# Shared Flashcard Set

## Details

GD&T Definitions 2009
GD&T definitions based on ANSI/ASME Y14.5-2009 Standards
73
Mechanical Engineering
Not Applicable
03/13/2012

Term
 Angularity
Definition
 That condition of a surface, feature's center plane, or feature's axis at any specified angle from a datum plane or datum axis.
Term
 Boundary, Inner
Definition
 A worst-case boundary generated by the smallest feature (MMC for an internal feature and LMC for an external feature) minus the stated geometric tolerance and any additional geometric tolerance (if applicable) resulting from the feature's departure from its specified material condition.
Term
 Boundary, Least Material (LMB)
Definition
 The limit defined by a tolerance or combination of tolerances that exists on or inside the material of a feature(s).
Term
 Boundary, Maximum Material (MMB)
Definition
 The limit defined by a tolerance or combination of tolerances that exists on or outside the material of a feature(s).
Term
 Boundary, Outer
Definition
 A worst-case boundary generated by the largest feature (LMC for an internal feature and MMC for an external feature) plus the stated geometric tolerance and any additional geometric tolerance (if applicable) resulting from the feature's departure from its specified material condition.
Term
 Circularity (Roundness)
Definition
 (a) For a feature other than a sphere, all points of the surface intersected by any plane perpendicular to an axis or spine (curved line) are equidistant from that axis or spine.   (b) For a sphere, all points of the surface intersected  by any plane passing through a common center are equidistant from that center.
Term
 Coaxiality
Definition
 That condition where the axes of the unrelated actual mating envelope, axis of the unrelated minimum material envelope, or median points, as applicable of one or more surfaces of revolution, are coincident with a datum axis or another feature axis.
Term
 Complex Feature
Definition
 A single surface of compound curvature or a collection of other features that constrains up to six degrees of freedom.
Term
 Concentricity
Definition
 That condition where the median points of all diametrically opposed elements of a surface of revolution (or the median points of correspondingly located elements of two or more radially disposed features) are congruent with a datum axis (or center point).
Term
 Coplanarity
Definition
 That condition of two or more surfaces having all elements in one plane.
Term
 Constraint
Definition
 A limit to one or more degrees of freedom.
Term
 Cylindricity
Definition
 That condition of a surface of revolution in which all points of the surface are equidistant from a common axis.
Term
 Datum
Definition
 A theoretically exact point, axis, line, plane or combination thereof derived from the theoretical datum feature simulator.
Term
 Datum Axis
Definition
 The axis of a datum feature simulator established from the datum feature.
Term
 Datum Center Plane
Definition
 The center plane of a datum feature simulator established from the datum feature.
Term
 Datum Feature
Definition
 A feature that is identified with either a datum feature symbol or a datum target symbol.
Term
 Datum Feature Simulator (Theoretical)
Definition
 The theoretically perfect boundary used to establish a datum from a specified datum feature.
Term
 Datum Feature Simulator (Physical)
Definition
 The physical boundary used to establish a simulated datum from a specified datum feature.
Term
 Datum Reference Frame
Definition
 Three mutually perpendicular intersecting datum planes.
Term
 Datum, Simulated
Definition
 A point, axis, line or plane (or combination thereof) coincident with or derived from processing or inspection equipment, such as the following simulators: a surface plate, a gage surface, a mandrel or mathematical simulation.
Term
 Datum Target
Definition
 The designated points, lines or areas that are used in establishing a datum. Datum targets are used in establishing a datum reference frame.
Term
 Diameter, Average
Definition
 The average of several diametric measurements across a circular or cylindrical feature.
Term
 Dimension
Definition
 A numerical value(s) or mathematical expression in appropriate units of measure used to define the form, size, orientation or location, of a part or feature.
Term
 Dimension, Basic
Definition
 A theoretically exact dimension.
Term
 Dimension, Reference
Definition
 A dimension, usually without a tolerance, that is used for informational purposes only.
Term
 Envelope, Actual Mating
Definition
 A similar perfect feature'(s) counterpart of smallest size that can be contracted about an external feature(s) or largest size that can be expanded within an internal feature(s) so that it coincides with the surface(s) at the highest points. This envelope is outside the material.
Term
 Unrelated Actual Mating Envelope
Definition
 A similar perfect feature(s) counterpart expanded within an internal feature(s) or contracted about an external feature(s), and not constrained to any datum(s).
Term
 Related Actual Mating Envelope
Definition
 A similar perfect feature(s) counterpart expanded within an internal feature(s) or contracted about an external feature(s) while constrained either in orientation or location or both to the applicable datum(s).
Term
 Envelope, Actual Minimum Material
Definition
 A similar perfect feature(s) counterpart of largest size that can be expanded within an external feature(s) or smallest size that can be contracted about an internal feature(s) so that it coincides with the surface(s) at the lowest points. This envelope is within the material.
Term
 Unrelated Actual Minimum Material Envelope
Definition
 A similar perfect feature(s) counterpart contracted about an internal feature(s) or expanded within an external feature(s), and not constrained to any datum reference frame.
Term
 Related Actual Minimum Material Envelope
Definition
 A similar perfect feature(s) counterpart contracted about an internal feature(s) or expanded within an external feature(s) while constrained in either orientation or location or both to the applicable datum(s).
Term
 Feature
Definition
 A physical portion of a part such as a surface, pin, hole, slot or its representation on drawings, models or digital data files.
Term
 Feature Axis
Definition
 The axis of the unrelated actual mating envelope of a feature.
Term
 Feature, Center Plane of
Definition
 The center plane of the unrelated actual mating envelope.
Term
 Derived Median Plane
Definition
 An imperfect (abstract) plane formed by the center points of all line segments bounded by the feature. These line segments are normal (perpendicular) to the center plane of the unrelated actual mating envelope.
Term
 Derived Median Line
Definition
 An imperfect (abstract) line formed by the center points of all cross sections of the feature. These cross sections are normal (perpendicular) to the axis of the unrelated actual mating envelope.
Term
 Regular Feature of Size
Definition
 One cylindrical or spherical surface, a circular element and a set of two opposed parallel elements or opposed parallel surfaces, each of which is associated with a directly toleranced dimension.
Term
 Irregular Feature of Size
Definition
 Two types of irregular features of size are as follows:   (a) a directly toleranced feature or collection of features that may contain or be contained by an actual mating envelope that is a sphere, cylinder or pair of parallel planes.   (b) a directly toleranced feature or collection of features that may contain or be contained by an actual mating envelope other than a sphere, cylinder or pair of parallel planes.
Term
 Feature Control Frame
Definition
 A rectangle divided into compartments containing the geometric characteristic symbol followed by the tolerance value or description, modifiers and any applicable datum feature references.
Term
 Feature-Relating Tolerance Zone Framework (FRTZF)
Definition
 The tolerance zone framework(s) that controls the basic relationship between the features in a pattern with that framework constrained in rotational degrees of freedom relative to any referenced datum features.
Term
 Free State
Definition
 That condition of a part free of applied forces.
Term
 Free-State Variation
Definition
 The distortion of a part after removal of forces applied during manufacture. This distortion is principally due to weight and flexibility of the part and the release of internal stresses resulting from fabrication.
Term
 Flatness
Definition
 That condition of a surface or derived median plane having all elements in one plane.
Term
 Least Material Condition (LMC)
Definition
 That condition in which a feature of size contains the least amount of material within the stated limits of size (e.g., maximum hole diameter, minimum shaft diameter).
Term
 Maximum Material Condition (MMC)
Definition
 That condition in which a feature of size contains the maximum amount of material within the stated limits of size (e.g., minimum hole diameter, maximum shaft diameter).
Term
 Non-Uniform Tolerance Zone
Definition
 A maximum material boundary and a least material boundary, of unique shape, that encompasses the true profile.
Term
 Parallelism
Definition
 That condition of a surface or feature's center plane, equidistant at all points from a datum plane; or a feature's axis, equidistant along its length from one or more datum planes or datum axis.
Term
 Pattern
Definition
 Two or more features or features of size to which a locational geometric tolerance is applied and are grouped by one of the following methods:   (a)  nX (b)  n COAXIAL HOLES (c)  ALL OVER (d), A <--> B (e)  n SURFACES (f)   Simultaneous Requirement(s) (g)  INDICATED
Term
 Pattern-Locating Tolerance Zone Framework(PLTZF)
Definition
 The tolerance zone framework that controls the basic relationship between the features in a pattern with that framework constrained in translational and rotational degrees of freedom relative to the referenced datum features.
Term
 Perpendicularity
Definition
 That condition of a surface, feature's center plane or feature's axis at a right angle to a datum plane or datum axis.
Term
 Plane, Tangent
Definition
 A plane that contacts the high points of the specified feature surface.
Term
 Position
Definition
 The location of one or more features of size relative to one another or to one or more datums. A positional tolerance defines either of the following:   (a) a zone within which the center, axis, or center plane of a feature of size is permitted to vary from a true theoretically exact) position.   (b) (where specified on an MMC or LMC basis) a boundary, defined as the virtual condition, located at the true (theoretically exact) position, that may not be violated by the surface or surfaces of the considered feature of size.
Term
 Profile
Definition
 An outline of a surface, a shape made up of one or more features or a two-dimensional element of one or more features.
Term
 Regardless of Feature Size (RFS)
Definition
 Indicates a geometric tolerance applies at any increment of size of the actual mating envelope of the feature of size.
Term
 Regardless of Material Boundary (RMB)
Definition
 Indicates that a datum feature simulator progresses from MMB toward LMB until it makes maximum contact with the extremities of a feature(s).
Term
 Restraint
Definition
 The application of force(s) to a part to simulate its assembly or functional condition resulting in possible distortion of a part from its free-state condition.
Term
 Resultant Condition
Definition
 The single worst-case boundary generated by the collective effects of a feature of the size's specified MMC or LMC, the geometric tolerance for that material condition, the size tolerance and the additional geometric tolerance derived from the feature's departure from its specified material condition.
Term
 Runout
Definition
 A tolerance used to control the functional relationship of one or more features to a datum axis established from a datum feature specified at RMB.
Term
 Simultaneous Requirement
Definition
 Where two or more geometric tolerances apply as a single pattern or part requirement.
Term
 Size, Actual Local
Definition
 The measured value of any individual distance at any cross section of a feature of size.
Term
 Size, Limits of
Definition
 The extent within which variations of geometric form, as well as size, are allowed.
Term
 Size, Nominal
Definition
 The designation used for purposes of general identification.
Term
 Straightness
Definition
 That condition where an element of a surface or derived median line is a straight line. A straightness tolerance specifies a tolerance zone within which the considered element of a surface or derived median line must lie.
Term
 Statistical Tolerancing
Definition
 The assignment of tolerances to related components of an assembly on the basis of sound statistics (such as the assembly tolerance is equal to the square root of the sum of the squares of the individual tolerances).
Term
 Symmetry
Definition
 That condition where the median points of all opposed or correspondingly located elements of two or more feature surfaces are congruent with a datum axis or center plane.
Term
 Tolerance
Definition
 The total amount a specific dimension is permitted to vary. The tolerance is the difference between the maximum and minimum limits.
Term
 Tolerance, Bilateral
Definition
 A tolerance in which variation is permitted in both directions from the specified dimension.
Term
 Tolerance, Geometric
Definition
 The general term applied to the category of tolerances used to control size, form, profile, orientation, location and runout.
Term
 Tolerance, Unilateral
Definition
 A tolerance in which variation is permitted in one direction from the specified dimension.
Term
 True Position
Definition
 The theoretically exact location of a feature.
Term
 True Profile
Definition
 A profile defined by basic radii, basic angular dimensions, basic coordinate dimensions, basic size dimensions, undimensioned drawings, formulas or mathematical data, including design models.
Term
 Uniform Tolerance Zone
Definition
 The distance between two boundaries equally or unequally disposed about the true profile or entirely disposed on one side of the true profile.
Term
 Virtual Condition
Definition
 A constant boundary generated by the collective effects of a considered feature of the size's specified MMC or LMC and the geometric tolerance for that material condition.
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