Official Answer
Answer
Four numbers define the problem: the bore or shaft diameter, the axial space available, the load required, and the height at which that load must be delivered. From those, the geometry is calculated; operating stress is then checked at work height and again at solid height; fatigue is checked against the required cycle count; and only then is the material fixed against the environment. For a wave spring there is a fifth check that a coil spring does not need — radial wall and bore clearance. The spring grows in diameter as it flattens, and it must not bind against the bore. If the four numbers produce no workable geometry, that is itself a useful answer: the cavity has to change, not the spring.
