1. The radius of the bending part. When forming leaf springs, most leaf springs must be bent. If the radius of curvature of the bending parts is relatively small, these parts will produce great stress. Therefore, in order to avoid large stress in the bending part, the bending radius should be at least 5 times of the plate thickness in design.

2. Stress concentration at the notch or hole. Leaf springs often have stepped parts and openings, and stress concentration will occur at the stepped parts with drastic size changes. The smaller the diameter of the hole, the larger the width of the plate and the greater the stress concentration coefficient.

3. Tolerance of spring shape and size. Leaf springs are mostly processed by stamping, and the shape and size suitable for stamping should be considered when designing. At the same time, the dimensional tolerances such as springback during bending and deformation during heat treatment should be fully considered.

The requirements for spring heat treatment should be based on the performance requirements, and the hardness after heat treatment can generally be determined between 36-52 HRC.