Official Answer
Answer
When a wave spring is used in a housing made of a relatively soft material like aluminum (e.g., 6061-T6), the concentrated loads at the wave crests can cause 'brinelling' or localized indentation. This increases the effective work height and reduces the spring preload over time. To prevent this, a hardened steel load washer (typically RC 40-45) is placed between the spring and the aluminum surface. The washer distributes the load over a larger area. The thickness of the washer must be accounted for in the total stack-up height calculation: $H_{total} = H_{spring} + t_{washer}$. In high-vibration automotive environments, this is a standard practice to prevent wear-induced loss of tension in belt tensioners or clutch packs.
