GD&T GD&T ASME Y14.5 Standards and Drawing Interpretation

Question 1

Which standard governs GD&T practices in the United States?

Accepted Answer

ASME Y14.5

Answer

ASME Y14.5, published by the American Society of Mechanical Engineers, is the U.S. standard defining GD&T symbols, rules, and practices.

Question 2

What does Rule #1 (the Envelope Principle) state in ASME Y14.5?

Accepted Answer

A feature of size's surface must not violate a perfect-form envelope at MMC

Answer

Rule #1 requires that a feature of size controlled only by size tolerances must not violate a perfect-form (zero geometric error) boundary when the feature is at MMC.

Question 3

What is a 'feature of size' as defined by ASME Y14.5?

Accepted Answer

A feature with directly opposed elements — such as a cylinder, hole, or two parallel surfaces — definable by a single size dimension

Answer

A feature of size has directly opposed surfaces or elements that can be measured across a single dimension, enabling MMC and LMC modifiers to apply.

Question 4

What does ASME Y14.5 Rule #2 establish?

Accepted Answer

Unless otherwise specified, all geometric tolerances apply at RFS (Regardless of Feature Size)

Answer

Rule #2 makes RFS the default condition — if no modifier is shown in the feature control frame, the geometric tolerance applies at all feature sizes.

Question 5

What major new symbol was introduced in the ASME Y14.5-2018 revision?

Accepted Answer

The Independent modifier (encircled I), which overrides Rule #1 for a specific feature

Answer

ASME Y14.5-2018 introduced the Independent modifier (Ⓘ), which explicitly releases a feature from Rule #1's perfect-form-at-MMC requirement.

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

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

GD&T GD&T ASME Y14.5 Standards and Drawing Interpretation