Official Answer
Answer
The natural frequency $f_n$ is critical to prevent valve float. It is given by $f_n = \frac{1}{2 \pi} \sqrt{\frac{K}{m}}$, where $K$ is the spring rate and $m$ is the effective mass. For a wave spring, $m \approx \frac{1}{3} m_{spring} + m_{valve}$. If the operating frequency approaches $f_n$, the spring will undergo uncontrolled oscillations, leading to fatigue failure. By using 17-7PH CH900 material, we can increase $K$ for a given mass compared to standard carbon steels, shifting the natural frequency higher and out of the engine's primary harmonic range.
