To ensure the printing quality of the SMT printing machine and avoid contamination of the PCB surface with residual solder paste and solder powder from the stencil and screen, it is necessary to regularly and fixedly wipe and clean the bottom of the printed steel stencil to avoid solder paste contamination of the board surface, avoid solder beads on the board surface after welding, and ensure technical indicators such as the form, shape, and amount of solder paste for printing.