Estimate assembly variation from multiple component tolerances using worst-case or RSS
methods, then translate the result into capability impact. An optional Monte Carlo mode
simulates expected assembly variation under normal process behavior.
Analyzer
Enter component nominal values and bilateral tolerances
Core logic:
Worst-case = sum of tolerances, RSS = sqrt(sum of tolerance^2)
Use one component per line in the format: `Name, Nominal, +/-Tolerance`. The app assumes centered bilateral tolerances.
How to read the result
Worst-case is conservative and suitable when every tolerance can align in the same direction.
RSS is more realistic when component variation is random and centered, especially for mature processes.
Monte Carlo simulation assumes each component tolerance is approximately equivalent to +/-3 sigma unless actual process data says otherwise.
Components
Component contribution table
Component
Nominal
Tolerance
Worst-case share
RSS share
Simulation
Monte Carlo summary
Simulated mean: 47.750
Simulated sigma: 0.048
Observed simulated range: 47.570 to 47.935
Estimated out-of-spec rate: 0.02%
Instructions
How to use this app
Enter each component that contributes to the final assembly dimension, including its nominal
value and bilateral tolerance. The analyzer sums nominal values, computes worst-case and RSS
stack-up, and compares the selected result to the assembly specification.
Use worst-case when every tolerance must be guaranteed regardless of variation alignment.
Use RSS when component variation is random, centered, and reasonably stable.
The Monte Carlo option adds a probabilistic view. It treats each component tolerance as a
centered distribution and simulates repeated builds to estimate actual assembly spread and
likely spec escape.
