Butt welding refers to the method that which the weldment is respectively placed between two clamping devices to make its end face aligned, and electric heating is applied at the contact point for welding. For butt welding, the cross-section size and shape of the contact part of the weldment shall be the same or similar, so as to ensure the uniform heating of the contact surface of the weldment. Butt welding is mainly used for manufacturing closed parts (such as bicycle rims, steel windows, etc.); Rolling material lengthening (such as steel town, steel pipe, steel bar, etc.); Welding of dissimilar materials (such as butt welding of dissimilar materials for saving valuable materials and improving the service life of tool working parts). The poly welding machine for sale is widely used because of its high productivity and easy automation.