Molybdenum spot welding head is composed of two pieces of metal with good conductivity. The center of the two pieces of metal is insulated. As long as there is a contact at the tip, this contact forms a very small resistance. The bottom end of the welding head is flat and lubricated. When operating the machine, when using pneumatic means or using a foot pedal to press the molybdenum spot welding head onto the enameled wire, the pressure will continue to increase. When the reaction force between the enameled wire and the welding head reaches the set welding pressure, a pulse current will be triggered. The current duration is very short, usually between a few milliseconds to more than ten milliseconds, with a size of about tens to over a hundred amperes. The current flows through the bottom of the welding head, There is a contact resistor at the tip of the solder joint, which generates heat and sparks in the area of contact. This heat can remove the paint from the enameled wire and a large amount of heat will be transferred to the copper wire inside the enameled wire. At the same time, a portion of the current will flow through the copper wire that has been burned off from the bottom of the solder joint, and the copper wire itself is also heating. The melting state of the copper wire before the temperature reaches the melting point in a short period of time, Under the action of pressure, a new molten core is formed with the metal underneath, which connects the enameled wire to the metal substrate.
Molybdenum has extremely low Vapor pressure under the operating temperature and pressure of vacuum furnace. Therefore, molybdenum parts have relatively little pollution to furnace workpieces or working materials, and transpiration loss will not necessarily constrain the service life of molybdenum high quality parts such as heating elements and insulation packages. The high strength of molybdenum in the production of glass products makes it an ambitious electrode and processing and processing equipment during rapid heating. Molybdenum is chemically compatible with most glass components, and it will not cause harmful chromogenic effects due to the dissolution of a small amount of molybdenum in the glass melt. As a heating electrode in a glass melting furnace, its lifespan can reach up to 3-5 years, and the technological content of molybdenum products is constantly improving, leading to the widespread application of molybdenum products.
In addition to its high strength, good conductivity, heat conduction and low coefficient of thermal expansion (similar to the glass used for electronic tubes), molybdenum and molybdenum alloys have the advantage of being easier to process than tungsten. Therefore, the plates, strips, foils, tubes, rods, wires and profiles produced by conventional processing methods are used in electronic tubes (grids and anodes), Electric light (supporting data), Metal processing tools (die-casting and kneading molds, forging molds, piercing plugs, liquid metal filter screens) and turbine discs are widely used in components.