... spring 2.fully-automatic spring production Black steel constant force Flat spiral spring Flat spiral coil springs are manufactured ... a gap between the coils(power springs and constant-force springs)are mainly integrated into housings and held in ... wire), bronze, copper, phosphorus copper, beryllium copper. Alloy steel has 60Si2MNA, 60Si2CRVA, 55CrSiSurface treatment plate gold, silver, white, red ...