Abstract: A plastic welding machine, especially a hot air or hot wedge sealing machine, for connecting in a material fit at least two layers (38, 39; 43, 44; 48-50). The welding machine (1) comprises welding tools (7), at least one pair of driving rollers (8, 9) each, and an electronic control device (2) including a computer (3) for controlling the temperature of the welding tools (7) and for adjusting and regulating the pressure of the driving rollers (8, 9). A welding machine is provided wherein the welding process can be sequence-controlled substantially independently of the respective operator of the welding machine (1). For this purpose, the sequence control of the welding process is carried out without intervention of the operator only using a sequence program (welding program) stored in a memory (35) of the electronic control device (2).