photo credit: Chris Yarzab

Continuing the article written by Gianluca Gaggioli published on ‘Organizazione Qualità on September, 21^st, 2011 about the norm UNI EN ISO 8015  Geometrical Specifications of the products(GPS) – Basic principles – concepts, principles and rules’, herewith we would like to analyze some of the mentioned aspects.

The norm defines the principles, the general rules for the application of the ‘dimensional tolerances’ and addressing for the specific matter to the norms devoted to the various types of products realized through different productive technologies.

 

The norm finds its sector of application in all technical documents  and its relatives necessary to the realization of the manufactured product and defines in particular:

–          linear quotes and their tolerances

–          angular quotes and their tolerances

–          geometrical tolerances .

 

These are  necessary to define the following aspects:

–          dimension

–          form

–          orientation

–          position.

 

The norm ‘UNI ISO 8015, ED. ’89 (1)’ introduces the ‘ principle of dependence’ among the tolerances in order to foresee the limitation of dependence among the geometrical dependences and the tolerances of form and position. This can be seen for example when only the dimensional tolerances are indicated, and for the effect of the previous edition of the norm, the changes of of form and position are obliged to remain within the dimensional tolerances that are indicated.

 

The norm ‘UNI ISO 8015, ED. ’89 (1)’ introduces the ‘principle of independence’.

 

This principle is defined by the norm: ’Every dimensional  or geometrical prescription specified on a design must be respected in itself in an independent way, except if a particular relation is specified. ‘UNI ISO 8015, ED. ’89 (1)’

 

As stated above, if specific indications are missing, the tolerances must be applied without considering the dimension of the piece, and the prescriptions (dimensional and geometrical) will be treated as independent one from the other.

 

According to this principle all the deviations of form are no more limited by the dimensional tolerances.

 

Therefore all the technical documentation for which the principle of independence is applied must be identified properly with the following indication: Tolerances according  UNI ISO 8015.

 

The same norm foresees, that in absence of this indication, what is indicated in the previous norm in force is valid, that is ‘ ‘In absence of specific indications of norms regarding the principles of attributing of the tolerances or of the methods of verification of the same norms, the dimensional tolerances may limit also some deviations of form and/or of position.

 

In the next chapters the various types of tolerances expressed the following mentioned norms will be deeper studied and classified.

UNI EN ISO 8015 Geometrical product specifications (GPS) – Fundamentals – Concepts, principles and rules

UNI ISO 5459  Geometrical product specifications (GPS) – Geometrical tolerancing – Datums and datum systems

UNI EN ISO 1101  Geometrical Product Specifications (GPS) – Geometrical tolerancing – Tolerances of form, orientation, location and run-out

UNI EN ISO 2692  Geometrical product specifications (GPS) – Geometrical tolerancing – Maximum material requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR)

UNI ISO 22768  General tolerances. Tolerances for linear and angular dimensions without individual tolerance indications.

UNI ISO 22768 Geometrical tolerances for features without individual tolerance indications.

UNI EN ISO 1302  Geometrical Product Specifications (GPS) – Indication of surface texture in technical product documentation

UNI EN 755-1 Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 1: Technical conditions for inspection and delivery

UNI EN 755-2  Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 2: Mechanical properties

UNI EN 755-3. Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 3: Round bars, tolerances on dimensions and form

UNI EN 755-4. Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 4: Square bars, tolerances on dimensions and form

UNI EN 755-5 Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 5: Rectangular bars, tolerances on dimensions and form

UNI EN 755-6  luminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 6: Hexagonal bars, tolerances on dimensions and form

UNI EN 755-7  Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 7: Seamless tubes, tolerances on dimensions and form

UNI EN 755-8 Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 8: Porthole tubes, tolerances on dimensions and form

UNI EN 755-9 . Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Part 9: Profiles, tolerances on dimensions and form

UNI EN 12020-2  Aluminium and aluminium alloys – Extruded precision profiles in alloys EN AW-6060 and EN AW-6063 – Part 2: Tolerances on dimensions and form

UNI ISO 8062 Castings. System of dimensional tolerances.

UNI ISO 8062-1 Geometrical product specifications (GPS) – Dimensional and geometrical tolerances for moulded parts – Part 1: Vocabulary

UNI ISO 8062-3 Geometrical product specifications (GPS) – Dimensional and geometrical tolerances for moulded parts – Part 3: General dimensional and geometrical tolerances and machining allowances for castings

UNI ISO 8062  Castings. System of dimensional tolerances.

UNI EN ISO 9445-1 Continuously cold-rolled stainless steel – Tolerances on dimensions and form – Part 1: Narrow strip and cut lengths

UNI EN ISO 9445-2  Continuously cold-rolled stainless steel – Tolerances on dimensions and form – Part 2: Wide strip and plate/ sheet

UNI EN 10051 Continuously hot-rolled strip and plate/ sheet cut from wide strip of non-alloy and alloy steels – Tolerances on dimensions and shape

UNI EN 10029  Hot-rolled steel plates3 mm thick or above – Tolerances on dimensions and shape

FICHE UIC 800-51 OR  Ecarts admissibles pour cotes sans indication de tolérances dans les constructions soudées

FICHE UIC 800-55 OR  Ecarts admissibles sur cotes sans indication de tolérances dans les constructions soudées sur les éléments de construction en aluminium

Translated by Carmela Giordano