Friction stir welding is a special kind of welding that does not use heat .
In robot welding , mechanized devices both hold the material and perform the weld and at first , spot welding was its most common application , but robotic arc welding increases in popularity as technology advances . Other key areas of research and development include the welding of dissimilar materials ( such as steel and aluminum , for example ) and new welding processes , such as friction stir , magnetic pulse , conductive heat seam , and laser-hybrid welding .