ASME Y14.5-2009 Dimensioning and Tolerancing Flashcards

A set of flashcards covering definitions and rules from Section 1 of the ASME Y14.5-2009 standard.

ASME Y14.5-2009

The Standard that establishes uniform practices for stating and interpreting dimensioning, tolerancing, and related requirements for use on engineering drawings and in related documents.

Boundary, Inner

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 resulting from the feature's departure from its specified material condition.

Boundary, Least Material (LMB)

The limit defined by a tolerance or combination of tolerances that exists on or inside the material of a feature(s).

Boundary, Maximum Material (MMB)

The limit defined by a tolerance or combination of tolerances that exists on or outside the material of a feature(s).

Boundary, Outer

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 resulting from the feature's departure from its specified material condition.

Complex Feature

A single surface of compound curvature or a collection of other features that constrains up to six degrees of freedom.

Constraint

A limit to one or more degrees of freedom.

Datum

A theoretically exact point, axis, line, plane, or combination thereof derived from the theoretical datum feature simulator.

Datum Axis

The axis of a datum feature simulator established from the datum feature.

Datum Center Plane

The center plane of a datum feature simulator established from the datum feature.

Datum Feature

A feature that is identified with either a datum feature symbol or a datum target symbol.

Datum Feature Simulator (Theoretical)

The theoretically perfect boundary used to establish a datum from a specified datum feature.

Datum Feature Simulator (Physical)

The physical boundary used to establish a simulated datum from a specified datum feature, such as a gage, fixture element, or digital data.

Datum, Simulated

A point, axis, line, or plane (or combination thereof) coincident with or derived from processing or inspection equipment, such as a surface plate, gage surface, or mandrel.

Dimension

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.

Dimension, Basic

A theoretically exact dimension.

Dimension, Reference

A dimension, usually without a tolerance, that is used for informational purposes only; it is a repeat of a dimension or is derived from other values shown on the drawing.

Envelope, Actual Mating

This envelope is outside the material; it is 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.

Unrelated Actual Mating Envelope

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).

Related Actual Mating Envelope

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).

Envelope, Actual Minimum Material

This envelope is within the material; it is 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.

Feature

A physical portion of a part such as a surface, pin, hole, or slot or its representation on drawings, models, or digital data files.

Feature Axis

The axis of the unrelated actual mating envelope of a feature.

Feature, Center Plane of

The center plane of the unrelated actual mating envelope of a feature.

Derived Median Plane

An imperfect (abstract) plane formed by the center points of all line segments bounded by the feature, where line segments are normal to the center plane of the unrelated actual mating envelope.

Derived Median Line

An imperfect (abstract) line formed by the center points of all cross sections of the feature, where cross sections are normal to the axis of the unrelated actual mating envelope.

Regular Feature of Size

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.

Irregular Feature of Size

A directly toleranced feature or collection of features that may contain or be contained by an actual mating envelope that is a sphere, cylinder, pair of parallel planes, or other shape.

Feature-Relating Tolerance Zone Framework (FRTZF)

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.

Free State

The condition of a part free of applied forces.

Least Material Condition (LMC)

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).

Maximum Material Condition (MMC)

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).

Pattern

Two or more features or features of size to which a locational geometric tolerance is applied and are grouped by specific methods like $nX$, simultaneous requirements, or INDICATED.

Pattern-Locating Tolerance Zone Framework (PLTZF)

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.

Plane, Tangent

A plane that contacts the high points of the specified feature surface.

Regardless of Feature Size (RFS)

Indicates a geometric tolerance applies at any increment of size of the actual mating envelope of the feature of size.

Regardless of Material Boundary (RMB)

Indicates that a datum feature simulator progresses from $MMB$ toward $LMB$ until it makes maximum contact with the extremities of a feature(s).

Restraint

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.

Resultant Condition

The single worst-case boundary generated by the collective effects of a feature of size's specified $MMC$ or $LMC$, the geometric tolerance, the size tolerance, and any additional geometric tolerance.

Size, Actual Local

The measured value of any individual distance at any cross section of a feature of size.

Size, Limits of

The specified maximum and minimum sizes.

Size, Nominal

The designation used for purposes of general identification.

Tolerance

The total amount a specific dimension is permitted to vary; the difference between the maximum and minimum limits.

Tolerance, Bilateral

A tolerance in which variation is permitted in both directions from the specified dimension.

Tolerance, Geometric

The general term applied to the category of tolerances used to control size, form, profile, orientation, location, and runout.

Tolerance, Unilateral

A tolerance in which variation is permitted in one direction from the specified dimension.

True Position

The theoretically exact location of a feature of size, as established by basic dimensions.

Virtual Condition

A constant boundary generated by the collective effects of a considered feature of size's specified $MMC$ or $LMC$ and the geometric tolerance for that material condition.

Dimension Line

A line which, with its arrowheads, shows the direction and extent of a dimension.

Extension Line

A line used to indicate the extension of a surface or point to a location preferably outside the part outline.

Leader

A line used to direct a dimension, note, or symbol to the intended place on the drawing, normally terminating in an arrowhead or a dot.

Millimeter Dimensioning Rule

Where the dimension is less than one millimeter, a zero precedes the decimal point (e.g., $0.745$).

Decimal Inch Dimensioning Rule

A zero is not used before the decimal point for values less than $1\,\text{in}$ (e.g., $.75$).

Rectangular Coordinate Dimensioning

A method where linear dimensions specify distances in coordinate directions from two or three mutually perpendicular planes.

Tabular Dimensioning

A type of rectangular coordinate dimensioning in which dimensions from mutually perpendicular planes are listed in a table on the drawing.

Polar Coordinate Dimensioning

A method where a linear and an angular dimension specify a distance from a fixed point at an angular direction from two or three mutually perpendicular planes.