What is metal fume?

The welding fume in welding operation includes smoke and dust. The metal vapor (such as A1, Mg, Cu, Fe, Zn, Mn, Si, Cr, Ni, etc., which are often included in the welding wire protective layer, weld area, base metal and fixture, etc., have boiling points lower than the arc column temperature) produced when the welding wire and the base metal melt rapidly condense and oxidize in the air to form solid particles with a diameter of less than 0.1 micron, which are called smoke, and metal particles with a diameter of 0.1-10 microns are called metal dust. They are collectively called metal fume.
The composition and concentration of metal fume depend on the welding process, welding materials and welding specifications. For example: from the perspective of welding methods, the amount of fume generated by brazing and cutting is less than that of open arc welding.

From the perspective of welding specification parameters: the welding current increases, the light emission increases, the arc voltage increases, and the amount of fume increases; the polarity of the power supply also affects the amount of welding fume; the amount of light emission varies with different welding positions. The light emission is larger in flat welding and the amount of fume is larger; the vertical welding is second.

What are the hazards of metal smoke to the human body? How to protect against it?
Long-term inhalation of high concentrations of welding smoke can cause a variety of serious organic changes in the respiratory system, nervous system, etc. For example, long-term inhalation of mixed smoke and harmful gases mainly composed of aluminum oxide, mixed with silicon dioxide, manganese, chromium, ozone, nitrogen oxides, etc., which are irritating and promote pulmonary tissue fibrosis, can cause "welder's pneumoconiosis". Long-term inhalation of trace materials and vapors of manganese and its compounds exceeding the allowable concentration can cause "manganese poisoning". Long-term argon arc welding in closed factories and welding workshops, inhalation of traces of aluminum oxide and fluoride can cause "welder's metal fever".
Therefore, when welding, measures must be taken, such as wearing masks, using dust collection equipment, installing ventilation devices, choosing low-dust welding wires, or using automatic welding instead of manual welding.