In industrial assembly scenarios where efficiency and reliability are critical, the Hex Socket Screw with Flat and Spring Washer Assembly offers an integrated, pre-assembled solution that meets strict Chinese GB standards. Covering M3–M8 threads, this assembly combines a PH cross recess hex socket screw with a flat washer and spring washer into a single unit, reducing assembly time by over 60% and minimizing errors such as missing, reversed, or misaligned washers.
The assembly is suitable for both manual and automated assembly, even in high, narrow, or hard-to-reach locations. Optimized stress distribution in the recessed hex head prevents head breakage or stripping, while the hex geometry enables high torque transfer.
Material & Performance:
- Carbon Steel Version: 10B21 bolt (≥4.8 grade tensile strength), 65Mn spring washer, heat-treated, elastic recovery ≥90%, ideal for high-strength structural connections.
- Stainless Steel Version: SUS304 full set, Cr≥18%, Ni≥8%, corrosion resistance ≥48h neutral salt spray, ideal for moisture, outdoor, and mildly corrosive environments.
- Hardness: Bolt HRC 22–28, spring washer HRC 42–48, flat washer HRC 18–25.
Applications:
- 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.
The assembly ensures pre-tightening compensation against vibration and shock, maintains surface protection via 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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