(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 :
$$T_assy = \sqrt0.20^2 + 0.10^2 + 0.15^2$$ $$T_assy = \sqrt0.04 + 0.01 + 0.0225$$ $$T_assy = \sqrt0.0725$$ $$T_assy = 0.269 \text mm$$ 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 . The standard RSS formula assumes a perfect normal
(17.00 \pm 0.27) mm
$$T_assy = \sqrt\sum_i=1^n (C_i \cdot T_i)^2$$ manufacturing processes drift.
Where is a correction factor (typically 1.2 to 1.5 ), or using the Benderization method:
You can use this content for a blog post, training manual, or engineering reference. 1. What is RSS Tolerance Analysis? Root Sum Square (RSS) is a statistical method used to predict the overall variation in an assembly (a "stack-up") based on the tolerances of its individual components.