Where are fine thread nut typically used?
Fine-pitch nuts, characterized by their small thread pitch, high fastening precision, and strong anti-loosening performance, are primarily used in applications requiring high connection stability, precise adjustment, or vibration resistance.
Fine nut are classified according to their application scenarios.
| Application Scenarios | Core requirements | Recommended specifications (nominal diameter × pitch) | Strength grade | Material | Surface treatment | standard | Remark |
| Precision machinery (machine tools / instruments) | Precision adjustment, low damage. | M3×0.35、M4×0.5、M5×0.5、M6×0.75、M10×1.0 | Grade 8 (800 MPa) | 304 stainless steel / alloy steel | Nickel plating / Blackening | ISO 4035、DIN 934 | Suitable for thin-walled components; using threadlocker adhesive is recommended for better results. |
| Automotive industry (engines / chassis) | Vibration-resistant and anti-loosening, high strength | M8×1.0、M10×1.25、M12×1.5、M14×1.5 | grade 8 / 10 | Medium carbon steel / 42CrMo | Dacromet / Hot-dip galvanizing | DIN 934、GB/T 6175 | Use grade 10 for the engine and grade 8 for the transmission. |
| Aerospace (airframe / landing gear) | Lightweight and highly reliable. | M6×0.75、M10×1.0、M16×1.5 | grade 10 / 12 | Titanium alloy / 316L stainless steel | ISO 4036, NAS standards | Hydrogen embrittlement testing is required. | |
| Electrical Power (Electric Motors / Wind Power) | Outdoor weather-resistant, vibration-resistant | M12×1.5, M16×1.5, M20×2.0 | Grade 8, 304/316 Stainless Steel | Dacromet / Hot-dip galvanized | DIN 439, GB/T 6176 | Grade 10 for wind power applications + anti-loosening washer | |
| Medical Devices (Surgical Instruments / Diagnostic Equipment) | Low Torque, Corrosion Resistant | M2×0.25, M3×0.35, M4×0.5 | Grade 6 / Grade 8 | Titanium Alloy / 316L Stainless Steel | Passivation / Electropolishing | GB 808 | Avoid damaging precision components |
| Rail Transit (Bogie / Car Body) | Vibration-resistant, High and low temperature resistant | M12×1.5, M16×1.5, M20×2.0 | Grade 8 / Grade 10 | Medium carbon steel / Alloy steel | Dacromet / Zinc plating | DIN 934 | Grade 10 for bogies + Hydraulic pre-tensioning |
| Molds / Fixtures | Precise positioning, fine adjustment | M5×0.5, M6×0.75, M8×1.0 | Grade 8 45# Steel / Stainless Steel | Black oxide finish / Nickel plating | GB/T 6172 | Fine-pitch screws for gap adjustment |
Explanation of key selection parameters
Specification Matching Principle:
Prioritize selecting fine nut of the same size as the corresponding bolts (e.g., M10 bolts should be paired with M10×1.0/M10×1.25 fine-pitch nuts). Mismatched thread pitches will lead to stripping or inability to assemble.
For limited space, choose thin-type nuts (e.g., ISO 4036 hexagonal thin nuts); for general use, use the standard ISO 4035 type.
Strength Grade Selection
Grade 6 (≥600MPa): Light load (electronic equipment, small instruments).
Grade 8 (≥800MPa): General heavy load (automobile chassis, electric motors).
Grade 10 / Grade 12 (≥1000MPa): High stress (aerospace, engines, high-speed rail bogies).
Material and Surface Treatment Key Points:
Corrosive environments (outdoor/chemical): 304/316 stainless steel + passivation/Dacromet coating.
High-temperature conditions (engines/boilers): Alloy steel + nickel plating/nitriding.
Food/medical applications: Titanium alloy/316L + electrolytic polishing, no harmful substances released.
Anti-loosening and Assembly Recommendations:.
For vibrating conditions: Use all-metal self-locking nuts (DIN 985), or add lock washers + apply thread locker adhesive.
For precise adjustment: Use fine-pitch double nuts for anti-loosening, and perform secondary tightening after fine-tuning.