When welding rail tracks, the perpendicularity of the rail ends is the primary factor in achieving a quality joint. The contact surface between the rail and the electrode is a critical factor. The voltage of the generator is also one of the influencing factors; the water temperature of the chiller and the cooling degree of the welding machine's head also affect stability; the temperature of the rail to be welded also impacts welding quality. The oil pressure of the oil pump and the welding head is also an influencing factor, and the stability of 4DA and 4AD will also have an impact.  

If the welding quality changes, you should pay attention to these factors.