Self-tapping screws can directly cold-extrude internal threads within plain holes, thereby achieving an interference fit without the need for pre-tapped threads. This eliminates the process of pre-tapping, reduces fastening time, improves assembly efficiency, and lowers production costs. Furthermore, self-tapping locking screws feature a low driving torque requirement.
Self-tapping screws offer superior locking performance and anti-loosening capabilities, with locking torque increased by 50% to 60%. For instance, the locking effect can be further enhanced-and loosening caused by vibration prevented-by incorporating interlocking washer structures or by utilizing serrations on the underside of the screw head that interlock with external-tooth locking washers.
Self-tapping screws are characterized by high surface hardness combined with excellent core toughness-a quality often described as being "hard on the outside, tough on the inside." The surface hardness typically exceeds 45 HRC, while the core toughness is maintained within the range of 28 to 39 HRC. For high-performance self-tapping locking screws, the surface hardness in critical areas-such as the lead threads-can reach over 56 HRC, enabling them to cold-extrude threads directly into workpieces with a surface hardness exceeding 23 HRC.
