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When a standard coarse-thread bolt just won't hold under vibration, or when you're threading into aluminum and can't afford a stripped hole, fine thread socket cap screws are the professional's choice. Machinists, automotive technicians, and mechanical engineers rely on these fasteners for engine assemblies, gearbox covers, suspension components, and precision fixtures where every thread counts.
Each screw features a cylindrical cap head with a hex socket (Allen) drive, machined to DIN 912 / ISO 4762 standards. Available in diameters from M6 to M20 with fine thread pitches — M6×0.75, M8×1.0, M10×1.0, M10×1.25, M12×1.25, M12×1.5, M14×1.5, M16×1.5, M18×1.5, and M20×1.5 — and lengths ranging from 10mm (≈3/8") to 100mm (≈3-15/16"). Sold individually (1 pc) or in packs of 5 for project quantities.
Typical use cases include automotive engine and transmission work requiring fine thread socket head cap screws, CNC machine tool assembly with metric hex socket bolts, and industrial equipment maintenance where vibration-resistant fasteners are specified. The fine pitch thread also makes these ideal as replacement bolts for European and Japanese machinery.
| Drive Type | Hex Socket (Allen / Internal Hex) |
|---|---|
| Head Style | Cylindrical Cap Head (Socket Cap) |
| Thread Standard | Metric Fine Thread (MF) — DIN 912 / ISO 4762 |
| Available Diameters | M6, M8, M10, M12, M14, M16, M18, M20 |
| Thread Pitches | M6×0.75 / M8×1.0 / M10×1.0 & 1.25 / M12×1.25 & 1.5 / M14×1.5 / M16×1.5 / M18×1.5 / M20×1.5 |
| Available Lengths | 10mm (≈3/8") to 100mm (≈3-15/16") — see variant options |
| Material | Alloy Steel (typically Grade 12.9 equivalent — contact us to confirm) |
| Surface Finish | See variant options |
| Hex Key Size Required | See variant options (M6=5mm, M8=6mm, M10=8mm, M12=10mm, M14=12mm, M16=14mm, M18=14mm, M20=17mm — typically) |
| Pack Quantity | 1 pc or 5 pcs (select Amount above) |
| Country of Origin | Contact us to confirm |
Measure the depth of the threaded hole or the thickness of the material being clamped. For through-bolting, the screw length should generally equal the material thickness plus at least 1.5× the thread diameter for engagement. For example, an M8 bolt threading into 20mm of material typically needs a length of 30–35mm (≈1.2–1.4"). When in doubt, size up — you can always use a washer to adjust stack height.
Load capacity depends on diameter, grade, and material. These screws are generally made from alloy steel and are typically rated to Grade 12.9 equivalent tensile strength — among the highest available for metric fasteners. For precise proof load and tensile load values for your specific size, contact us to confirm before use in safety-critical applications.
These socket cap screws are generally alloy steel without a dedicated corrosion-resistant coating. For outdoor, marine, or high-humidity environments, we recommend applying anti-seize compound or selecting stainless steel alternatives. Contact us to confirm the surface finish of your specific variant before use in exposed conditions.
These screws use metric fine thread (MF) per ISO 262 / DIN 912. Fine thread pitches (e.g., M10×1.0, M12×1.25) provide greater resistance to loosening under vibration compared to coarse thread. Always verify the thread pitch of your mating nut or tapped hole before ordering — fine thread and coarse thread are not interchangeable even at the same diameter.
Standard DIN 912 hex key sizes are typically: M6 → 5mm, M8 → 6mm, M10 → 8mm, M12 → 10mm, M14 → 12mm, M16 → 14mm, M18 → 14mm, M20 → 17mm. Most metric Allen key sets cover this full range. A torque wrench with a hex bit is recommended for critical assemblies.
Yes — socket cap screws are commonly used in aluminum housings, engine components, and soft-metal assemblies. Fine thread pitches are particularly advantageous in aluminum because they distribute clamping load over more thread engagement, reducing the risk of stripping. Use appropriate torque values and consider thread inserts (e.g., Helicoils) for high-cycle or high-load applications.
Fine thread screws have a smaller pitch (more threads per unit length), which provides better resistance to vibration loosening, finer torque adjustment, and stronger thread engagement in thin materials. Coarse thread is faster to assemble and more tolerant of minor thread damage. Fine thread is generally preferred in automotive, aerospace, and precision machinery where vibration and tight tolerances are critical.
We currently offer 1-piece and 5-piece quantities for most sizes. For larger project quantities or custom length requirements, contact us directly — we are happy to discuss volume pricing and sourcing options for your specific application.
