GD&T Tolerance Stack-up Analysis

Question 1

What is the primary purpose of tolerance stack-up analysis in GD&T?

Accepted Answer

To determine the worst-case variation in an assembly due to accumulated tolerances

Answer

Tolerance stack-up analysis determines how individual part tolerances accumulate to affect the overall assembly variation in the worst case.

Question 2

In a worst-case tolerance stack-up, how are individual tolerances combined?

Accepted Answer

They are arithmetically added, assuming all tolerances at their maximum

Answer

Worst-case analysis adds all tolerances arithmetically, assuming each feature is simultaneously at its maximum tolerance limit.

Question 3

What does RSS (Root Sum Square) analysis assume about the distribution of actual part dimensions?

Accepted Answer

Parts follow a normal (Gaussian) distribution

Answer

RSS analysis assumes part dimensions follow a normal distribution, which is typical for manufacturing processes under statistical control.

Question 4

Which type of tolerance stack-up analysis is more conservative and results in a larger required total tolerance?

Accepted Answer

Worst-case (arithmetic) analysis

Answer

Worst-case analysis is the most conservative because it assumes all tolerances simultaneously reach their extreme values, producing the largest possible variation.

Question 5

In a linear worst-case tolerance stack-up, what is the total gap variation if three dimensions each have a bilateral tolerance of ±0.1 mm?

Accepted Answer

±0.3 mm

Answer

In worst-case analysis, tolerances add arithmetically, so three ±0.1 mm tolerances accumulate to a total variation of ±0.3 mm.

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test

GD&T Tolerance Stack-up Analysis