In the precision manufacturing workshop of a domestic ordnance factory, the low rumble of air compressors once lingered constantly. Multiple constant-frequency screw air compressors operated around the clock in a high-pressure and low-efficiency mode, delivering stable air supply for precision processing yet consuming massive power. The adoption of Kelupp permanent magnet variable-frequency oil-free screw blower system has reduced workshop noise by 15 decibels and achieved an annual power saving rate of over 32%. It has set an exemplary model for energy-saving upgrading in the military manufacturing sector, enabling the shift to green energy while guaranteeing the manufacturing precision of national key equipment.