What is micro welding?

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The term “micro welding” refers to the precise placement of connective metals and the application of energy to form welds that are less than 100 micrometers wide. Typically performed under a microscope for accuracy, the actual welding process in some cases exactly mimics normal welding, simply on a much smaller scale. In most high-volume industrial environments, microwelding is automated, requiring little skill on the part of the operator, but some special or irregular welds require a highly trained technician with a very steady hand. Because it is such an exact and complicated process that it involves specialized tools, most work is outsourced to specialists.

Resistance microwelding is the most basic method and is used to join flat plates of various metals. The two plates are slightly overlapped and the welding electrodes are placed on each side of the overlap. An electrical current is applied to heat the metal to the molten state, and the electrodes channel this current from one to the other through the overlap. As the metal cools, it bonds together to form a permanent bond. The strength method is used to join small seams where the joint must be perfectly flat, such as in medical implants.

Flash microwelding is used for small butt joints, such as wire or jewelry, and is done by heating the end of each piece with an electrical current and clamping them together. The process produces a steep temperature gradient along the axis of the part, allowing a wide variety of materials and shapes to be joined together without deforming. The most versatile of all microwelding operations, it produces sparks, so it is not suitable for flammable or temperature sensitive materials.

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Micro arc welding is used to join two parts of any shape, usually with the help of a filler material that is placed along the weld site to act as glue. An electrical current is applied to an electrode that is conducted along the weld site, which heats the base metal and filler metal until they mix to form a new metal. As the place cools, the parts and filling are inextricably matched. This method is used to make accurate repairs to metal molds and tools, especially when parts are chipped or worn and need to be rebuilt.

Laser microwelding is typically what is used in automated industrial environments. The laser can be controlled as tightly as needed and can hit difficult places that other welding methods cannot, heating the metal almost instantly and requiring no filler or pressure to create the perfect joint every time. The laser method can also be used to engrave metals, although shiny surfaces may need to be pre-treated to prevent reflection of laser light.

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