Podcast
Questions and Answers
What is concentricity in GD&T?
What is concentricity in GD&T?
- A measure of how closely a feature is aligned with a datum plane
- A 3-Dimensional cylindrical tolerance zone defined by a datum axis (correct)
- A tolerance that ensures a feature is symmetrical about a datum axis
- A tolerance that ensures all points on a feature are equidistant from a datum axis
What must be true for a cylindrical feature to meet the concentricity tolerance?
What must be true for a cylindrical feature to meet the concentricity tolerance?
- The feature must be coaxial with the datum axis
- The feature must have a constant diameter along its length
- The feature must be perfectly circular in cross-section
- All median points along the entire feature must be within the tolerance zone (correct)
What is the primary purpose of position tolerances in GD&T?
What is the primary purpose of position tolerances in GD&T?
- To control the form of a feature
- To control the size of a feature
- To control the orientation of a feature
- To locate features from datums or establish coaxiality or symmetry (correct)
What does a position tolerance define?
What does a position tolerance define?
What is the 'true position' in GD&T?
What is the 'true position' in GD&T?
What is symmetry in GD&T?
What is symmetry in GD&T?
If a feature meets the symmetry tolerance, what can be inferred?
If a feature meets the symmetry tolerance, what can be inferred?
What is the relationship between concentricity and symmetry tolerances?
What is the relationship between concentricity and symmetry tolerances?
If a position tolerance is given, what does it NOT control?
If a position tolerance is given, what does it NOT control?
What tolerance would be used to ensure two holes are coaxial?
What tolerance would be used to ensure two holes are coaxial?
Study Notes
Geometric Dimensioning and Tolerancing (GD&T)
Form and Profile Controls
- 14 characteristics that may be controlled, including:
- Flatness
- Straightness
- Circularity
- Cylindricity
- Line Profile
- Surface Profile
Form Controls
- Flatness: a perfectly flat surface must contain all elements in one plane
- Straightness: an element of a surface or an axis is a straight line
- Circularity (roundness): all points of the surface intersected by any plane perpendicular to a common axis are equidistant from the axis
- Cylindricity: controls the surface of a cylinder, including parallelism of the sides
Profile Controls
- Line Profile: controls single line elements on a feature, each element is independent of all others
- Surface Profile: controls all elements on a feature, simplest level of control, controls form only
Orientation, Runout, and Location Controls
- 14 characteristics that may be controlled, including:
- Perpendicularity
- Angularity
- Circular Runout
- Total Runout
- Concentricity
- Position
- Symmetry
Orientation Controls
- Perpendicularity: two parallel planes of cylindrical zones that are perpendicular to a datum plane
- Angularity: a surface, center-plane or axis at a specified angle (other than 90°) form a datum plane or axis
- Parallelism: two parallel planes of cylindrical zones that are parallel to a datum plane
Runout Controls
- Circular Runout: controls circularity and concentricity, measured by rotating the part 360°
- Total Runout: controls cumulative variations of circularity, straightness, coaxiality, angularity, taper, and profile of a surface
Location Controls
- Concentricity: a 3-Dimensional cylindrical tolerance zone defined by a datum axis
- Position: locates features from datum’s or establishes coaxiality or symmetry
- Symmetry: median points of all opposed or correspondingly-located elements of two or more feature surfaces are coincident with the axis or center plane of a datum feature
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Description
Test your knowledge of Geometric Dimensioning & Tolerancing (GD&T) concepts with this quiz. Explore topics such as form, profile, characteristic controls, feature types, and tolerance symbols.
