Leaf springs are widely used in electrical contact assemblies. Straight cantilever leaf springs with simple geometries are the most common type. Bronze is selected for contact‑type leaf springs to ensure low contact resistance. Measuring‑purpose leaf springs convert force or displacement. Provided the mounting structure and load setup keep the effective working length unchanged, leaf springs deliver constant stiffness within small‑deflection ranges. Non‑linear performance can also be achieved, for instance by letting the spring rest against limit plates or adjusting screws to alter its effective working length.
Characteristics of Leaf Springs
Leaf springs bend easily along one plane with low stiffness, while offering high tensile and bending stiffness in the perpendicular direction. This property makes leaf springs ideal for sensitive components, elastic supports, positioning units and flexible connections in measuring instruments and automatic equipment.
Introduction to Leaf Springs
A leaf spring is a simple spring element that generates spring performance via deformation of thin metallic sheets. Metal blanks can be rectangular, trapezoidal or triangular, and manufactured as straight or bent profiles. They are applied for low‑load, small‑deflection scenarios requiring moderate stiffness, such as sensitive components, elastic supports and positioning structures in instruments and automated machinery, including electrical switching contacts.
Classification of Leaf Springs
Leaf springs come in various shapes and configurations for different applications. By profile, they are divided into straight leaf springs and bent leaf springs. By sheet geometry, they fall into rectangular, trapezoidal, triangular and stepped types.
Technical Properties
Radius of bent sections
Most leaf springs undergo bending during forming. Small bending radii create high local stress. To avoid excessive stress, the bending radius shall be at least five times the sheet thickness in design.
Stress concentration at cut‑outs and holes
Leaf springs often feature steps and cut‑outs. Sharp dimensional transitions cause stress concentration. Smaller hole diameters paired with larger sheet widths result in higher stress‑concentration
Dimensional tolerances for geometry
Leaf springs are mostly produced by stamping. Designs shall suit stamping processes. Tolerance allowance shall account for spring‑back after bending and thermal deformation during heat treatment. Heat‑treatment requirements shall be defined according to operating conditions. Typical hardness after heat treatment ranges from 36 HRC to 52 HRC.