With the increase of electrode pressure, the spot welder's R decreases significantly, and the spot welder's spot strength always decreases with the increase of welding pressure. The strength of the spot welder's welding point always decreases with the increase of welding pressure. The spot welding machine adopts the principle of double-sided double-point over-current welding, and the spot welding machine adopts the principle of double-sided double-point over-current welding. The spot welding machine has a current and time required for metals with different properties and thicknesses. The upper and lower limits, when the workpiece and the electrode are fixed, the resistance of the spot welder's workpiece depends on its resistivity. In order to obtain a certain strength of the welding spot, the spot welder can use high current and short time. ----Zhongbang Welding Machine