Top ETI Banner


ISO Geometrical Tolerancing Glossary

iso logoAs the globalization of manufacturing continues, the ISO standards will play a more significant role in the U.S.  If your company is interested in global sourcing and learning how to read drawings created in other countries, ETI's ISO Geometrical Tolerancing workshop is vital to your success.

Learn the ins and outs of utilizing the ISO standards and gain a fundamental knowledge of ISO 1101:2004, related standards, and their application on drawings. Read more about our workshop.

The course includes Alex Krulikowski's ISO Geometrical Tolerancing Reference Guide, a unique reference guide that will help you to learn about dimensioning and tolerancing and provide a handy reference for you on the job. The terms listed below are from the glossary section of the reference guide.


The following terms are related to ISO geometrical tolerancing. The definitions are from ISO 1101:2004 and its companion published standards.

DO YOU UNDERSTAND ISO GEOMETRICAL TOLERANCING?

ETI offers several options to help you understand ISO geometrical tolerancing:

Actual Size — The size of a feature, obtained by measurement (ISO 286-1:1998)

Actual Local Size — Any individual distance at any cross section of a feature, i.e. any size measured between any opposed points (ISO 2692:2006)

Angular Dimension — The angle between two features or the angle of an angular feature of size (ISO 129-1:2004)
angularity Angularity Tolerance — A geometrical tolerance that defines the allowable deviation from the exact (TED) angle

Appearance Imperfections — Scattered imperfections in the outermost surface layer, often without sharp contours and often without practicably measurable depth or height (ISO 8785:1998)

Associated Derived Feature — A center point, axis, or median plane of perfect form derived from one or more associated integral features (ISO 8015:1985)

Associated Integral Feature — An integral feature of perfect form associated with the extracted integral feature in accordance with conventions described in the ISO standards (ISO 8015:1985)

Auxiliary Dimension — A dimension given for information purposes only. It does not govern production or inspection operations and it is derived from other values shown on the drawing or in related documents. An auxiliary dimension is given in parentheses and no tolerance applies to it. (ISO 129:1985)

Basic Dimension (or Dimensional Value) — The numerical value of a dimension expressed in a specific unit and indicated on drawings with lines and relevant symbols (ISO 129-1:2004)

Basic Hole — Where the hole is used for the basis for a hole-basis system of fits; the letter used for the hole-basis system is "H"; in a hole-basis system, the lower deviation is zero (ISO 286-1:1988)

Basic Size, Nominal Size — The size from which the upper limits of a size are derived by the application of the upper and lower deviations (ISO 286-1:1988)

Basic Shaft — Where the shaft is used for the shaft-basis system of fits; the letter used for a shaft basis system is "h" (ISO 286-1:1988)

Burr — A rough remainder of material outside the ideal geometrical shape of an external edge, residue of machining or a forming process (ISO 13715:2000)


ISO GEOMETRICAL TOLERANCING GUIDE

Based on ISO 1101:2004 and companion standards

isoguideAlex and his team of dimensional engineering mentors spent nearly a year compiling information about the ISO GPS standards. Alex Krulikowski's ISO Geometrical Tolerancing Reference Guide allows the reader to quickly and easily look up information on a topic without having to navigate through numerous ISO standards.

Carry it with you on the job and have a resource to all your ISO geometrical tolerancing questions at your fingertips. Read more about it.

order now

Click the graphic to look inside the book.

Clearance — The positive difference between the sizes of the hole and the shaft, when the hole is larger than the shaft (ISO 286-1:1988)

Clearance Fit — A fit that always provides a positive difference between holes and shaft when assembled (ISO 286-1:1988)

Coaxial Diameters — Two (or more) diameters that are shown on the drawing as being on the same center line (axis)
concentricity Coaxiality Tolerance — A geometrical tolerance that defines a requirement for the permissible location deviation of a median line from a datum axis

Collective Requirement — An MMVC or LMVC boundary that the toleranced feature(s) of size cannot violate. (ISO 2692:2006)

Combination of Recessing and Raising — Partially recessed and partially raised imperfections (ISO 8785:1998)
concentricity Concentricity Tolerance — A geometrical tolerance that defines a requirement for the permissible location deviation of a center point from a datum center point

Coordinate Dimensioning — A method of dimensioning from a reference feature in a coordinate system (ISO 129-1:2004)

Coplanar Surfaces — Two or more surfaces that are nominally in the same plane
cylindricity Cylindricity Tolerance — A geometrical tolerance that establishes a requirement for the cylindricity deviation of a surface of a cylinder

Datum — A theoretical exact geometric reference (such as axes, planes, straight lines, etc.) used to establish the location of a datum (ISO 5459:1981)
datum feature Datum Feature — A real feature of a part (such as an edge, a surface, or a hole, etc.) that is used to establish the location of a datum (ISO 5459:1981)

Datum Feature Displacement — The allowable movement, or looseness between the part datum feature and the simulated datum feature (ISO 2692:2006)

Datum-System — A group of two or more separate datums used as a combined reference for a toleranced feature (ISO 5459:1981)
datum target Datum Target — A point, line or limited area on the workpiece to be used for contact with the manufacturing and inspection equipment, to define the required datums in order to satisfy the functional requirements (ISO 5459:1981)

Deviation — The algebraic difference between a size and the corresponding basic size (Note: symbols for shaft deviations are lower case letters, and symbols for hole deviations are upper case letters) (ISO 286-1:1988)

Dimension — The distance between two features or the size of a feature of size (ISO 129-1:2004)

Dimension Line — A straight or curved line that indicates a dimension graphically on a drawing (ISO 129-1:2004)

Derived Feature — Center point, median line, or median surface derived from one or more integral features (ISO 14660-1:1996)

Edge — The intersection of two surfaces; an edge can be external or internal
(ISO 13715:2000)

Envelope Requirement — For a feature of size, the envelope of perfect form at maximum material condition may not be violated (ISO 8015:1985)

Evaluation Length — The length in the x-axis used for assessing the profile under evaluation. Where shorter than the entire feature, the evaluation length is the sum of the sampling lengths (ISO 4287:1997)

Extension Line — A line connecting the feature(s) to the ends of the corresponding dimension line (ISO 129-1:2004)

Extracted Derived Feature — A center point, median line, or median plane derived from one or more extracted integral features (ISO 14660-1:1999)

Extracted Integral Feature — An approximation of a real feature obtained by extracting a finite number of points from a real feature in accordance with defined conventions (ISO 14660-1:1999)


Click on any link below to learn more about our products
Software Video
Training
Web-Based
Training
Digital Instructor Kits Reference
Books & Materials
Textbooks Workbooks Reference
Charts
Miscellaneous
Products
Free Resources


Extreme Boundary — A general term referring to a theoretical worst-case boundary. An extreme boundary may be an envelope boundary, a virtual condition, or a calculated boundary.

Feature of Size — A geometrical shape defined by a linear or angular dimension that is a size. Typically, a feature of size is a cylinder, a sphere, two opposite parallel surfaces, a cone or wedge. (ISO 14660-1:1999)

Form — The profile of the surface under consideration ignoring variations due to roughness and waviness (see author's comment on page 304)

flatness Flatness Tolerance — A geometrical tolerance that establishes a requirement for the maximum distance between high and low points of a surface

Free State Condition — Condition of a part subjected only to the forces of gravity (ISO 10579:1993)

Fundamental Deviation — Deviation that defines the position of the tolerance zone in relation to the zero line (ISO 286-1:1988)

General Tolerance — A tolerance that often applies in multiple places on a drawing without every application being indicated (ISO 2768-1:1989)

Hole — An internal feature of a workpiece (ISO 286-1:1988)

Hole-Basis System of Fits — A system of fits in which the required clearances or interferences are obtained by associating shafts of various tolerance classes with holes of a single tolerance class (ISO 286-1:1988)

Independency Principle — States that each specified dimensional or geometrical requirement on a drawing shall be met independently, unless a particular relationship is specified that invokes an envelope requirement (i.e. MMR, LMR, or envelope requirement) (ISO 8015:1985)

Integral Feature — Surface or line on a surface (ISO 14660-1:1996)

Interference — The negative difference between the sizes of the hole and shaft when the hole is smaller than the shaft (ISO 286-1:1988)

Interference Fit — A fit that always provides a negative difference (interference) between the shaft and the hole when assembled (ISO 286-1:1988)

International Tolerance Grades (IT) — A group of tolerances that vary based on the basic size, but provide the same relative level of accuracy within a given grade (Note: an IT grade is designated with a number; for example, the number 7 in 40H7 or IT7) (ISO 286-1:1988)

Lay — The direction of the predominant surface pattern of a workpiece (see author's comment on page 304)

Leader Line — A line connecting information or requirements, or a reference line with a feature or a dimension line

least material condition Least Material Condition (LMC) — The state of the considered feature in which the feature is everywhere at that limit of size where the material of the feature is at its minimum, e.g. maximum hole diameter and minimum shaft diameter (ISO 2692:2006)
least material condition Least Material Requirement (LMR) — A requirement for a feature of size, defining a geometrical feature of the same type and of perfect form, with a given value for the intrinsic characteristic (dimension) equal to LMVS, which limits the non-ideal feature on the inside of the material (ISO 2692:2006)
DO YOU NEED GD&T TRAINING? TEST YOUR SKILLS TODAY

stacks survey
Do you know how to use stacks to determine part distances or assembly conditions? Do you understand design analysis using geometric tolerances in stacks?

Take our Stacks Skills Survey today.

skills survey
How well do you know GD&T? Do you know the symbols, requirements, tolerance zones, and limitations?

Take the GD&T Skills Survey today.

Least Material Size (LMS) — A dimension defining the least material condition of a feature (ISO 2692:2006)

Least Material Virtual Condition (LMVC) — state of associated feature of least material virtual size (LMVS). For features in the inspection domain, LMVC identifies a condition equivalent to LMVS. (ISO 2692:2006)

Least Material Virtual Size (LMVS) — The size generated by the collective effect of the least material size of a feature of size and the geometrical tolerance given for the derived feature of the same feature of size (ISO 2692:2006)

Limits of Size — The extreme permissible sizes of a feature

Linear Dimension — The linear distance between two features or the linear size of a feature of size (ISO 129-1:2004)

Linear Tolerance (size dimension) — Controls only the actual local sizes (two point measurements) of a feature of size, not its form deviations; a result of the independency principle (ISO 8015:1985)

Max-Rule — A surface texture requirement that is considered acceptable only if none of the measured values of the parameter over the entire surface being evaluated exceed the value specified on the drawing (ISO 4288:1996)
maximum material condition Maximum Material Condition (MMC) — The state of the considered feature in which the feature is everywhere at that limit of size where the material of the feature is at its maximum, e.g. minimum hole diameter and maximum shaft diameter (ISO 2692:2006)
maximum material condition Maximum Material Requirement (MMR) — A requirement for a feature of size, defining a geometrical feature of the same type and of perfect form, with a given value for the intrinsic characteristic (dimension) equal to MMVS, which limits the non-ideal feature on the outside of the material (ISO 2692:2006)

Maximum Material Size (MMS) — A dimension defining the maximum material condition of a feature of size (ISO 2692:2006)

Maximum Material Virtual Condition (MMVC) — The state of associated feature of maximum material virtual size (MMVS) (ISO 2692:2006)

Maximum Material Virtual Size (MMVS) — The size generated by the collective effects of the maximum material size of a feature of size and the geometrical tolerance given for the derived feature of the same feature of size
(ISO 2692:2006)

Nominal Derived Feature — A center point, axis, or median plane (of perfect form) derived from one or more nominal integral features (ISO 14660-1:1999)

Nominal Integral Feature — A theoretically exact feature as defined by a technical drawing or other means (i.e. solid model) (ISO 14660-1:1999)

Non Rigid Part — A part which deforms to an extent that in the free state is beyond the dimensional and/or geometrical tolerances on the drawing
(ISO 10579:1993)
parallelism Parallelism Tolerance — A geometrical tolerance that defines the allowable deviation from parallel

Passing — A deviation outside the ideal geometrical shape of an internal edge
(ISO 13715:2000)

Click on any link below to learn more about our products
Software Video
Training
Web-Based
Training
Digital Instructor Kits Reference
Books & Materials
Textbooks Workbooks Reference
Charts
Miscellaneous
Products
Free Resources
perpendicularity Perpendicularity Tolerance — A geometrical tolerance that defines the allowable deviation from a right angle

Position Tolerance — Defines the allowable deviation from the theoretically exact dimensions. A position tolerance can also be used to define permissible deviation for orientation and form.
profile any line Profile Any Line — A geometrical tolerance that defines a requirement for the permissible location, orientation and form deviation of a line element of a profile defined with a TED. A profile any line tolerance is used on line elements that are not nominally straight. A profile any line tolerance frame should be applied to the integral feature or its extension line with a directed leader (ISO 1101:2004)
profile any surface Profile Any Surface — A geometrical tolerance that defines a requirement for the permissible size, location, orientation and form deviation of a workpiece profile defined with a TED. A profile tolerance is used on surfaces that are not nominally flat (ISO 5458:1998)

Raising — Outwardly directed surface imperfection

Real Surface — The surface limiting the body and separating it from the surrounding medium (ISO 4287:1997)

Real Surface of a Workpiece — Set of features which physically exist and separate the entire workpiece from the surrounding medium (ISO 14660-1:1996)

Recession — Inwardly directed surface imperfection (ISO 8785:1998)

Reference Surface — The parameters of surface imperfections are assessed from the surface area adjacent to the imperfection (ISO 8785:1998)

Regardless of Feature Size — Defines a condition where geometrical tolerances apply independently to the actual local size of individual features. The geometrical deviation for a given feature may be at its maximum limit even though the feature of size is not at the maximum material size or least material size. Also, when using RFS, a virtual condition does not exist. (ISO 8015:1985)

Recession — Inwardly directed surface imperfection

Roughness — Surface irregularities that result from various machining processes. The action of the cutting tool, chemical action, polishing, lapping and the structure of the material all contribute to the roughness of a surface (see author's comment on page 304)

Roughness Height — The height of the irregularities with respect to a reference line, often measured in micrometers (see author's comment on page 304)

Roughness Width — The distance parallel to the nominal surface between successive peaks or ridges that constitute the predominate pattern of the roughness, usually measured in millimeters (see author's comment on page 304)
roundness Roundness Tolerance — A geometrical tolerance that establishes a requirement for the roundness error of each circular element of a surface or revolution. Unless otherwise specified, a roundness tolerance applies to each (all) circular elements of the integral feature.

Sampling Length — (lp, lr, lw) is the length in the direction of the x axis used for identifying the irregularities that characterize the profile under evaluation.
(ISO 4287:1997)

Shaft — An external feature of a workpiece (cylindrical or planar) (ISO 286-1:1988)

Shaft-Basis System of Fits — A system of fits in which the required clearances or interferences are obtained by associating holes of various tolerance classes with shafts of a single tolerance class (ISO 286-1:1988)

Sharp Edge — An edge that does not have more than a ± 0.05 deviation from the ideal geometrical shape (ISO 13715:2000)

Simulated Datum Feature — A real surface of adequately precise form (such as a surface plate, a bearing, or a mandrel, etc.) contacting the datum feature(s) and used to establish the datums (ISO 5459:1981)

16%-Rule — A surface texture requirement that is considered acceptable if not more than 16% of all measured values—based on the evaluation length—exceed the value specified on the drawing (ISO 4288:1996)

Size — A number expressing, in a particular unit, the numerical value of a linear dimension (ISO 286-1:1988)

Size Tolerance — The difference between the maximum and minimum limits of size (Note: size tolerance is an absolute value without sign) (ISO 286-1:1988)

Straightness Tolerance — A geometrical tolerance that defines the amount of allowable deviation of a real line element or real median line

Surface Texture — The local deviations of a surface from its ideal shape (e.g. perfect flat, perfect cylindrical, etc. (see author's comment on page 304)

Surface Profile — The result from the intersection of the real surface of a workpiece by a specified plane (see author's comment on page 304)
symmetry Symmetry Tolerance — A geometrical tolerance that defines a requirement for the permissible location deviation of a median surface from a datum median plane

Technical Drawing — Technical information, given in an information carrier, graphically presented in accordance with agreed rules and usually to scale (ISO 10209-1:1992)
theoretically exact dimension Theoretically Exact Dimensions (TED) — Dimensions enclosed in a frame are the theoretically exact location, orientation, or profile of a feature or group of features (ISO 1101:2004)

Tolerance Class — The term used for a combination of fundamental deviation and tolerance grade (e.g. h9, D13, etc.) (ISO 286-1:1988)
tolerance frame Tolerance Frame — A rectangular frame divided into two or more compartments that contain three types of information: a geometrical characteristic symbol, a tolerance value with modifiers, and datum indications, if needed
(ISO 1101:2004)

Tolerance Zone — The zone contained between two lines representing the maximum and minimum limits of size, defined by the magnitude of the tolerance and its position relative to the zero line (ISO 286-1:1988)

Transmission Band — Cut-off values for short wave and long wave filters for measuring a roughness profile parameter (see author's comment on page 304)

Transition Fit — A fit that may provide either a clearance or interference between a hole and shaft when assembled, depending upon the actual sizes of the hole and shaft (ISO 286-1:1988)

True Profile — A profile defined by theoretically exact dimensions (ISO 1660:1987)
Undercut — A deviation inside the ideal geometrical shape of an internal or external edge (ISO 13715:2000)

Waviness — The irregularities that are outside the roughness width cut off values (evaluation lengths); the widely spaced repetitive deviations of the surface texture (see author's comment on page 304)

Waviness Height — The peak to valley distance of the surface profile, measured in millimeters (see author's comment on page 304)

Zero Line — A straight line, representing the basic size, from which deviations and tolerances are referred (ISO 286-1:1988)
 
ISO GEOMETRICAL TOLERANCING GUIDE

Based on ISO 1101:2004 and companion standards

isoguideAlex and his team of dimensional engineering mentors spent nearly a year compiling information about the ISO GPS standards. Alex Krulikowski's ISO Geometrical Tolerancing Reference Guide allows the reader to quickly and easily look up information on a topic without having to navigate through numerous ISO standards.

Carry it with you on the job and have a resource to all your ISO geometrical tolerancing questions at your fingertips. Read more about it.

order now

Click the graphic to look inside the book.

 

 



Home | News | Solutions | Alex Krulikowski | History | Testimonials | ETImail | Why Choose ETI?
Products | Blog | Downloads | On-Site Training | Public Seminars | Live Web Training | Engineering Services
Tech Papers | Online Training | Tip of the Month | GD&T Certification | What is GD&T? | GD&T Glossary
HTML Catalog | Catalog | ISO GD&T Glossary | GD&T Savings Calculator | Links | Maps | Media Page | Contact ETI
Reprint Policy

Copyright © 1997 - 2017 Effective Training Inc. an SAE INTERNATIONAL Company All rights reserved.
This file last modified 03/08/11