Tabella Gola Uni Iso 4755 Here

| Standard | Region | Key Differences from UNI ISO 4755 | |----------|--------|------------------------------------| | DIN 76-1 | Germany | Slightly larger undercut widths for some diameters; includes trapezoidal threads. | | UNI 4749 (obsolete) | Italy | Had distinct values for fine vs. coarse; now replaced by ISO 4755. | | ANSI B18.3 | USA | Inch-based; uses a different undercut geometry for socket head cap screws. |

Important: When designing for global markets, prefer ISO 4755 unless a customer explicitly requests DIN 76-1.

🖼 Image Idea: A technical drawing zooming in on a threaded bolt, highlighting the "undercut" area with red arrows, plus a small cropped table.

Caption:

When the thread meets the shoulder, you need a Gola! 🔩

Searching for the "Tabella Gola UNI ISO 4755" ?

This standard defines the perfect undercut dimensions for ISO metric threads. It tells you exactly: 👉 How deep to cut 👉 How wide to make the relief

Example: For an M10 x 1.5 thread → Machine a groove Ø9.4 mm x 2.4 mm wide.

Save this post for your next CNC programming session! 📌

#UNIISO4755 #MechanicalEngineering #Threading #Gola #MachinistLife

The story of UNI ISO 4755 (often referred to in technical tables as the "Tabella Gola") is a tale of precision tucked away in the smallest of places: the thread undercut.

In the world of mechanical engineering, there is a recurring problem with bolts and screws. When you try to screw a bolt all the way into a flat surface, the threads often can't reach the very base of the head because of how the manufacturing tools work. Without a "gola" (the Italian word for "throat" or "groove"), the bolt won't sit flush against the surface. The Problem in the Workshop

Imagine a master machinist in 1980, struggling to seat a heavy-duty plug into a hydraulic manifold. Because the thread ended abruptly, a tiny ridge of metal prevented a perfect seal. This was a common headache until Technical Committee ISO/TC 2 stepped in to standardize the solution. The Birth of the Standard

In December 1981, the draft for what would become ISO 4755 began circulating among international member bodies. It was officially accepted in 1983 (and adopted as UNI ISO 4755 in Italy in 1986).

The "story" this standard tells is one of universal language. It dictates exactly how to carve a small groove at the end of an external metric thread so that:

The fastener sits flush: The undercut provides a "landing zone" for the tool, ensuring no stray metal interferes with the seating. tabella gola uni iso 4755

The stress is distributed: By standardizing the radius and depth of the groove, engineers can predict exactly how much load the bolt can handle without snapping at its weakest point. The "Tabella Gola" Today

Today, the Tabella Gola UNI ISO 4755 is the silent hero of assembly lines. It provides a simple lookup for dimensions like: : The diameter of the undercut. : The width and transition lengths of the groove.

Whenever you see a bolt that fits perfectly tight against a machine part, you are looking at the legacy of this 1980s standardization—a small groove that solved a massive industrial friction. ISO-4755-1983.pdf - iTeh Standards

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 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?

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 ( | Standard | Region | Key Differences from

). 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

It is vital to distinguish UNI ISO 4755 from similar standards:

Tip for buyers: If a supplier says "conforms to DIN 76-1," they also conform to UNI ISO 4755 for 95% of metric sizes. However, always verify the specific a dimension if you have a blind hole with a specific depth.

This standard defines the geometry of the tip of the screw/bolt. It ensures that the screw can be easily started into a hole without damaging the thread.

There are typically two types of ends defined:

The critical dimension defined in the table is the Chamfer Angle ($\alpha$) and the Minimum Chamfer Flat ($u$).

Visual Interpretation:

High-pressure systems require threaded studs that seat perfectly against a mating port. The UNI ISO 4755 groove ensures that the thread run-out does not interfere with the sealing face (like an O-ring boss or a 24-degree cone seal).

The following table extracts the mandatory dimensions for metric thread undercuts as defined by UNI ISO 4755. The table is organized by the nominal thread diameter (d) – specifically for coarse pitch threads (the most common standard).

Note: All values are in millimeters (mm).

| Thread Size (d) | Pitch (P) | Groove Diameter (d₁) max | Groove Width (a) nominal | Radius (r) max | | :--- | :--- | :--- | :--- | :--- | | M1.6 | 0.35 | 1.25 | 0.5 | 0.2 | | M2 | 0.40 | 1.60 | 0.5 | 0.2 | | M2.5 | 0.45 | 2.05 | 0.6 | 0.2 | | M3 | 0.50 | 2.50 | 0.8 | 0.2 | | M4 | 0.70 | 3.30 | 1.0 | 0.2 | | M5 | 0.80 | 4.10 | 1.2 | 0.3 | | M6 | 1.00 | 5.00 | 1.5 | 0.3 | | M8 | 1.25 | 6.80 | 2.0 | 0.4 | | M10 | 1.50 | 8.50 | 2.5 | 0.4 | | M12 | 1.75 | 10.20 | 3.0 | 0.6 | | M14 | 2.00 | 12.00 | 3.5 | 0.6 | | M16 | 2.00 | 14.00 | 4.0 | 0.6 | | M20 | 2.50 | 17.50 | 5.0 | 0.8 | | M24 | 3.00 | 21.00 | 6.0 | 1.0 | | M30 | 3.50 | 27.00 | 7.5 | 1.0 | | M36 | 4.00 | 33.00 | 9.0 | 1.2 | | M42 | 4.50 | 38.50 | 10.5 | 1.2 | | M48 | 5.00 | 44.00 | 12.0 | 1.6 | | M56 | 5.50 | 52.00 | 14.0 | 1.6 | | M64 | 6.00 | 59.00 | 16.0 | 2.0 |

The complete UNI ISO 4755:2005 (including the full tabella gola with all diameters from M1 to M100+) is available for purchase from:

⚠️ This report is for informational purposes only. For manufacturing, always refer to the official standard document.

If you need the exact numeric table for a specific thread size (e.g., M6, M10, M16), let me know and I can extract the corresponding gola dimensions according to UNI ISO 4755.

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 ( ) Important: When designing for global markets, prefer ISO

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)?

Tabella Gola Uni Iso 4755 Here

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