Podcast
Questions and Answers
What does a straightness tolerance control on a surface?
What does a straightness tolerance control on a surface?
- The curvature of the surface.
- The conicity of the cylinder.
- The centreline of the surface.
- The bending or wavy condition of the surface. (correct)
What would a straightness tolerance on a conical surface ensure?
What would a straightness tolerance on a conical surface ensure?
- Uniform rate of taper. (correct)
- Equal radius along the length.
- Constant curvature.
- Circular cross-sections.
What is circularity a condition of?
What is circularity a condition of?
- A circular line or surface. (correct)
- An elliptical cross-section.
- A cylindrical feature.
- A spherical shape.
What is the result of a circularity error?
What is the result of a circularity error?
What is required to control the rate of taper on a conical surface?
What is required to control the rate of taper on a conical surface?
What direction does a straightness tolerance on a flat surface control?
What direction does a straightness tolerance on a flat surface control?
What is required when the same straightness tolerance is required in two coordinate directions on the same surface?
What is required when the same straightness tolerance is required in two coordinate directions on the same surface?
How can multiple straightness tolerances be shown on a single view?
How can multiple straightness tolerances be shown on a single view?
What is the primary purpose of a circularity tolerance?
What is the primary purpose of a circularity tolerance?
What is the term for the random irregularities from a true circle in a circular feature?
What is the term for the random irregularities from a true circle in a circular feature?
On what basis is a circularity tolerance expressed?
On what basis is a circularity tolerance expressed?
What is the minimum radial separation between two concentric circles within which all points on the measured surface shall lie?
What is the minimum radial separation between two concentric circles within which all points on the measured surface shall lie?
What is the limitation of measuring circularity?
What is the limitation of measuring circularity?
What is the relationship between the circularity tolerance and the size tolerance?
What is the relationship between the circularity tolerance and the size tolerance?
What is the term for the differences between the major and minor axes of a circular feature?
What is the term for the differences between the major and minor axes of a circular feature?
What is the purpose of the concentric circles in assessing circularity?
What is the purpose of the concentric circles in assessing circularity?
What is a geometric tolerance?
What is a geometric tolerance?
What is the purpose of a feature control frame?
What is the purpose of a feature control frame?
What is straightness?
What is straightness?
Where is a straightness tolerance applied?
Where is a straightness tolerance applied?
What is the purpose of a tolerance zone?
What is the purpose of a tolerance zone?
How is a straightness tolerance specified on a drawing?
How is a straightness tolerance specified on a drawing?
What is the shape of a tolerance zone for a straightness tolerance?
What is the shape of a tolerance zone for a straightness tolerance?
For cylindrical parts or curved surfaces, where should the feature control frame be directed?
For cylindrical parts or curved surfaces, where should the feature control frame be directed?
Study Notes
Geometric Tolerancing
- Geometric tolerance is the maximum permissible variation of form, profile, orientation, location, and runout indicated or specified on a drawing.
- The tolerance value represents the width or diameter of the tolerance zone within which the point, line, or surface of the feature shall lie.
Straightness Tolerance
- Straightness is a condition in which the element of a surface or centerline is a straight line.
- A straightness tolerance specifies a tolerance zone within which the considered element of the surface or centerline must lie.
- Straightness tolerance controls surface elements only and ensures uniformity of rate of taper on conical surfaces.
- On flat surfaces, straightness tolerance indicates straightness control in one direction only.
Circularity (Roundness) Tolerance
- Circularity refers to a condition where all points on the line or on the circumference of a plane cross-section of the feature are the same distance from a common axis or center point.
- Circularity tolerance measures radially and specifies the width between two circular rings for a particular cross-section within which the circular line or the circumference of the feature in that plane shall lie.
- Circularity tolerance is expressed on RFS basis and cannot be modified on an MMC basis since it controls surface elements only.
- The circularity tolerance must be less than half the size tolerance since it must lie in a space equal to half the size tolerance.
Errors of Circularity
- Errors of circularity (out-of-roundness) of a circular line on the periphery of a cross-section of a circular feature may occur as ovality, lobing, or random irregularities from a true circle.
Assessing Circularity
- In assessing roundness, the circularity error is the minimum radial separation between two concentric circles within which all points on the measured surface shall lie.
- The circularity error can be measured using different approaches, including finding the smallest circumscribed circle and the largest inscribed circle.
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Description
Learn about the application of straightness tolerance in controlling surface elements, including cylindrical and conical surfaces, in engineering design. Understand the measuring principles involved.
