What is flash welding?

Flash welding is a butt welding in which metal surfaces are fused together by an electric current.

Due to the conductive properties of metals, current can pass through when there is a small gap between the workpieces. This, in turn, creates local sparks or “arcs” that quickly heat the metal.

Workers then press the parts together to create a bond between the metal surfaces.

How does flash welding work?

Flash welding works by applying an electric current to the necessary metals to form a bond. The metal itself acts as a conductor, allowing the current to flow; This process generates a lot of heat. The resulting heat is enough to fuse the metals together to form a weld.
Flash welding is unique in its application because it requires you to pass a current while there is still a small gap between the sheet metal. The gaps are small enough to allow electric current to arc between them, creating heat in the two metal sheets. The heat generated is enough to soften and often melt the surface of the metal to which it is attached.
It is at this point that the worker forces the two metals together, forming a strong and secure union.
Once the right temperature is reached, the current is turned off and the worker waits for the weld to cool.
Why do we see “flashes”? During flash welding, small contacts between two pieces of metal produce localized areas of high current density. The characteristic flash occurs when an electric current heats, melts, and burns off impurities in the metal.

What are the benefits of this process?

Typically, you would use flash welding on anything that can be clamped and slowly put together. This allows connections to be made on parts of various shapes and sizes. Railway tracks and car rims are common applications of the process.
This method does not require caulk and workers do not need to prepare the surface beforehand, reducing overall complexity.
As the arc occurs and heat is generated, any impurities at the welding site are burned off in the flash, creating a strong and reliable connection.
Finally, different metals can be connected, including ferrous and non-ferrous metals.

What are the restrictions?

The most obvious drawback is the electric arc and flash generated during the process. This is a potential fire hazard waiting to happen and requires careful management of each weld.
Every flash produced is hot metal — metal lost during welding. The metal ends up as a flash product at the welding site, which needs to be cleaned manually.
Finally, flash welding requires heavy welders. This limits work to specialized workshops or specially designed equipment.

What are the health hazards of flash welding

1. Eye injury:
(1) A thermal cataract caused by infrared radiation from molten metal, resulting in blurred vision;
(2) Arc eyes caused by ultraviolet radiation emitted during the process, resulting in eye pain and watery eyes;
(3) Other injuries, such as corneal ulcer and conjunctivitis caused by external substances (slag, cutting sparks, etc.);
(4) Skin irritation and redness caused by excessive exposure to radiation;
2. Inhale the following fumes or gases generated during the process:
(1) Smoke of nascent metal oxides, causing metal fever;
(2) Toxic metal fumes such as lead, cadmium, beryllium, etc.;
(3) Bronchial and lung irritation caused by toxic gases such as nitrous oxide and fluoride;
(4) burned by the flame of the blown pipe, hot slag or workpiece surface;
(5) Physical injury caused by manual handling of gas cylinders or large workpieces.
3.Physical injury caused by manual handling of gas cylinders or large workpieces.

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