Tabella Gola Uni Iso 4755 Online

UNI ISO 4755 standard specifies the dimensions for thread undercuts gola di scarico

) for fasteners with external metric ISO threads. This "feature" is

a machined groove located at the end of the threaded portion of a bolt or screw, where it meets a shoulder or collar ISO - International Organization for Standardization Key Features of the ISO 4755 Undercut

: It provides clearance for the assembly of mating parts (like a nut or a flange) to sit flush against the fastener's shoulder, as threads cannot be cut perfectly to the very edge of a solid wall. : The undercut dimensions are determined by the thread pitch ( Diameter ( : Typically at least smaller than the thread's minor diameter. : Generally recommended to be between for normal applications. Transition : It often includes a radius or chamfer (e.g., 45 raised to the composed with power

) to reduce stress concentration at the transition between the thread and the shoulder. Common Applications This feature is standard in mechanical engineering for: Precision fasteners where a tight, flush fit against a surface is required. Automated assembly

, ensuring no interference from incomplete "run-out" threads. for common thread sizes like M6 or M10?

The UNI ISO 4755 standard (equivalent to ISO 4755:1983) specifies the required form and dimensions for thread undercuts (Italian: gole di scarico) on externally threaded fasteners like bolts and screws. These undercuts are used to provide clearance for a mating part (such as a plug or sealing element) to sit flush against a shoulder when the thread cannot be run all the way to the end. Key Specifications of ISO 4755

The standard provides a tabulated set of dimensions in millimeters, which are determined by the thread pitch ( ) and the nominal diameter ( ) of the fastener. Undercut Diameter (

): The diameter of the recessed portion, typically smaller than the thread's minor diameter to ensure clearance. Undercut Width (

): The axial length of the relief section. Standard relief is often between one and three full thread pitches.

Transition Angle: The standard specifies the shape and transition between the threaded portion and the undercut, generally requiring a minimum transition angle of 30∘30 raised to the composed with power where applicable. Radii (

): Specifies the corner radii to minimize stress concentrations in the fastener. Typical Dimensioning Table (Summary)

The official ISO 4755 table provides specific values for each pitch. Below is a general guide on how dimensions are typically derived: Reference Formula/Requirement Diameter ( )

Linked to thread minor diameter to ensure mating part clearance. Width ( ) (Standard) or Radius ( )

Sized to avoid sharp edges while maintaining structural integrity.

For detailed engineering drawings or manufacturing, you can find complete technical PDFs and tables through specialized fastener resources like Fasteners.eu or official ISO portal snippets. g., M10 or M12)?

UNI ISO 4755 standard is a fundamental reference in industrial design for the geometric definition of thread undercuts (known in Italian as gole di scarico

) for fasteners with external metric ISO threads. These undercuts are critical features used to ensure a "complete" thread runs all the way to a shoulder, allowing mating parts like plugs or screws to sit perfectly flush against a surface. iTeh Standards Functional Importance of Under-cuts

In mechanical turning, it is impossible for a cutting tool to create a perfect thread right up to a vertical shoulder without a relief zone. The undercut provides: Tool Clearance:

Space for the threading tool to "run out" or disengage safely at the end of the pass. Flush Assembly:

Prevents interference from incomplete thread crests, ensuring the screw head or plug shoulder makes full contact with the mating surface. Stress Management:

Properly dimensioned undercuts, typically featuring a 30° transition angle, help manage mechanical stress at the transition point. WordPress.com Technical Dimensions (UNI ISO 4755) The standard provides specific dimensions based on the thread pitch ( . Key parameters include the undercut diameter ( ), the width ( ), and the transition radius ( iTeh Standards Thread Pitch ( Undercut Diameter ( is approximately equal to 3 cap P Data source: ISO 4755:1983 Dimensional Table Design Considerations Transition Angle:

The standard specifies a minimum angle of 30° for the transition between the undercut and the thread. Relationship with Other Norms: While UNI ISO 4755 covers undercuts for external threads,

is often cited for incomplete thread run-outs, and they are frequently used together in technical manuals. Application:

These dimensions are recommended for general-purpose fasteners unless a specific product standard (e.g., for specialized bolts) mandates different proportions. Fasteners Engineering GOLE DI SCARICO

Guida Definitiva alla Tabella Gola UNI ISO 4755: Dimensioni e Progettazione Nel mondo della progettazione meccanica, la gola di scarico tabella gola uni iso 4755

(thread undercut) è un dettaglio spesso sottovalutato ma fondamentale per garantire il corretto montaggio e la durata dei componenti filettati. La normativa di riferimento per le filettature esterne metriche ISO è la UNI ISO 4755 Cos'è la Gola di Scarico UNI ISO 4755?

La norma specifica la forma e le dimensioni delle gole di scarico per viti, bulloni e prodotti similari. La sua funzione principale è permettere a un componente accoppiato, come un tappo o una spalla rettificata, di andare a battuta perfettamente contro la faccia del pezzo, eliminando l'interferenza causata dal tratto di filetto incompleto. Tabella Dimensionale UNI ISO 4755 (Estratto) Le dimensioni della gola dipendono direttamente dal passo della filettatura (P) . Di seguito i valori principali espressi in millimetri: Diametro Gola ( Raggio (r)

: Diametro del fondo della gola (tolleranza h12 o h13 per diametri piccoli). : Corrisponde tipicamente a Angolo di transizione 30 raised to the composed with power Perché è fondamentale in officina? Montaggio a filo

: Senza la gola, la "fuga" del filetto impedisce al dado o alla flangia di toccare la spalla del bullone. Riduzione delle tensioni

: Una gola ben raccordata riduce l'effetto intaglio, migliorando la resistenza a fatica del componente. Lavorazione CNC

: Facilita l'uscita dell'utensile durante la tornitura o la rettifica. Differenza tra UNI ISO 4755 e DIN 76 ISO-4755-1983.pdf - iTeh Standards

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 standard (equivalent to the international ISO 4755) specifies the required form and dimensions for thread undercuts on bolts, screws, and similar externally threaded products. These undercuts are used to provide clearance for tools during machining or to ensure a flush fit for mating components. Technical Specifications for Thread Undercuts

The standard provides specific dimensions based on the thread pitch (

). Below are the typical recommended dimensions in millimeters: Undercut Diameter ( Undercut Length ( 0.25 0.4 0.5 0.7 0.8 1.0 1.25 1.5 1.75 2.0 Table data based on standard ISO 4755 dimensions. Key Design Rules Undercut Length ( ): Generally calculated as approximately times the thread pitch ( Transition Angle: A minimum transition angle of 30∘30 raised to the composed with power is typically maintained for the undercut profile.

Application: These dimensions are recommended unless a specific product standard (like those for specialized shoulder screws) provides its own undercut requirements. ISO-4755-1983.pdf - iTeh Standards

The UNI ISO 4755 standard specifies the form and dimensions of thread undercuts (Italian: gola di scarico) for fasteners with external metric ISO threads. These undercuts are essential for ensuring a flush fit when a screw or bolt is tightened against a surface, as they provide clearance for the non-threaded transition zone. 🛠️ Purpose of the Undercut

In manufacturing, a thread cannot be cut perfectly to the very end of a shoulder. The "run-out" section is often slightly larger than the pitch diameter, which prevents a nut or a flat surface from sitting flush.

Flush Mounting: Allows the head or shoulder of the fastener to seat fully against the workpiece.

Stress Reduction: Provides a smooth transition to reduce stress concentrations at the neck.

Manufacturing Ease: Simplifies the tool exit path during the threading process. 📐 Geometric Dimensions (Summary Table)

The dimensions of the undercut depend primarily on the thread pitch (

). Below is a summary of the standard values defined in ISO 4755. (Dia. max) (Width min) (Width max) (Radius min) 0.5 0.75 1.0 1.25 1.5 2.0 2.5 : Nominal thread diameter. : Maximum diameter of the undercut. : Range of the undercut width. : Minimum fillet radius to avoid sharp corners. 🏗️ Design Rules According to SIST ISO 4755:

Transition Angle: The angle between the undercut and the threaded portion should typically be at least 30°. UNI ISO 4755 standard specifies the dimensions for

Surface Finish: The undercut surface should ideally be smoother than the thread itself to prevent crack initiation.

Applicability: This standard is recommended for bolts, screws, and plugs unless a specific product standard (like DIN 7965) mandates a different geometry. 🔍 Related Standards

UNI 5709: Older Italian national standard for thread undercuts, now largely superseded by ISO 4755.

DIN 76-1: The German equivalent often used in European engineering drawings for thread run-outs and undercuts.

ISO 3506: Useful if you are working with stainless steel fasteners and need to check mechanical property requirements alongside geometry.

If you are modeling this in CAD, would you like a step-by-step guide on how to create this feature in SolidWorks or AutoCAD?

While "Tabella Gola" translates to "Groove Table," the reference to ISO 4755 specifically points to the international standard for "Fasteners — Product design rules for tapping screws and metal drive screws."

Here is a breakdown of what this standard covers, why the "Gola" (groove/notch) matters, and how the data is typically structured.

Typical parameters in the table:

Passo (P) – Thread pitch (mm)
g (min) – Width of undercut (mm)
d₂ – Diameter of undercut (normally = minor diameter of internal thread or slightly smaller for external threads)
r (max) – Radius at the bottom of the undercut

8. Conclusion

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.

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:

ISO 965-1: Metric thread tolerances
DIN 76-1: Undercuts for metric threads according to ISO (similar but not identical)

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

La UNI ISO 4755 è la norma tecnica di riferimento che stabilisce la geometria e le dimensioni delle gole di scarico per la bulloneria e altri elementi con filettatura metrica ISO esterna. Questa lavorazione è fondamentale nella meccanica di precisione per permettere il corretto accoppiamento a battuta tra componenti filettati e per facilitare l'uscita dell'utensile durante la tornitura. Cos'è la Gola di Scarico UNI ISO 4755?

Una gola di scarico (o "scarico del filetto") è un'incisione anulare praticata alla fine di un tratto filettato, solitamente in corrispondenza di uno spallamento. Senza di essa, i filetti incompleti (filetti di uscita) impedirebbero a una madrevite o a un dado di avvitarsi completamente fino alla superficie d'appoggio.

La norma UNI ISO 4755 (corrispondente alla versione internazionale ISO 4755:1983) definisce una forma standard che ottimizza la resistenza meccanica e la facilità di produzione. Tabella Dimensionale UNI ISO 4755 (Estratto)

Le dimensioni della gola dipendono esclusivamente dal passo della filettatura (P). Di seguito sono riportati i valori principali per i passi più comuni: Diametro Gola ( Larghezza ( Larghezza ( 0,5 0,7 0,8 1,0 1,25 1,5 1,75 2,0 Legenda dei simboli: : Diametro nominale della filettatura. : Diametro del fondo della gola.

: Distanza minima tra l'ultimo filetto completo e lo spallamento. : Larghezza massima della gola (circa 3 volte il passo).

: Raggio di raccordo per evitare intagli che causerebbero rotture a fatica. Importanza nella Progettazione Meccanica ISO-4755-1983.pdf - iTeh Standards

La norma UNI ISO 4755 definisce dimensioni e forme delle gole di scarico per filettature metriche ISO esterne, con parametri che variano in base al passo del filetto. Queste geometrie, essenziali per la lavorazione, includono diametri ridotti (

) e larghezze specifiche per garantire il corretto posizionamento degli elementi di fissaggio. Per una guida dettagliata all'uso in officina, consultare l'estratto tecnico di WordPress.com UNI ISO 4755 - WordPress.com

The Essential Guide to UNI ISO 4755: Mastering Thread Undercuts

In precision engineering, the smallest details often determine the success of a mechanical assembly. One such detail is the thread undercut (or gola di scarico), governed by the UNI ISO 4755 standard.

Whether you’re a machinist or a mechanical designer, understanding this "tabella gola" is critical for ensuring that bolts, screws, and plugs sit flush against their mating surfaces without interference. What is UNI ISO 4755? Passo (P) – Thread pitch (mm) g (min)

The UNI ISO 4755 standard specifies the form and dimensions for thread undercuts on fasteners with external metric ISO threads. It provides a standardized "relief groove" at the end of a threaded section, allowing a cutting tool to exit cleanly and ensuring a flat seat for the mating component. Why are Undercuts Necessary?

Tool Clearance: They provide space for the thread-cutting tool to finish its pass without crashing into a shoulder.

Flush Fitting: Without an undercut, a small radius or incomplete thread often remains at the base of a shaft, preventing a nut or part from seating perfectly flat.

Stress Management: Properly designed undercuts can reduce stress concentrations at the transition point of a fastener. Key Dimensions in the UNI ISO 4755 Table

The standard provides specific dimensions (in mm) tied to the thread pitch (

). Key parameters found in technical tables like Fasteners.it include:

(Undercut Diameter): The reduced diameter of the groove, often calculated based on the nominal diameter ( ) minus a specific value (e.g., for certain pitches).

(Undercut Width): The axial length of the groove. A common rule of thumb is that the undercut should be roughly times the thread pitch (

Transition Angle: The standard typically recommends a minimum transition angle of 30∘30 raised to the composed with power Sample Dimension Data Thread Pitch ( Undercut Diameter ( Data extracted from standard UNI ISO 4755 tables. Best Practices for Designers

Check Your Pitch: Dimensions for undercuts are strictly dependent on the thread pitch, not just the diameter.

Consult the Product Standard: UNI ISO 4755 is the general recommendation, but specific product standards (like those for specialized plugs) may take precedence.

Manufacturing Method: Be aware that rolled threads may have different requirements compared to machined (cut) threads, as noted in related standards like UNI 5709. ISO-4755-1983.pdf - iTeh Standards

1. Clarifying the Standard: ISO 4755

Many engineers search for ISO 4755 expecting a table of dimensions. However, ISO 4755 is a "design rules" standard, not a dimension table itself. It dictates how the groove should be designed to ensure the screw functions correctly.

The standard specifically covers:

Tapping Screws (Thread-forming and thread-cutting): Screws that create their own thread in the material.
Metal Drive Screws: Screws driven in with a hammer.

The "Gola" in this context usually refers to the V-notch or cutting flute found at the tip of the screw.

What is UNI ISO 4755? (A Quick Overview)

Before diving into the table (tabella), we must understand the standard itself. UNI ISO 4755 is the Italian adoption of the international standard ISO 4755. The title is: "Fasteners — Bolts, screws and studs with a thread length shorter than nominal length — Undercuts for metric threads according to ISO 261."

In simpler terms: When a bolt has a thread that does not run the entire length of the shank, the transition zone between the unthreaded shank (or the bolt head) and the threaded portion is called the gola. This standard specifies precise radii and diameters for that undercut to relieve stress and ensure proper tightening.

Importance of the UNI ISO 4755 Standard

The UNI ISO 4755 standard is crucial for several reasons:

Standardization: It ensures that there is a uniform method of presenting and interpreting data related to the Tabella Gola Uni. This uniformity is vital in industries where precision and consistency are paramount.
Quality and Safety: By adhering to this standard, manufacturers and engineers can ensure that their products or designs meet specific safety and quality criteria, reducing the risk of errors or failures.
International Compatibility: The alignment with ISO standards facilitates international trade and collaboration, as products and documents produced under this standard are easily understood and accepted globally.
Efficiency: Standardization streamlines processes, from design to production, by providing clear and universally accepted guidelines, thereby reducing the time and resources required for product development and certification.

2. Why the “Tabella Gola” is needed

Without a standardized undercut:

A threaded part cannot screw flush against a shoulder because the thread run-out leaves an incomplete thread profile.
Manufacturing (tapping, die-cutting, thread milling) would be less predictable.

The gola (undercut) provides a clearance groove with a controlled diameter and width, ensuring:

Full seating of mating parts.
Reliable thread depth up to the end of the part.
Reduced stress concentration.