Term
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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. |
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Term
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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. |
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Term
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Definition
| A theoretically exact point, axis, line, plane, or combination thereof derived from the theoretical datum feature simulator. A datum is the origin from which the location or geometric characteristics of features of a part are established. |
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Term
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Definition
| A feature that is identified with either a datum feature symbol or a datum target symbol. |
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Term
| True Geometric Counterpart |
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Definition
| The theoretically perfect boundry (virtual condition or actual mating envelope) or best-fit (tangent) plane of a specified datum feature. |
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Term
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Definition
| Encompasses two types: theoretical and physical. |
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Term
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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. |
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Term
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Definition
| Are the designated points, lines, or areas that are used in establishing a datum. |
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Term
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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. |
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Term
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Definition
A theoretically exact dimension.
NOTE: A basic dimension is indicated by one of the methods shown in Figs. 3-10 and 7-1. |
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Term
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Definition
| A dimension, usually without a tolerance, that is used for informational purposes only. |
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Term
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Definition
| A physical portion of a part such as a surface, pin, hole, or slot or its representation on drawings, models, or digital data files. |
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Term
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Definition
| the axis of the unrelated actual mating envelope of a feature. NOTE: In this Standard, when the term “feature axis” is used, it refers to the axis of the unrelated actual mating envelope unless specified otherwise. |
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Term
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Definition
| the center plane of the unrelated actual mating envelope of a feature. NOTE: In this Standard, when the term “feature center plane” is used, it refers to the center plane of the unrelated actual mating envelope unless specified otherwise. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| encompasses two types: regular and irregular. |
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Term
| Maximum Material Contition (MMC) |
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Definition
| The 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). |
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Term
| Least Material Contition (LMC) |
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Definition
| The 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). |
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Term
| Regardless of Feature Size (RFS) |
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Definition
| Indicates a geometric tolerance applies at any increment of size of the actual mating envelope of the feature of size. |
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Term
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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. See Figs. 2-12, 2-13, 2-15, and 2-16. |
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Term
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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.
See Figs. 2-12, 2-13, 2-15, and 2-16. |
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Term
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Definition
| The measured value of any individual distance at any cross section of a feature of size. See Fig. 1-1. |
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Term
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Definition
| This envelope is outside the material. 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. Two types of actual mating envelopes — unrelated and related |
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Term
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Definition
| The specified maximum and minimum sizes. |
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Term
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Definition
| The designation used for purposes of general identification. |
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Term
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Definition
| The actual value of a resultant contition boundry. |
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Term
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Definition
| The dimensional value of a virtual contition boundry. |
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Term
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Definition
| A plane that contacts the high points of the specified feature surface. |
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Term
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Definition
| The total amount a specific dimension is permitted to vary. The tolerance is the difference between the maximum and minimum limits. |
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Term
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Definition
| A tolerance in which variation is permitted in both directions from the specified dimension. |
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Term
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Definition
| The general term applied to the category of tolerances used to control size, form, profile, orientation, location, and runout. |
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Term
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Definition
| The theoretically exact location of a feature of size, as established by basic dimensions. |
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Term
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Definition
| A tolerance in which variation is permitted in one direction from the specified dimension. |
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Term
| Full Indicator Movement (FIM) |
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Definition
| The total movement of an indicator for each considered feature must be within its runout tolerance. |
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Term
| Feature-Relating Tolerance Zone Framework (FRTZF) |
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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. |
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Term
| Pattern-Locating Tolerance Zone Framework (PLTZF) |
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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. |
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Term
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Definition
| Is the condition of a surface, feature’s center plane, or feature’s axis at any specified angle from a datum plane or datum axis. |
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Term
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Definition
| Is the 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. |
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Term
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Definition
| Is the condition of a surface, feature’s center plane, or feature’s axis at a right angle to a datum plane or datum axis. |
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Term
| Least Material Boundary (LMB) |
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Definition
| The limit defined by a tolerance or combination of tolerances that exists on or inside the material of a feature(s). |
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Term
| Maximum Material Boundary (MMB) |
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Definition
| The limit defined by a tolerance or combination of tolerances that exists on or outside the material of a feature(s). |
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Term
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Definition
Is a condition where an element of a surface,
or derived median line, is a straight line. |
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Term
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Definition
| Iis a condition of a surface where (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. |
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Term
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Definition
| is 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. |
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Term
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Definition
| A single surface of compound curvature or a collection of other features that constrains up to six degrees of freedom. |
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Term
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Definition
| Is 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). |
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Term
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Definition
| Is the condition of two or more surfaces having all elements in one plane. |
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Term
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Definition
| A limit to one or more degrees of freedom. |
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Term
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Definition
| Is a condition of a surface of revolution in which all points of the surface are equidistant from a common axis. |
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Term
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Definition
The axis of a datum feature simulator established
from the datum feature. |
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Term
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Definition
| The center plane of a datum feature simulator established from the datum feature. |
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Term
| Datum Feature Simulator (Theoretical) |
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Definition
| The theoretically perfect boundary used to establish a datum from a specified datum feature. |
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Term
| Datum Feature Simulator (Physical) |
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Definition
the physical boundary used to establish a simulated datum from a specified datum feature.
NOTE: For example, a gage, fixture element, or digital data (such as machine tables, surface plates, a mandrel, or mathematical simulation) —although not true planes — are of sufficient quality that the planes derived from them are used to establish simulated datums. Physical datum feature simulators are used as the physical embodiment of the theoretical datum feature simulators during manufacturing and inspection. |
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Term
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Definition
| Is three mutually perpendicular intersecting datum planes. NOTE: Whenever the term “datum feature simulator” is used in this Standard, it refers to the theoretical, unless specifically otherwise indicated. |
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Term
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Definition
| Is the average of several diametric measurements across a circular or cylindrical feature. Normally, enough (at least four) measurements are taken to ensure the establishment of an average diameter. |
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Term
| Unrelated Actual Mating Envelope |
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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). See Fig. 1-1. |
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Term
| Related Actual Mating Envelope |
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Definition
| A similar perfect feature 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). See Fig. 1-1. |
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Term
| Actual Minimum Material Envelope |
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Definition
| This envelope is within the material. 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. Two types of actual minimum material envelopes — unrelated and related |
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Term
| Unrelated Actual Minimum Material Envelope |
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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. |
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Term
| Related Actual Minimum Material Envelope |
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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). |
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Term
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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. |
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Term
| Irregular Feature of Size |
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Definition
The 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 |
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Term
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Definition
| Is a rectangle divided into compartments containing the geometric characteristic symbol followed by the tolerance value or description, modifiers, and any applicable datum feature references. |
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Term
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Definition
| The condition of a part free of applied forces. |
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Term
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Definition
| is 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. |
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Term
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Definition
| Is the condition of a surface or derived median plane having all elements in one plane. |
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Term
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Definition
| A non-uniform tolerance zone is a maximum material boundary and a least material boundary, of unique shape, that encompasses the true profile. These boundaries are defined in a CAD file or by basic dimensions A non-uniform tolerance zone is a maximum material boundary and a least material boundary, of unique shape, that encompasses the true profile. These boundaries are defined in a CAD file or by basic dimensions See Figs. 8-9, 8-10, and 8-11. |
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Term
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Definition
| Is the location of one or more features of size relative to one another or to one or more datums. |
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Term
| Regardless of Material Boundary (RMB) |
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Definition
| indicates that a datum feature simulator progresses from MMB toward LMB until it makes maximum contact with the extremities of a feature(s). |
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Term
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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. See para. 4.20. |
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Term
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Definition
| Is 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. NOTE: The figures in this Section use measurement techniques to explain the tolerance zones. It is neither the intent nor within the scope of this Standard to define measurement methods. |
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Term
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Definition
| Is where two or more geometric tolerances apply as a single pattern or part requirement. A simultaneous requirement applies to position and profile tolerances that are located by basic dimensions, related to common datum features referenced in the same order of precedence at the same boundary conditions. In a simultaneous requirement there is no translation or rotation between the datum reference frames of the included geometric tolerances, thus creating a single pattern. Figures 4-39 and 4-40 show examples of simultaneous requirements. |
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Term
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Definition
| Is the assigning 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). |
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Term
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Definition
| Is 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. |
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Term
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Definition
| Is a profile defined by basic radii, basic angular dimensions, basic coordinate dimensions, basic size dimensions, undimensioned drawings, formulas, or mathematical data, including design models. |
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Term
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Definition
| Is the location of one or more features of size relative to one another or to one or more datums. |
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Term
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Definition
| Is the distance between two boundaries equally or unequally disposed about the true profile or entirely disposed on one side of the true profile. |
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