$$T_assy = \sqrt0.20^2 + 0.10^2 + 0.15^2$$ $$T_assy = \sqrt0.04 + 0.01 + 0.0225$$ $$T_assy = \sqrt0.0725$$ $$T_assy = 0.269 \text mm$$
(0.20 + 0.10 + 0.15 = \pm 0.45) mm RSS gives a 40% tighter assembly tolerance than worst-case. 4. Modified RSS (Adjusted for Process Capability) In reality, manufacturing processes drift. The standard RSS formula assumes a perfect normal distribution. To account for this, engineers use Modified RSS : rss method tolerance analysis
Unlike the worst-case (linear) method which adds all tolerances arithmetically, RSS assumes that not all components will be at their extreme limits simultaneously. It is based on the statistical principle that variations follow a . $$T_assy = \sqrt0