English to Italian Tech/Engineering Other disegni industriali/tolleranze (nell\'ambito di specifica tecnica relativa a pezzi per auto)

4 Evaluation of abstract (unreal) features
Evaluation of features in accordance with the table shown below is theoretical. For practical reasons, one often departures from the theoretical evaluation when establishing a feature. In many cases an expanding or slightly tapered mandrel can be used instead of an inscribed cylindrical mandrel when aligning a feature against the real cylinder surface of a hole. A shrink mandrel (tensioning sleeve) can be utilized as circumscribed cylinder for a shaft.