Answer
When a wave spring is axially compressed, its wave height decreases, causing the flat wire to expand outward radially. This radial growth must be strictly accounted for to prevent the spring from binding inside a housing or interference with an internal shaft.
Theoretical Expansion Calculation:
$$D_{max} = \sqrt{D_m^2 + \left( \frac{1.45 \cdot h \cdot N_w^2}{\pi} \right)^2} + \frac{b}{2}$$
Where $h$ is the wave amplitude ($mm$), $N_w$ is the wave count, and $b$ is the radial wall width.
Engineering Management Guidelines:
1. Groove / Housing Clearance: Always design the housing inside diameter ($D_{housing}$) larger than the calculated maximum expanded spring outer diameter plus a safety margin of at least $0.15\text{ mm}$:
$$D_{housing} \ge D_{max} + 0.15\text{ mm}$$
2. Shaft Clearance: For shaft-mounted applications, ensure the inner diameter of the wave spring at solid height does not constrict or lock onto the shaft. Keep a minimal inner clearance of $0.1\text{ mm}$ to $0.25\text{ mm}$ at maximum axial deflection.
