Welding, also known as welding, is a manufacturing process and technology for joining metals or other thermoplastic materials such as plastics by heating, high temperature, or high pressure. There are many energy sources for modern welding, including gas flames, electric arcs, lasers, electron beams, friction and ultrasonic waves. In addition to being used in factories, welding can also be carried out in a variety of environments, such as the field, underwater and space. No matter where it is, welding may bring danger to the operator, so appropriate protective measures must be taken when welding. The possible harm to the human body caused by welding includes burns, electric shock, visual impairment, inhalation of toxic gases, excessive ultraviolet radiation, etc.