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FULLERKREG Grade 12.9 Fine Thread Black Socket Cap Screws are high-strength hexagon socket head cap screws manufactured from ML40Cr carbon steel with a black oxide surface treatment. The fine thread (pitch finer than standard coarse thread) provides superior resistance to vibration loosening, higher clamping force per unit torque, and more precise axial adjustment — making these screws the preferred choice for precision machinery, hydraulic systems, automotive, and aerospace-grade applications where standard coarse thread is insufficient.
Fine thread is a specialist choice. Understanding the differences helps you select the correct fastener for your application:
| Property | Fine Thread (This Page) | Coarse Thread (Standard) |
|---|---|---|
| Thread pitch | Smaller (e.g. M10×1.0 or M10×1.25) | Larger (e.g. M10×1.5) |
| Vibration resistance | Superior — less likely to self-loosen | Standard |
| Clamping force per torque | Higher — more efficient torque-to-clamp conversion | Standard |
| Axial adjustment precision | Finer — more precise positioning per turn | Coarser |
| Thread stripping resistance | Higher (more thread contact area) | Standard |
| Assembly speed | Slower (more turns required) | Faster |
| Cross-threading risk | Slightly higher | Lower |
| Availability | Specialist / made to order | Widely stocked |
| Typical applications | Precision machinery, hydraulics, automotive, aerospace | General industrial use |
The following fine thread pitches are available for DIN 912 / ISO 4762 Grade 12.9 socket cap screws. Fine thread designation format: M[diameter] × [pitch].
| Thread Size | Fine Pitch (p) | Coarse Pitch (ref.) | Head Dia. dk | Head Height k | Key Size s | Key Depth t Min. |
|---|---|---|---|---|---|---|
| M8 × 1.0 | 1.0 | 1.25 | 13.00 | 8.00 | 6 | 4.0 |
| M10 × 1.0 | 1.0 | 1.5 | 16.00 | 10.00 | 8 | 5.0 |
| M10 × 1.25 | 1.25 | 1.5 | 16.00 | 10.00 | 8 | 5.0 |
| M12 × 1.25 | 1.25 | 1.75 | 18.00 | 12.00 | 10 | 6.0 |
| M12 × 1.5 | 1.5 | 1.75 | 18.00 | 12.00 | 10 | 6.0 |
| M14 × 1.5 | 1.5 | 2.0 | 21.00 | 14.00 | 12 | 7.0 |
| M16 × 1.5 | 1.5 | 2.0 | 24.00 | 16.00 | 14 | 8.0 |
| M18 × 1.5 | 1.5 | 2.5 | 27.00 | 18.00 | 14 | 9.0 |
| M20 × 1.5 | 1.5 | 2.5 | 30.00 | 20.00 | 17 | 10.0 |
| M22 × 1.5 | 1.5 | 2.5 | 33.00 | 22.00 | 17 | 11.0 |
| M24 × 2.0 | 2.0 | 3.0 | 36.00 | 24.00 | 19 | 12.0 |
| M27 × 2.0 | 2.0 | 3.0 | 40.00 | 27.00 | 19 | 13.5 |
| M30 × 2.0 | 2.0 | 3.5 | 45.00 | 30.00 | 22 | 15.5 |
| M33 × 2.0 | 2.0 | 3.5 | 50.00 | 33.00 | 24 | 17.5 |
| M36 × 3.0 | 3.0 | 4.0 | 54.00 | 36.00 | 27 | 19.0 |
All values are maximum unless a range is indicated.
| Grade | C | Si | Mn | P (max) | S (max) | Cr |
|---|---|---|---|---|---|---|
| ML40Cr | 0.37–0.44 | 0.17–0.37 | 0.50–0.80 | ≤0.030 | ≤0.030 | 0.80–1.10 |
| Property | Requirement | Unit |
|---|---|---|
| Tensile Strength (Rm) | Min. 1,220 | MPa |
| Yield Strength / Proof Load Stress (Rp0.2) | Min. 1,100 | MPa |
| Core Hardness | 39–44 | HRC |
| Surface Hardness (max) | ≤50 | HRC |
| Elongation after fracture (A) | Min. 8 | % |
| Reduction of area (Z) | Min. 44 | % |
| Thread Tolerance Class | 6H/6g | — |
| Surface Treatment | Black oxide (blackening) | — |
FULLERKREG Grade 12.9 fine thread black socket cap screws are used in precision and high-vibration applications including:
⚠️ Fine thread socket cap screws require matching fine-threaded tapped holes or nuts. Standard coarse-thread tapped holes are not compatible. Please confirm your mating thread specification before ordering. Fine thread sizes and pitches must be specified at time of order (e.g. M16 × 1.5).
Q: How do I specify a fine thread socket cap screw?
Specify the thread diameter and pitch together, e.g. “M16 × 1.5” means 16mm diameter with 1.5mm pitch. Standard coarse M16 has a 2.0mm pitch. Always confirm the pitch of your tapped hole before ordering.
Q: Can fine thread screws be used in coarse-threaded holes?
No. Fine thread and coarse thread are not interchangeable. Using a fine thread screw in a coarse-threaded hole will result in cross-threading and damage to both the screw and the hole.
Q: Why is Grade 12.9 preferred for fine thread applications?
Fine thread applications typically involve high-precision, high-load joints where maximum clamping force is required. Grade 12.9 provides the highest standard tensile strength (1,220 MPa), making it the natural choice for demanding fine thread applications.
Q: Are these screws available in custom lengths?
Yes. Custom lengths are available for large orders. Please contact our sales team with your specific requirements.
Q: Can I get material certificates and test reports?
Yes. PPAP reports, material certificates, hardness test reports, tensile test reports, and thread gauge inspection reports are available upon request.
All FULLERKREG Grade 12.9 fine thread black socket cap screws are manufactured under strict quality control procedures including:
For wholesale pricing, bulk orders, custom fine thread specifications, or technical inquiries, please contact our sales team.
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