Tabella Gola Uni Iso 4755 [cracked] | Latest |

Informative Report: UNI ISO 4755 – Thread Run-Outs and Undercuts (Tabella Gola)

Option 2: Technical Blog / Forum Post (Bilingual: English + Italian)

Title: Tabella Gola UNI ISO 4755: Complete Guide to Thread Undercuts

Introduction: The UNI ISO 4755 standard (often searched as "tabella gola uni iso 4755") is the reference document for thread undercuts in metric fasteners. If you manufacture screws, bolts, or turned parts, this table is essential.

What is a "Gola" (Undercut)? A "gola" is a reduced diameter section located between the threaded portion and the unthreaded shank or shoulder. It allows the thread to be made fully effective right up to the head or shoulder.

Key Dimensions from the Table (Example Extract): tabella gola uni iso 4755

| Passo (Pitch) | Diametro Gola (Undercut Ø) | Larghezza (Width) | | :--- | :--- | :--- | | 0,5 mm | d - 0,2 mm | 0,8 mm | | 1,0 mm | d - 0,4 mm | 1,6 mm | | 1,5 mm | d - 0,6 mm | 2,4 mm | | 2,0 mm | d - 0,8 mm | 3,0 mm |

(d = nominal diameter of the thread)

How to use the table:

Identify the thread pitch (e.g., M10x1.5 → Pitch = 1.5mm).
Locate the corresponding undercut diameter (M10 - 0.6 = 9.4 mm).
Machine the groove to the specified width (2.4 mm).

Pro Tip: Always use the ISO 4755 undercut for aerospace and automotive components to avoid notch effects and fatigue failure.

Download the full table: [Link to PDF]

How to Measure the Gola (Quality Control)

If you receive a batch of bolts and need to verify they match the tabella gola UNI ISO 4755, follow these steps: Informative Report: UNI ISO 4755 – Thread Run-Outs

Use a Profile Projector or Optical Comparator: The groove is too small for standard calipers. An optical comparator projects the silhouette of the bolt thread at 10x to 50x magnification.
Check d₁ (Groove Diameter): Use a needle probe or a specialized groove micrometer. Ensure the diameter is less than the minor diameter of the thread but greater than the core diameter of the blank.
Check a (Groove Width): A simple thickness gauge or a custom GO/NO-GO ring gauge works best.
Check r (Radius): Visual comparison with a radius gauge. If the radius is too sharp (like a square notch), reject the part. If it is too large, the threaded length becomes too short.

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.

Why Does the "Gola" Exist?

Without a standardized undercut (groove), two problems occur: Identify the thread pitch (e

Stress Concentration: A sharp corner between the head/shank and the thread acts as a stress riser, leading to fatigue failure.
Interference: When threading into a hole with an internal thread (like a tapped blind hole), the incomplete thread at the start of the bolt might bottom out before the head clamps.

The gola solves both by providing a smooth, recessed relief.

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:

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.