Tabella Gola Uni Iso 4755 -

| Standard | Content | |----------|---------| | ISO 4755 | Same as UNI ISO 4755 (international version) | | DIN 76-1 | Very similar – thread run-outs and undercuts for metric threads | | UNI 9460 (obsolete) | Older Italian standard, now replaced by UNI ISO 4755 | | ISO 3506 | Mechanical properties – references undercuts for fatigue life |

If you are inspecting screws:

If you need the exact engineering drawing (blueprints), you should consult the ISO 4755:2000 official document directly, as it contains the precise geometric tolerances (angles and radii) required for manufacturing.

La tabella GOLA secondo la norma UNI ISO 4755! Ecco una guida utile per comprendere e utilizzare questa tabella.

Cos'è la tabella GOLA?

La tabella GOLA è una tabella di tolleranze per le dimensioni di fori e alberi (o assi) secondo la norma UNI ISO 4755. Questa norma internazionale fornisce un sistema di tolleranze per le dimensioni di pezzi meccanici, al fine di garantire l'intercambiabilità e la corretta funzionalità dei componenti.

Come si legge la tabella GOLA?

La tabella GOLA è composta da diverse colonne che indicano:

I valori di tolleranza sono espressi in micron (μm) o in millimetri (mm). tabella gola uni iso 4755

Come si utilizza la tabella GOLA?

Per utilizzare la tabella GOLA, segui questi passaggi:

Esempio

Supponiamo di avere un foro con dimensione nominale di 50 mm e di voler applicare una tolleranza di H7. Consultando la tabella GOLA, possiamo leggere:

| DN | Tolleranza foro | Tolleranza albero | Gola | | --- | --- | --- | --- | | 50 | +0,000 / +0,025 | -0,050 / -0,025 | 0,025 |

In questo caso, il foro può avere una dimensione compresa tra 50,000 mm e 50,025 mm, mentre l'albero può avere una dimensione compresa tra 49,950 mm e 49,975 mm.

Conclusione

La tabella GOLA secondo la norma UNI ISO 4755 è uno strumento utile per determinare le tolleranze per le dimensioni di fori e alberi. Seguendo i passaggi descritti sopra, puoi utilizzare la tabella per garantire l'intercambiabilità e la corretta funzionalità dei componenti meccanici. | Standard | Content | |----------|---------| | ISO

In the cold, sterile light of the Quality Control lab, Marco stared at the blueprint until the lines blurred. The part on his desk—a high-tensile steel drive shaft—was failing every stress test. It was a masterpiece of machining, except for one fatal flaw: the threads met the shoulder at a sharp, jagged angle. "Stress concentration," he muttered, rubbing his eyes.

He pulled a worn, oil-stained manual from his shelf and flipped to the section marked UNI ISO 4755.

"The Tabella Gola," his mentor, Old Man Moretti, used to call it. To the uninitiated, it was just a table of dimensions for "Thread Undercuts for ISO Metric External Threads." But to a machinist, it was the secret to survival.

The table didn't just provide numbers; it provided the geometry of relief. It dictated the exact width and depth of the groove—the gola—that must be carved into the metal where the thread ended. This tiny, vanished ring of steel was what allowed the nut to sit perfectly flush and, more importantly, ensured the shaft wouldn't snap under pressure.

Marco recalibrated the lathe. He followed the coordinates for a 1.5mm pitch: a depth of 0.5mm, a radius of 0.6mm. As the carbide tip bit into the steel, a perfect, smooth radius formed—a "Type A" undercut, exactly as the ISO standard demanded.

He ran the new part through the hydraulic press. The needle climbed, past the previous breaking point, into the green. The shaft held. By respecting the "Gola," Marco hadn't just followed a rule; he had turned a point of failure into a point of strength.

Standardization, he realized, wasn't about being rigid—it was about making sure the smallest details could carry the heaviest loads.

The UNI ISO 4755 “tabella gola” is not a mere reference—it is a quality assurance tool. For designers, using this table ensures interchangeability. For machinists, it defines the cutting tool path. For inspectors, it provides the acceptance limits. If you need the exact engineering drawing (blueprints),

Whether you are manufacturing a standard M8 screw or a custom M30 stud, consulting the UNI ISO 4755 undercut table is a small step that prevents big failures. Always specify the standard clearly and verify the undercut with appropriate gauges.

Reference:
UNI ISO 4755:2004 – Fasteners – Bolts, screws and studs – Undercuts for metric threads (Italian National Standard, identical to ISO 4755:1983)

Related Standards:

| Pitch P (mm) | Undercut width g (mm) | Undercut diameter (approx.) | |--------------|------------------------|-------------------------------| | 0.5 | 0.6 | minor dia - 0.2 mm approx. | | 0.7 | 0.8 | ... | | 1.0 | 1.1 | ... | | 1.25 | 1.4 | ... | | 1.5 | 1.6 | ... | | 1.75 | 1.9 | ... | | 2.0 | 2.2 | ... |

Note: Exact diameters depend on whether the undercut is for external or internal thread. The standard provides distinct values.

Since the user asked for "Gola" (Groove), it is crucial to distinguish between the End Chamfer and the Thread Run-Out.

If you need the Run-Out Groove (Gola di fine filetto - ISO 4757): The values are based on the Pitch ($P$).