| After construction, the
part is manufactured on the basis of the technical drawing. This is
accompanied by deviations and deformations. They can be caused by the
manufacturing machine, the external temperature, material defects and many
other effects.
The geometric elements of the manufactured
part along with the deviations are called actual shape or real
geometric elements.
|
Real geometry of the
part with manufacture-
related deviations
|
In addition to the
dimensional tolerances, the design engineer can also enter other tolerances
in the drawing:
 Form
tolerances serve for checking the dimensional deviation, in the above
example for checking the straightness of all lines of the bottom area
lying in parallel to the drawing plane.
- Positional tolerances serve for checking the
direction, location or runout. A list of all form and position tolerances
and the relevant entries on the drawing are shown on the right.
|
List of the form and position
tolerance symbols according to DIN ISO 1101: |
|
Form
 |
Straightness |
|
|
Flatness |
|
|
Roundness |
|
|
Cylindricity |
|
|
Line profile |
|
|
Surface profile |
|
Position
|
|
Tilt |
|
|
Position |
|
|
Coaxiality |
|
|
Symmetry |
|
|
Parallelism |
|
|
Perpendicularity |
|
 |
