Welders join metal parts by applying intense heat. The heat melts the metal into a liquid, which then solidifies.
The welder may have to adjust the parts to be welded on a workshop bench, or directly on a construction site. They hold the metals together using templates and apply the welds.
Welders can use manual or mechanized techniques. They typically use an electric arc (the bright, hot area between the tip of the electrode and the metal) or a gas flame to melt the metal. For the manufacture and production of electrical resistance they can use high energy beams (such as electron beams and laser beams) or friction beams.
There are four main manual welding processes. In the manual metal arc welding, welders use an arc between the metal rod and the workpiece, and the two fuse to form a weld pool. The rod cover melts to form gas and a by-product of the welding process, which protects the weld pool until it has cooled.
The oxyacetylene welding it relies on the combustion of oxygen and acetylene (a type of gas) to form a very hot flame.
In the metal inert gas welding, welders use an inert gas (a gas that does not react with any other substance) to protect the arc and weld puddle.
In the tungsten welding, similar to an inert gas, they use tungsten to join magnesium, aluminum, stainless steel and titanium.
Welders follow technical drawings or instructions, and look for the best position and angle to take for work (kneeling, sitting, standing, or lying down).
They can rehearse a difficult weld and the movements they must make to make sure they can hold position while working. First, the surface to be welded is prepared and cleaned. They adapt the welding torch nozzle or the appropriate electrode, adjust the current, connect and ignite the arc, and begin welding.
Welds can be horizontal or vertical, at an angle, in a bend, or around a large tube. Welders can work from above, from the side, or from under the weld, and sometimes in very uncomfortable and tight places.
Safety is vital to brazing, so there are inspectors who can check welds made by using X-rays, ultrasound, or staining tests. If they discover cracks, porosity, or other errors, the welders have to reinforce the weld or redo the job.
In addition to manual techniques, some types of welding are mechanized or done by robots, especially in industries that produce large-scale items, such as the motor industry.
There, the technicians set up the machines that are then controlled by the welders. There are other more specialized welding processes such as resistance welding, laser welding, electron beam welding, and solid state welding.
Welders wear protective clothing (helmet, overalls, boots, aprons, gloves, and tinted glasses). The environment can be very noisy, so welders may need protective headphones.