The single-die multi-channel production process is abandoned for filter housing, threaded cover, sealing cover, filter cover and other hardware parts by using automatic mold one-time forming production process to ensure the precision of metal parts stamping processing in order to meet product quality needs. The connecting thread adopts the automatic tapping equipment combined with the squeeze tapping process to effectively ensure the verticality of the thread and the surface smoothness of the screw. The housing adopts spray-type automatic phosphating process to effectively improve the rust-proof performance and internal cleanliness. The surface of the filter adopts high-pressure electrostatic powder spraying process to make the powder evenly distributed on the surface of the shell. After high-temperature leveling, it produces strong adhesion, so that the outer surface of the shell is effectively protected. Finished product assembly adopts high-precision automatic sealing equipment and shell first powder spraying and then edge sealing technology to ensure stable and reliable product sealing quality, and avoid aging deterioration of filter element if secondary baking.