Pre-Assembled Hex Bolt with Flat and Spring Washers
This pre-assembled hex bolt comes with flat and spring washers, designed for heavy-duty fastening in industrial manufacturing, construction, and heavy equipment. It is available in M3–M12, combining a hex bolt, flat washer, and spring washer into a single unit. As a result, it eliminates misplacement, misalignment, or omission during assembly.
Key Features
- High Torque Capability: The optimized hex head design supports wrenches and sockets, ensuring secure fastening in high-strength applications.
- Material Options: Choose between carbon steel 8.8-grade (tensile strength ≥800MPa) or SUS304/SUS316 stainless steel for enhanced corrosion resistance.
- Washer Functionality: Flat washers evenly distribute load, while spring washers maintain pre-tension and resist vibration.
- Precision & Assembly: Pre-assembled with tight coaxiality (≤0.1mm) to enable efficient torque transfer and a stable connection.
- Surface Treatment: Options include zinc plating, blackening, or passivation; salt spray resistance is ≥48 hours.
- Global Compliance: Fully RoHS certified, suitable for industrial, automotive, marine, and construction applications worldwide.
Applications
This fastening solution works perfectly for steel structures, mechanical frames, machinery, automotive chassis, marine equipment, and other heavy-load assembly scenarios. In addition, it simplifies installation and improves overall assembly efficiency.
| Parameter | Specification / Range | Notes |
|---|---|---|
| Standards | ISO 225 / EN15048-1:2016 | International and export compliance |
| Component Structure | 1 Hex Bolt + 1 Flat Washer + 1 Spring Washer | Pre-assembled unit |
| Thread Size | M3 – M12 | Metric coarse thread; M3:1.0mm, M4:1.4mm, M5:1.6mm, M6:2.0mm, M8:2.5mm, M10:3.0mm, M12:3.5mm |
| Thread Accuracy | 6g/6H | Pitch deviation ≤±0.02mm; flank angle ≤±1° |
| Bolt Length | 5 – 90mm | M3 min 5mm, M12 max 90mm |
| Head Width Tolerance | ±0.2mm | Across flats |
| Shank Straightness | ≤0.1mm/m | Ensures assembly alignment |
| Material – Carbon Steel | 35 / 45 Steel, Grade 8.8 | Yield ≥640MPa, Tensile ≥800MPa, Elongation ≥12%, Brinell Hardness 250–331HB |
| Material – Stainless Steel | SUS304, Grade 70 | Cr≥18%, Ni≥8%, C≤0.08%, corrosion-resistant |
| Flat Washer | Stamped steel, smooth edges | Distributes load, protects surface |
| Spring Washer | 65Mn spring steel | Elastic recovery ≥92%, resists vibration |
| Coaxiality | ≤0.1mm | Bolt and washers aligned |
| Torque Capacity | ≤120% of standard torque | e.g., M10 ≤120N·m |
| Surface Treatment Options | Zinc plating / Blue-white zinc / Hot-dip galvanizing / Black / Nickel plating / Passivation | Salt spray resistance ≥48–96h depending on treatment |
| Compliance | RoHS | Meets environmental & export requirements |
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