In industrial assembly scenarios where efficiency and reliability are critical, the Hex Socket Screw with Flat and Spring Washer Assembly provides an integrated, pre-assembled solution that meets strict Chinese GB standards. Covering M3–M8 threads, Shenhu combines a PH cross recess hex socket screw with a flat washer and a spring washer into a single unit. This design reduces assembly time by over 60% and minimizes errors such as missing, reversed, or misaligned washers.
Suitable for Manual and Automated Assembly
The assembly accommodates both manual and automated processes, even in high, narrow, or hard-to-reach locations. Additionally, the optimized stress distribution in the recessed hex head prevents head breakage or stripping. The hex geometry also enables efficient torque transfer, ensuring reliable fastening in demanding conditions.
Material & Performance
Carbon Steel Version
Shenhu uses 10B21 bolts with ≥4.8 grade tensile strength and 65Mn spring washers. These components undergo heat treatment and provide elastic recovery ≥90%, making them ideal for high-strength structural connections.
Stainless Steel Version
The SUS304 full set, with Cr≥18% and Ni≥8%, delivers corrosion resistance ≥48h in neutral salt spray, making it suitable for moisture-prone, outdoor, and mildly corrosive environments.
Hardness Specifications
- Bolt: HRC 22–28
- Spring Washer: HRC 42–48
- Flat Washer: HRC 18–25
Together, these properties provide vibration resistance and maintain secure fastening throughout long-term operation.
Applications Across Industries
This pre-assembled solution is widely used in multiple industries:
- Electronics: Control cabinets, motors, air conditioning units
- Automotive & Transportation: Seats, hinges, frames
- Outdoor & Construction: Solar mounts, guardrails, electrical boxes
- Machinery & Agricultural Equipment: Pumps, compressors, harvesters
Consequently, it ensures pre-tightening compensation against vibration and shock, protects surfaces with large flat washers, and provides standardized, reliable fastening for high-volume production.
| Parameter | Specification |
|---|---|
| Standards | GB9074.13-88; compatible with GB 29.2, GB 944.1, GB 9074.26; reference ISO 8676, ISO 7091 |
| Thread Range | M3–M8, coarse thread |
| Thread Pitch | M3: 0.5mm; M4: 0.7mm; M5: 0.8mm; M6: 1.0mm; M8: 1.25mm |
| Bolt Length | 6–50mm, 5mm increments |
| Thread Length | Half-thread: M3–M5 ≥1/2 bolt length; M6–M8 ≥2/3 bolt length |
| Materials | Carbon Steel 10B21; SUS304 Stainless Steel |
| Washer Materials | Flat washer: carbon steel/SUS304; Spring washer: 65Mn steel (heat-treated) |
| Tensile Strength | Carbon steel ≥4.8 grade; Stainless steel SUS304 ≥700MPa |
| Bolt Head | PH cross recessed hex head, hex width: M3 5.5mm, M4 7mm, M5 8mm, M6 10mm, M8 13mm; PH2 cross recess, depth 2–3.5mm |
| Flat Washer | Outer diameter 2.2–2.5× bolt diameter, thickness 0.8–1.5mm |
| Spring Washer | Open type, free height 2.5–3× thickness, compression ≤30% no permanent deformation |
| Pre-assembly Fixing | Riveted, axial pull ≥50N, washer fixed |
| Thread Tolerance | 6g, pitch angle deviation ≤±3° |
| Surface Treatment | Carbon steel: zinc-plated (8–12µm) / nickel-plated (5–8µm); SUS304: passivated (5–10µm) |
| Corrosion Resistance | Salt spray: ≥48h for zinc-plated or SUS304 |
| Weight Range | M3×6: 0.8g; M8×50: 18.5g |
| Packaging | 100 pcs/box, 500 pcs/box, or customized with English labels and standard markings |
| Certifications | RoHS; Carbon steel: GB/T 3098.1; Stainless steel: GB/T 3098.6 |
| Applications | Electronics, automotive, machinery, construction, outdoor equipment |
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