geometrical dimensioning & tolerancing

Geometrical Dimensioning & Tolerancing ISO 1101 By Hassan Habib

What are we going to learn What is Geometrical Dimensioning & Tolerancing Its : benefits Types Some general principles Details of tolerances of: Form Orientation Location Profile

What is Geometrical Dimensioning Tolerancing

Hmmmm. . . . What would I prefer?

Slide Title Benefits of GD&T

Geometrical tolerances vs size tolerances

Precision & Accuracy

Reduced rework cost

Reduced Defects

Increased understanding Mfg Design Quality

Slide Title Types of GD&T

Types of Geometrical tolerances Form Tolerances Orientation Tolerances Location tolerances runout tolerances Straightness Flatness Circularity Cylindricity Parallelism Perpendicularity Angularity Position Symmetry Concentricity Coaxiality Circular runout Total runout

Slide Title Some general principles

Some general priciples Basic concepts Geometrical tolerances shall be specified in accordance with functional requirements. Manufacturing and inspection requirements can also influence geometrical tolerancing

Some general priciples Basic concepts Geometrical tolerances which are assigned to features related to a datum do not limit the form deviations of the datum feature itself. It may be necessary to specify tolerances of form for the datum feature(s)

Some general priciples Basic concepts Feature control frame

Some general priciples Three golden rules 1. Location tolerances of a feature control location deviation, orientation deviation and form deviation of this feature, and not vice-versa. 2. Orientation tolerances of a feature control orientation and form deviations of this feature and not vice-versa. 3. Form tolerances of a feature control only form deviations of this feature.re control frame

Slide Title Details of Tolerances

Form Tolerances

straightness The tolerance zone, in the considered plane, is limited by two parallel straight lines a distance apart and in the specified direction only Straightness tolerance

straightness Any extracted (actual) generating line on the cylindrical surface shall be contained between two parallel planes T distance apart Straightness tolerance

straightness The extracted (actual) median line of the cylinder to which the tolerance applies shall be contained within a cylindrical zone of diameter Straightness tolerance

fLATNESS The extracted (actual) surface shall be contained between two parallel planes DISTANCE T apart. flatness tolerance

roundness The tolerance zone, in the considered cross-section, is limited by two concentric circles with a difference in radii of t roundness tolerance

CYLINDRICITY The tolerance zone is limited by two coaxial cylinders with a difference in radii of T cylindricity tolerance

orientation Tolerances

PARALLELISM The tolerance zone is limited by two parallel planes a distance apart. The planes are parallel to the datums and in the direction specified Direction specified Parallelism tolerance of a line related to a datum system

PARALLELISM The tolerance zone is limited by a cylinder of diameter t , parallel to the datum, if the tolerance value is preceded by the symbol Parallelism tolerance of a line related to a datum line

PARALLELISM Each extracted (actual) line shall be contained between two parallel lines 0,02 apart parallel to datum A and lying in a plane parallel to datum B Parallelism tolerance of a line related to a datum system

prependicularity The tolerance zone is limited by two parallel planes a distance apart and perpendicular to the datum Perpendicularity tolerance of a line related to a datum line

prependicularity The tolerance zone is limited by two parallel planes a distance t apart. The planes are perpendicular to the datum A and parallel to datum B Perpendicularity tolerance of a line related to a datum system

prependicularity The tolerance zone is limited by a cylinder of diameter perpen dicular to the datum if the tolerance value is preceded by the symbol Perpendicularity tolerance of a line related to a datum surface

Angularity a) Line and datum line in the same plane: The tolerance zone is limited by two parallel planes a distance t apart and inclined at the specified angle to the datum. Angularity tolerance of a line related to a datum line

Angularity b) The tolerance zone is limited by two parallel planes a distance t apart and inclined at the specified angle to the datum. The considered line and the datum line are not in the same plane Angularity tolerance of a line related to a datum line

Angularity The tolerance zone is limited by two parallel planes a distance t apart and inclined at the specified angle to the datum Angularity tolerance of a line related to a datum surface

Angularity The tolerance zone is limited by a cylinder of diameter t if the tolerance value is preceded by the symbol . The cylindrical tolerance zone is parallel to a datum plane B and inclined at the specified angle to the datum plane A Angularity tolerance of a line related to a datum surface

location Tolerances

position The tolerance zone is limited by a sphere of diameter t if the tolerance value is preceded by the symbol S. The center of the spherical tolerance zone is fixed by theoretically exact dimensions with respect to the datums A, B and C Position tolerance of a point

position The tolerance zone is limited by two parallel planes a distance t apart and symmetrically disposed about the center line. The center line is fixed by theoretically exact dimensions with respect to datums A and B. The tolerance is specified in one direction only. Position tolerance of a line

position The tolerance zone is limited by two pairs of parallel planes a distance 0,05 and 0,2 apart respectively and symmetrically disposed about the theoretically exact position. The theoretically exact position is fixed by theoretically exact dimensions with respect to the datums C, A and B. The tolerance is specified in two directions with respect to the datums. Position tolerance of a line

position Position tolerance of a line

position The tolerance zone is limited by a cylinder of diameter t if the tolerance value is preceded by the symbol . The axis of the tolerance cylinder is fixed by theoretically exact dimensions with respect to the datum s C, A and B Position tolerance of a line

position The tolerance zone is limited by two parallel planes a distance t apart and symmetrically disposed about the theoretically exact position fixed by theoretically exact dimensions with respect to the datums A and B Position tolerance of a flat surface or a median p lane

Concentricity The tolerance zone is limited by a circle of diameter t; the tolerance value shall be preceded by the symbol . The center of the circular tolerance zone coincides with the datum point Concentricity tolerance of a point

coaxiality The tolerance zone is limited by a cylinder of diameter t; the tolerance value shall be preceded by the symbol . The axis of the cylindrical tolerance zone coincides with the datum Coaxiality tolerance of an axis

symmetry The tolerance zone is limited by two parallel planes a distance t apart, symmetrically disposed about the median plane, with respect to the datum. Symmetry tolerance of a median plane

Runout Tolerances

Circular runout The tolerance zone is limited within any cross-section perpendicular to the datum axis by two concentric circles with a difference in radii of t, the centers of which coincides with the datum Circular run-out tolerance radial

Circular runout Run-out usually applies to complete features, but could be applied to a restricted part of a feature Circular run-out tolerance radial

Circular runout The tolerance zone is limited to any cylindrical section by two circles with a distance t apart lying in the cylindrical section, the axis of which coincides with the datum Circular run-out tolerance axial

Circular runout Circular The tolerance zone is limited within any conical section b y two circles a distance t apart, the axes of which coincide with the datum. Circular run-out tolerance in any direction

Circular runout The tolerance zone is limited within any conical section of the specified angle by two circles a distance t apart, the axes of which coincide with the datum Circular run-out tolerance in a specified direction

Total runout The tolerance zone is limited by two coaxial cylinders with a difference in radii of t, the axes of which coincide with the datum Total radial run-out tolerance

Total runout The tolerance zone is limited by two parallel planes a distance t apart and perpendicular to the datum Total axial run-out tolerance