.2°C, tin has the most stable properties and is called "white tin".If the temperature rises above 161°C, white tin will become "brittle tin" that breaks at the touch of a touch.
The role of "hot tin" on the terminal
We all know that the resistance of the conductor will heat the conductor under the action of the current. The larger the current, the higher the heat generation. The function of the tinning process is to reduce the heat generation.A layer of tin film with a lower melting point will be formed after the terminal head is "hot tinned". When such a wire head is used to press the wire nose, the tin film will melt under the high pressure of the hydraulic crimping tool, and fully fill the wire and At the same time, the melted tin will infiltrate the inner wall of the wire nose. These two effects minimize the contact resistance of the press-fitted wire head and the heat generation, which is not easy to cause accidents. At the same time, it is extended Service life.
The welding of wiring is divided into many kinds of the most commonly used: solder connection, welding connection, and brazing connection.
Brazing process
In the silver-based brazing process, the operation process is very important, among which the control of the heat is the most important, it is more directly related to the production efficiency and product quality.
According to experience, the welding torch needs to be about 30-40mm away from the weldment during brazing. At the same time, the flame should be slightly swayed around the surface to be welded, so that the firepower is slightly dispersed instead of concentrated at one point, so as to avoid the weldment due to the concentration of firepower. Partially melted.Add the solder after the surface to be welded is evenly heated to the brazing temperature, otherwise the solder will not fill the gap uniformly.According to experience, the product turns red after being heated, and when the surface to be soldered turns dark red, the solder must be placed above the interface so that it can flow quickly along the interface.If the solder is placed before the solder turns dark red or after it turns dark red, there will not be a good welding effect, and there will be defects.
Heating rate and cooling rate are also important process parameters during brazing.Too fast heating will cause uneven internal temperature of the weldment and generate thermal internal stress; too slow heating will cause certain harmful processes, such as material grain growth, metal oxidation, and flux decomposition.It is necessary to shorten the heating time as much as possible while ensuring uniform heating.Although the cooling of the weldment is after the brazing process, its cooling rate also has an impact on the quality of the joint. Too high cooling rate may cause the weldment to crack due to excessive thermal force, or the brazing seam may cause excessive solidification. The gas is too late to escape and creates pores.
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