Gola Uni Iso 4755 [work]

A specific radius is defined for the corner of the groove to avoid sharp edges that act as stress raisers. Comparison with Related Standards

Previously used in Italy for incomplete threads and undercuts; however, the portion regarding undercut dimensioning was withdrawn in 2009 and replaced by the UNI ISO 4755 standard . gola uni iso 4755

ISO 4755 does not define underhead collar (gola) dimensions. Always reference a supplementary product standard or engineering drawing for complete Gola geometry. A specific radius is defined for the corner

The ISO 4755 standard provides a detailed table of dimensions in millimeters, directly tied to the and nominal diameter of the fastener. Standard Requirement Undercut Diameter ( ) gola uni iso 4755

| Property | Requirement | |----------|-------------| | Width across flats (s) | Tolerance: h11 to h14 depending on product grade | | Head height (k) | Tolerance: h14 for formed heads | | Wrenching interface | Hexagon external (or internal if specified) | | Reference edge | Underhead fillet or Gola shoulder radius ≤ 0.5× s |