Release time：2020-01-16 18:44 Browse：
### 1. **Strength Classification & Mechanical Properties** - **Grade 8.8**: A medium-high strength bolt grade, defined by ISO 898-1 standards. Tensile strength reaches ≥800MPa, with a yield strength of ≥640MPa (yield ratio 0.8). - **Material & Heat Treatment**: Typically made from medium-carbon steel (e.g., 45# steel) or alloy steel, hardened and tempered to achieve optimal strength and toughness—resistant to deformation under heavy loads. ### 2. **Design & Structural Details** - **Hex Flange Head**: Hexagonal driving surface (compatible with standard hex wrenches/sockets) paired with an integrated flange (a circular, flat extension from the head). - **Built-in Washer Function**: The flange acts as a washer, increasing the contact area with the workpiece to distribute clamping force, reduce surface pressure, and prevent damage to soft materials (e.g., wood, plastic). - **Thread Specification**: Available in metric (e.g., M6, M8) or imperial sizes, with coarse or fine threads to suit different thicknesses of connected parts. ### 3. **Surface Finish: Zinc Plating** - **Coating Process**: Electroplated zinc layer (typically 5-20μm thick) forms a protective barrier against oxidation, enhancing corrosion resistance in dry/indoor environments. - **Appearance & Function**: Silver-gray, shiny finish; may include a clear passivation layer (chromate treatment) to improve zinc adhesion and extend rust resistance. ### 4. **Functional Advantages** - **Integrated Design**: Eliminates the need for separate washers, streamlining assembly processes and reducing part counts in production. - **Vibration Resistance**: The flange’s large contact area and uniform clamping force help prevent loosening in dynamic applications (e.g., machinery, automotive engines). - **Cost-Effective Strength**: Grade 8.8 offers a balance of high strength and affordability, suitable for non-extreme load scenarios (stronger than 4.8 grade, more economical than 10.9 grade). ### 5. **Typical Applications** - **Industrial Machinery**: Securing gearboxes, motor mounts, conveyor frames, and structural brackets. - **Automotive Assembly**: Chassis components, suspension parts, and under-hood fasteners (where moderate strength and corrosion resistance are needed). - **Construction & Furniture**: Fastening metal frames, steel structures, and heavy-duty furniture (blending strength with ease of installation). ### 6. **Installation & Compatibility** - **Driving Tools**: Works with standard hex keys, socket wrenches, or power tools (impact drivers) for efficient tightening. - **Torque Requirements**: Follows grade-specific torque guidelines to avoid over-tightening (which may strip threads) or under-tightening (which risks loosening). - **Limitations**: Zinc plating is less corrosion-resistant than stainless steel, so not ideal for high-moisture or salt-exposed environments (e.g., marine, outdoor use).
