Tabella Gola Uni Iso 4755

Header: 🔧 Technical Deep Dive: Understanding the UNI ISO 4755 “Gola” (Thread Undercut)

Body: For designers and CNC programmers working with metric threads, precision at the root of the thread is critical. This is where UNI ISO 4755 comes into play.

Often referred to as the "Tabella Gola" (Undercut Table), this standard specifies the dimensions for thread run-outs and undercuts for ISO metric screw threads (M profile).

Why is this important? ✅ Stress Relief: Prevents stress concentration at the end of the threaded portion. ✅ Assembly: Ensures the mating part (nut or shoulder) seats perfectly against the abutment. ✅ Grinding: Provides the necessary space for thread grinding wheels to exit.

Quick Reference (Key Data from the table): The standard defines three types of undercuts (F, G, and variants) based on the thread pitch (p). For example:

⚠️ Always consult the full ISO/UNI table before finalizing critical components. tabella gola uni iso 4755

Do you design with standard undercuts, or do you customize your thread run-outs? Let me know below. 👇

#Engineering #ISO4755 #Threading #MechanicalDesign #UNIStandard #Manufacturing

If you are a machinist turning bolts on a lathe, the "gola" is programmed into the threading cycle. Before the chasing tool cuts the thread, a grooving tool creates the undercut to the dimensions above. Using the wrong width (a) will cause the threading tool to crash or leave a sharp step.

Reality: Intuitively, removing material seems weakening. However, by eliminating a sharp corner, the groove increases fatigue resistance. A bolt with an ISO 4755 undercut will last longer under dynamic loads (vibration, rotating bending) than a bolt with a sharp 90-degree transition.

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. Header: 🔧 Technical Deep Dive: Understanding the UNI

The standard specifically covers:

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

If you are designing a part or checking a measurement:

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

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). ⚠️ Always consult the full ISO/UNI table before

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 |

UNI ISO 4755 is the Italian adoption of the international standard ISO 4755:1983 – Fasteners – Bolts, screws and studs – Undercuts for metric threads. It replaces older national standards (e.g., UNI 4749) and aligns with modern ISO thread systems (e.g., ISO 68-1, ISO 261, ISO 965).

The standard specifies: