Due to product structure limitations, multi-strand springs generally have the characteristics of high strength and good performance. The material is required to guarantee the final performance in terms of spring strength and toughness. During the processing of multi-strand springs, it should be noted that: 1. The support ring can be cold-joined or hot-joined according to product requirements. The spring is not allowed to be heated to sparks or white when hot-joined, and the temperature of silicon-manganese steel shall not be higher than 850℃. The support ring and the effective ring should be in effective contact, and the gap shall not exceed 10% of the nominal gap between the rings. 2. The characteristics of multi-strand springs can be determined by adjusting the lead, and the cable length can be adjusted as necessary during winding. The twisting pitch can be 3 to 14 times the wire diameter, but generally 8 to 13 times is preferred. Its spring force is also closely related to the free height, end ring, outer diameter and wire performance, and can be changed by adjusting one or more of them. 3. Springs without support rings and springs with too thin wire diameters should not have their spring heads welded, but the end steel cables should not be obviously loose and should be deburred. For multi-strand springs that need to be welded at the head, the length of the welding part should be less than 3 times the rope diameter (the longest is not more than 10 mm). The heating length should be less than one circle, and the spring should be polished and smooth after welding. When gas welding, the welding part should be locally annealed at low temperature. 4. The surface treatment of the spring is generally phosphating treatment, and other treatments can also be performed. When the coating is zinc and cadmium, dehydrogenation treatment should be performed after electroplating. After dehydrogenation, 3% (not less than 3 pieces) should be extracted for retesting and standing treatment. There should be no breakage during the retest. The spring should be cleaned of surface dirt, salt marks, and oxide scale. The method can be sandblasting or gasoline cleaning, but pickling cannot be used. 5. The compression time of important springs is 24 hours, and that of ordinary springs is 6 hours or continuous compression 3 to 5 times, each time for 3 to 5 seconds. When compressing, the gap between the spring and the mandrel should be 10% of the mandrel diameter. If the gap is too small, it will be difficult to operate, and if the gap is too large, it will easily cause the spring to bend and deform. If one of the springs breaks during compression, the rest should be reprocessed.