How do the thread angle and pitch of Stainless Steel Self Tapping Screw affect their self-tapping performance?

1. The influence of thread angle
The thread angle usually refers to the angle of the thread profile. The common thread profile angle of Stainless Steel Self Tapping Screw is 60° or 30°-45°. Different thread angles directly affect the cutting ability and load-bearing performance of the screw. Small-angle threads are sharper and can cut into hard materials more easily, reducing the torque required for assembly. This design is particularly suitable for self-tapping of high-hardness materials, but the strength of the thread itself is low, and deformation or slipping may occur under high loads. Large-angle threads are relatively flat and have weaker cutting forces, but the thread contact area is larger and can provide stronger load-bearing capacity. This design is more suitable for soft materials and can reduce the risk of material cracking.

Small-angle threads have a larger axial component force and can generate a stronger radial clamping force, thereby improving the anti-loosening performance and being suitable for vibration environments. Large-angle threads have a wider lateral contact surface and are suitable for occasions requiring high tensile strength, but the anti-loosening performance is relatively weak, and additional anti-loosening measures may be required.

2. Effect of pitch
The pitch refers to the distance between adjacent thread peaks, and is usually divided into coarse and fine pitch. The choice of pitch directly affects the assembly speed and mechanical properties of self-tapping screws. Coarse-pitch screws have a larger feed rate per rotation, which can complete drilling and tapping faster and are suitable for soft materials (such as plastics and wood). However, due to the shallow thread depth, their tensile strength and anti-loosening properties are relatively weak. Fine-pitch screws have denser threads and can form a tighter bite with the material, which is suitable for hard materials (such as stainless steel and steel), providing higher tensile strength and anti-loosening properties. However, fine-pitch screws require greater assembly torque and have a slower tapping speed.

Coarse-pitch screws can reduce the risk of material cracking because their force per unit area is more dispersed, which is suitable for fast assembly. Fine-pitch screws can better form threads, avoid slipping or thread stripping, and ensure the reliability of fastening.

3. Synergy between thread angle and pitch
The thread angle and pitch do not act independently, but cooperate with each other to jointly affect the performance of self-tapping screws. For hard materials, a combination of small thread angle + fine pitch is recommended to enhance cutting ability and improve tensile strength. For soft materials, a combination of large thread angle (60°) + coarse pitch is recommended to increase assembly speed and reduce material damage.

Analysis of extreme cases
If the pitch is too large and the thread angle is too small, the thread strength may be insufficient and it may break easily during assembly. If the pitch is too small and the thread angle is too large, the self-tapping performance will decrease, and pre-drilling may still be required, which cannot give full play to the advantages of self-tapping screws.