Tabella Gola Uni Iso 4755 Instant

The UNI ISO 4755 standard defines dimensions for thread undercuts ( ) based on thread pitch (

) for external metric fasteners, ensuring proper clearance. These undercuts are utilized to allow full thread engagement up to a shoulder, typically applying a 30° transition angle and h12/h13 tolerances. View the technical document on MEC360. ISO-4755-1983.pdf - iTeh Standards tabella gola uni iso 4755

Applications of the Tabella Gola Uni

The Tabella Gola Uni, as specified under the UNI ISO 4755 standard, finds applications in various industries, including but not limited to: The UNI ISO 4755 standard defines dimensions for

Mechanical Engineering: For the design and manufacturing of mechanical components.
Aerospace: Where precision and reliability are critical.
Automotive: In the production of vehicle parts and accessories.

C. Automotive Engine Building

Connecting rod bolts and cylinder head bolts almost always conform to an undercut standard (often derived from ISO 4755). When rebuilding an engine, mechanics look for this groove to confirm they are using OEM-grade fasteners, not cheap hardware store substitutes. Applications of the Tabella Gola Uni The Tabella

How to Read This Table

Thread Size (d): The nominal diameter of the bolt.
Groove Diameter (d₁): The reduced diameter at the bottom of the undercut. This must be smaller than the minor diameter of the thread to ensure the groove provides real relief.
Groove Width (a): The axial length of the undercut (how long the groove is).
Radius (r): The transition fillet radius at the corners of the groove. A larger radius distributes stress better.

1. Scope of the Standard

UNI ISO 4755 (identical to ISO 4755) specifies the dimensions of thread run-outs and thread undercuts for ISO metric threads (according to ISO 261 – general purpose metric threads).

The so-called “tabella gola” (Italian for “undercut table”) is the core part of this standard. It provides standardized dimensions for the groove (undercut) machined at the end of a threaded portion to allow a threaded part to screw fully against a shoulder or to facilitate thread cutting tool run-out.