Official Answer
Answer
Shim ends, also known as 'flat ends,' are produced by flattening the last half-wave on each end of a multi-turn spring. This creates a $360^{\circ}$ contact surface rather than point contact at the peaks. This is critical for applications where the spring must provide uniform pressure on a seal or a bearing race. While shim ends increase the solid height $H_s$ by $2t$, they significantly reduce the 'tipping' moment and ensure that the load is transmitted axially. The spring rate calculation must be adjusted because the shim ends act as inactive turns, reducing the effective number of active waves.
