It is mainly used for automatic butt welding between fl at steel sheets. The welding method like TIG, MIG, MAG, and SAW can be used in welding process of carbon steel, stainless steel, aluminum and aluminum alloys, titanium and other materials. The technique is widely used in aerospace, automotive parts, motorcycles, home appliances, pressure vessels and food machinery fi elds. The Key-type pneumatic pressing device is applied to clamp the work piece. This device provides force evenly to work piece and prevents deformation.