Seamless welding may be employed depending on the type of gas, gas welding specific situation, there is used a shielding gas carbon dioxide, argon, helium, hydrogen, and mixed gases. GMAW advantages are: linear arc good, easy, easy to implement all-position welding and automatic welding; arc heat concentrated, small bath, welding speed, heat-affected zone is narrow, weldment distortion, cracking capacity Strong and good weld quality. The disadvantage is not on a windy site welding, arc light radiation is strong. 

Seamless welding technology, welding device is a function of the device through a transistor current electricity 50/60Hz frequency 20KHz or 40KHz into a high-frequency electric power supply to the converter. Mechanical vibration welding head is directly transferred to an acoustic device requires lamination products. Vibration friction generated heat can melt plastic welding work pieces pass through the adhesive surface vibration, but its strength is close to a piece of welding material attached . 

Seamless welding technology, not only can help eliminate mold seam, but also a corresponding increase in the accuracy of parts, finish and appearance of observability. Meanwhile, the seamless welding technology in the injection molding process, the implementation of effective control, shortening the mold processing cycle. Because of the technology products with excellent surface finish, so no use of secondary deposition and annealing, thus avoiding the dimensional changes caused by secondary contraction. 

The new seamless welding technology uses a modern machine tools and some new technology. A process according to requirements of the new technology, the processing of the mesh-like mold core and cavity, and in order to avoid moving the second clamping, using a fourth axis milling machine, which can improve the accuracy tolerances. Room cooling fins, and water pipelines board has also been more widely used, and further improve product quality and seamless weld finish.