offset head bolt eccentric head bolt misaligned head bolt angled head bolt

Prioritize tapping for mass production, standard parts, through holes, low cost and high speed. Prioritize thread milling for deep blind holes, difficult-to-machine materials (e.g., titanium alloy, stainless steel), non-standard threads, mixed production of multiple specifications, and high precision requirements.

Grade 4.8: Low carbon steel, tensile strength ≥400MPa, yield strength ≥320MPa, for general light-load and non-critical connections. Grade 8.8: Medium carbon steel quenched and tempered, tensile strength ≥800MPa, yield strength ≥640MPa, for general heavy-load and main equipment. Grade 12.9: Alloy steel, tensile strength ≥1200MPa, yield strength ≥1080MPa, for high-strength, vibration/impact conditions (e.g., construction machinery, automotive chassis).

Spring washers (GB/T 93): Elastic preload, general light vibration, low cost. Lock washers (internal/external teeth, GB/T 861/862): Teeth embedment, stronger anti-loosening, suitable for medium to high strength. Thread adhesives (anaerobic adhesives): Permanent/semi-permanent locking, sealing and rust prevention, suitable for critical connections that are not frequently disassembled.

6g: Commonly used for external threads (bolts/screws), medium precision, general assembly. 6H: Commonly used for internal threads (nuts), medium precision, matches 6g external threads. 5g6g: High-precision combination for external threads (pitch diameter 5g, major diameter 6g), used in scenarios with high precision and anti-loosening requirements.

Format: Type + Standard No. + Specification + Surface Treatment. Example: Bolt BOLT-GB5783-M10×30-8.8-Zn; Nut NUT-GB6170-M10-8H-Zn; Washer WASHER-GB97.1-10-A-Zn. Must include: standard number, specification, strength/precision, surface treatment to ensure consistency in procurement and assembly.

Cut threads: Cut material fibers, grain fracture, poor fatigue resistance. Rolled threads: Cold work hardening + continuous fibers, grains distributed along thread flow lines, tensile/shear/fatigue resistance increased by 30%–100%, especially suitable for high-strength standard fasteners.