⚠ Worst-case stack exceeds specification limit on one or more axes.
Study setup
Use angular acceptance criteria
Enable LSL / USL and Cp/Cpk for Rx, Ry, and Rz only when orientation itself is a functional requirement.
Axis
LSL ?Lower Specification Limit. The smallest acceptable dimension for the final assembly to function correctly.
USL ?Upper Specification Limit. The largest acceptable dimension for the final assembly to function correctly.
Stack elements
0 rows
Each element contributes to one or more axes. For rotational axes (Rx/Ry/Rz), enter the moment arm, which is the perpendicular distance from the rotation centre to the point of interest.
Quick examples
Linear 1DPlanar XYFull 3D + rot
Stack-up
Axis
Nominal ?The arithmetic sum of all nominal dimensions. This is the assembly dimension if all features are produced exactly at their nominal size.
WC min ?Worst-Case Minimum = Σ(nominal − tol−). Every feature simultaneously produced at its smallest extreme limit. Independent of process capability.
WC max ?Worst-Case Maximum = Σ(nominal + tol+). Every feature simultaneously produced at its largest extreme limit. Independent of process capability.
RSS min ?Statistical lower bound. Displays the assembly dimension at −Nσ from nominal (N is your Confidence Interval selection).
RSS max ?Statistical upper bound. Displays the assembly dimension at +Nσ from nominal (N is your Confidence Interval selection).
σ combined ?σ_combined = √Σσᵢ². RSS (Root Sum of Squares) of individual component standard deviations. This predicts the true assembly variation.
Cp ?Cp = (USL − LSL) / 6σ. Process potential: how many times the natural 6σ spread fits inside your LSL→USL limits. Doesn't care about centering.
Cpk ?Cpk = min((USL − μ)/3σ, (μ − LSL)/3σ). Actual process capability. Accounts for how well the assembly nominal is centered between the LSL and USL.
