Introduction / Context:
Every manufactured dimension varies. Engineering drawings control that variation using tolerances. The statement describes tolerance as the total allowed spread between the maximum and minimum permissible sizes—a standard definition in both limit dimensioning and plus/minus practices.
Given Data / Assumptions:
- A dimension has specified limits (e.g., 10.00 +0.05 / -0.02) or a symmetric plus/minus (e.g., 10.00 ± 0.03).
- Manufacturing and inspection can achieve and verify these limits.
- Units and datum references are properly documented on the drawing.
Concept / Approach:
Tolerance = upper limit - lower limit. For 10.00 ± 0.03, tolerance = 0.06. For limit dimensions 10.05 / 9.98, tolerance = 0.07. This total variation ensures interchangeable parts even when produced by different lots, machines, or suppliers.
Step-by-Step Solution:
Extract upper and lower permissible sizes from the drawing callout.Compute tolerance as upper - lower.Confirm that the tolerance supports the required fit and function in the assembly.Align inspection gauges and sampling plans to these exact limits.
Verification / Alternative check:
Cross-check using a tolerance stack-up: if each contributor uses the stated total variation, the assembly requirement should still be met at worst case.
Why Other Options Are Wrong:
Incorrect: Conflicts with the accepted definition of dimensional tolerance.Only refers to surface finish / Applies only to metric: Tolerance applies to size and geometry in any unit system; surface finish is a separate specification.
Common Pitfalls:
Confusing tolerance with allowance (intentional fit difference between mating parts).Assuming measuring device resolution equals achievable tolerance.
Final Answer:
Correct
Discussion & Comments