ISOtoleranssi

ISOtoleranssi refers to the standardized system of dimensional and geometrical tolerances used in engineering and manufacturing, established by the International Organization for Standardization (ISO). This system, primarily defined in ISO 286, provides a common language for specifying acceptable variations in the size and form of manufactured parts. The core of the system is the designation of a nominal size, a tolerance zone, and an accuracy grade.

The tolerance zone is defined by an upper deviation and a lower deviation from the nominal size. These deviations determine the maximum and minimum allowable dimensions of a part. The accuracy grade, denoted by a number (e.g., IT5, IT6, IT7), specifies the width of this tolerance zone. Lower numbers indicate tighter tolerances and higher precision.

In addition to size tolerances, the ISO system also addresses geometrical tolerances, which control the form, orientation, and location of features on a part. These include flatness, straightness, circularity, perpendicularity, and position, among others. These geometrical tolerances are crucial for ensuring that mating parts function correctly and assemblies fit together as intended.

The adoption of ISOtoleranssi globally facilitates international trade and ensures interchangeability of parts manufactured by different companies or in different countries. It helps to reduce manufacturing costs by avoiding overly tight tolerances where they are not needed and by enabling mass production with consistent quality. Understanding and applying ISOtoleranssi is fundamental for designers, engineers, and quality control professionals in modern manufacturing.