05. Geometric tolerances

1.  WORKING DRAWINGS

2.  SURFACE CHARACTERISTICS

3.  DIMENSIONAL TOLERANCES

4.  FITS

5.  GEOMETRIC TOLERANCES

6.  DIMENSIONING

7.  THREADED FASTENING

8.  SHAFT AND PIPE JOINERS

9.  BEARINGS

10. GEARS 1: DEFINITION

11. GEARS 2: BEVEL AND HELICAL

12. BELTS AND CHAINS

13. WELDED JOINTS AND RIVETS

14. INDUSTRIAL DESIGN METHODOLOGY

15. SIMULATION

5. GEOMETRIC TOLERANCES

GEOMETRIC TOLERANCES

Industrial Drawing CC 2015 Ramón Rubio

DEFINITIONS | EXAMPLES

Sometimes, dimensional tolerances are not enough to ensure the function of a part in a mechanism.




So we add some information that complements dimensions. It is known as GD&T (Geometric Dimensioning & Tolerancing)




Let us see an example of WHY geometric tolerances are so important. We design a table and the height has a tolerance. Assume all 4 legs are cut at the same time.




As the table height is dimensioned, the following table would pass inspection.




But …look at the table! It’s not flat, but inclined. Despite that, the table would pass.




You can solve that, by using GD&T. •  The table may be any height between 26 and 28 inches. •  The table top must be flat within 1/16. (±1/32)

26

.06




Feature Control Frame: It’s the main part of GD&T




The arrow of the frame:

1. Pointing at the surface: Indicates the reference surface

2. If it is an extension of the dimension line, it will indicate the axis or symmetry plane

3. Pointing at the axis means that the tolerance for all the elements is related to that axis.




FORM > Straightness (Rectitud) The straightness of the feature must be within .005 tolerance zone.




FORM > Straightness (Rectitud)




FORM > Flatness (Planicidad) The tolerance zone is a zone held between two parallel planes a distance “t” apart




The real curve must be between two circumferences whose radii difference is the tolerance.

FORM > Circularity (Redondez)




FORM > Cilindricity (Cilindricidad) The real cylinder must be between two cylinders whose radii difference is the tolerance.




ORIENTATION > Parallelism (Paralelismo) The tolerance zone is a zone held between two parallel planes parallel to the datum plane and a distance “t” apart from each other




The tolerance zone is a zone within a cylinder of diameter “t” perpendicular to the datum plane

ORIENTATION > Perpendicularity (Perpendicularidad)




ORIENTATION > Perpendicularity




ORIENTATION > Angularity (inclinación) The tolerance zone is held between two parallel planes inclined at the specified angle to the datum plane and separates “t” units from each other.




LOCATION > Positional (Posición) The tolerance zone is a zone within a circle, cylinder or sphere of diameter “t” having its centre at the theoretically exact location.




LOCATION > Coaxiality (Coaxialidad) The tolerance zone is a zone within a cylinder of diameter “t” whose axis agrees with the datum axial straight line.




LOCATION > Symmetry (Simetría) The tolerance zone is held between two parallel planes a distance “t” apart from each other and arranged symmetrically to the datum median plane.




RUN OUT > Circular run-out The tolerance is a zone between two concentric circles whose centres agree with the datum axial straightline on any measuring plane normal to the datum axial straightline. They are a distance “t” apart from each other in the radial direction.




RUN OUT > Total run-out The tolerance is a zone between two coaxial cylinders having axes agreeing with the datum axial straightline and a distance “t” apart from from each other in the radial direction.

1.  WORKING DRAWINGS

2.  SURFACE CHARACTERISTICS

3.  DIMENSIONAL TOLERANCES

4.  FITS

5.  GEOMETRIC TOLERANCES

6.  DIMENSIONING

7.  THREADED FASTENING

8.  SHAFT AND PIPE JOINERS

9.  BEARINGS

10. GEARS 1: DEFINITION

11. GEARS 2: BEVEL AND HELICAL

12. BELTS AND CHAINS

13. WELDED JOINTS AND RIVETS

14. INDUSTRIAL DESIGN METHODOLOGY

15. SIMULATION

5. GEOMETRIC TOLERANCES

05. Geometric tolerances

Engineering

Transcript of 05. Geometric tolerances