GEOMETRIC TOLERANCES - Ch.1 - UNI EN ISO 8015
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Following Article published on Quality Organization on September 21, 2011, by Gianluca Gaggioli, relative to the norm " UNI EN ISO 8015 Geometrical product specifications (GPS) - Fundamentals - Concepts, principles and rules, " you want with the present, investigate aspects mentioned.
The legislation defines precisely the principles of the general rules for the application of the "tolerances", then specifically referring to other provisions devoted to the various types of products manufactured by different production technologies.
The rule finds its "scope" in all its technical documents and related necessary for the realization of an artifact, and define in particular:
- Linear dimensions and their tolerances;
- Angular Dimensions and their tolerances;
- Geometric tolerances.
These are necessary to define the following aspects:
- Size;
- Form;
- Orientation;
- Location.
The legislation "UNI ISO 8015, ed. '89 [1] [1] ", introduces the" principle of independence "between the tolerances, in order to prevent precisely limitations of dependence between the geometric tolerances and tolerances of shape and position. This occurs for example when they are shown the only dimensional tolerances, which due to the previous edition of the standard, forcing the deviations of form and position to remain within the same dimensional tolerances indicated.
The "UNI ISO 8015, ed. '89 [1] "introduces the" principle of independence ".
The latter is defined by the rule: "Each prescription or specified geometric dimensions on a drawing must be respected in itself independently, unless otherwise specified a particular relationship" (UNI ISO 8015 ed. '89) [1] 1 .
The above states that in the absence of specific guidance, the tolerances shall apply without regard to the size of the piece, and the requirements (dimensional and geometric) will be treated as independent of each other.
According to this principle all the deviations of the form are no longer limited by the dimensional tolerances.
Therefore, all technical documentation for which it applies the principle of independence, must be properly identified with the following indication: Tolerances according to ISO 8015.
The same rule provides that, in the absence of such indication, it is still necessary as written in the rule previously in force, ie, "In the absence of specific rules concerning the principles for the allocation of tolerances or methods of verification, dimensional tolerances can also restrict certain deviations of shape and / or position. "
In the following chapters, will be explored and classified the various types of tolerances expressed by the standards listed below.
[1] Retreat with replacement from the ed. 2011.
They cite the following regulations concerning tolerances applicable to the various products made with different technologies and materials:
UNI EN ISO 8015 - Technical drawings. Core Principles for the 'allocation of tolerances.
UNI ISO 5459 - Technical drawings. Indication of geometrical tolerances. References and reference systems for geometrical tolerances.
UNI EN ISO 1101 - Geometrical product specifications (GPS) - Indication of geometric tolerancing - Tolerances of form, orientation, location, and swing
UNI EN ISO 2692 - Geometrical product specifications (GPS) - Indication of geometric tolerancing - Maximum material requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR)
ISO 22768 Part 1 ^ - Tolerances for linear and angular dimensions without indication of specific tolerances.
ISO 22768 part 2 ^ - Tolerances for elements with no indication of specific tolerances
UNI EN ISO 1302 - Geometrical product specifications (GPS) - Indication of the state of the surfaces in the technical documentation of product.
UNI EN 755-1 Aluminium and aluminum alloys - Barre, tube and profiles - Part 1: Technical conditions for inspection and delivery.
UNI EN 755-2 Aluminium and aluminum alloys - Barre, tube and profiles - Part 2: Mechanical properties.
UNI EN 755-3 Aluminium and aluminum alloys - Barre, tube and profiles - Part 3: Round bars, tolerances on dimensions and form.
UNI EN 755-4 Aluminium and aluminum alloys - Barre, tube and profiles - Part 4: Square bars, tolerances on dimensions and form.
UNI EN 755-5 Aluminium and aluminum alloys - Barre, tube and profiles - Part 5: Rectangular bars, tolerances on dimensions and form.
UNI EN 755-6 Aluminium and aluminum alloys - Barre, tube and profiles - Part 6: Hexagonal bars, tolerances on dimensions and form.
UNI EN 755-7 Aluminium and aluminum alloys - Barre, tube and profiles - Part 7: Seamless tubes, tolerances on dimensions and form.
UNI EN 755-8 Aluminium and aluminum alloys - Barre, tube and profiles - Part 8: Extruded Tubes with chain bridge, tolerances on dimensions and form.
UNI EN 755-9 - Aluminium and aluminum alloys - Barre, tube and profiles - Part 9: Profiles, tolerances on dimensions and form.
UNI EN 12020-2 - Aluminium and aluminum alloys - Extruded precision profiles in alloys EN AW-6060 and EN AW-6063: Tolerances on dimensions and shape.
UNI ISO 8062 - Castings. System of dimensional tolerances.
BS ISO 8062-1 Geometrical product specifications (GPS) - Dimensional and geometrical tolerances of the pieces obtained from casting - Part 1: Vocabulary.
BS ISO 8062-3 Geometrical product specifications (GPS) - Dimensional and geometrical tolerances of the pieces obtained from casting - Part 3: Tolerances on dimensions and geometric processing and general allowances of the jets.
UNI ISO 8062 - Castings. System of dimensional tolerances
UNI EN ISO 9445-1 - Stainless steel cold-rolled continuously - Tolerances on dimensions and form - Part 1: strip and sheet.
UNI EN ISO 9445-2 - Stainless steel cold-rolled continuously - Tolerances on dimensions and form - Part 2: Fittings and wide strip.
UNI EN 10051 - Hot rolled sheet and strip in continuous, uncoated, of non-alloy and alloy steels - Tolerances on dimensions and form
UNI EN 10029 - Hot rolled steel, thickness = or> of 3 mm. Tolerances on dimensions, shape and mass.
UIC Leaflet 800-51 OR - Permissible deviations for shares without indication of tolerances for welded steel structures
UIC Leaflet 800-55 OR - Permissible deviations for shares without indication of tolerances for welded structures in aluminum
About the Author: Umberto Bartolini
January 19, 2012