Flat Flange Nuts

Flat flange nuts are advanced fasteners that combine a standard hex nut with an integrated, wide, flat bearing flange. Their key advantage is the large, flat contact surface, which ensures even pressure distribution and prevents displacement. Manufactured to ISO 4161 standards, the flange surface is precision-ground to a flatness tolerance of ≤0.02 mm. This design increases the contact area with the base material by over 50% compared to a standard nut, effectively distributing clamping pressure and preventing deformation or damage to soft or thin materials. The hex body provides precise across-flats dimensions for easy wrenching, and the 6H-grade internal thread ensures secure engagement. Product is the premium choice for applications requiring broad surface pressure distribution.

Flat flange nuts are widely used in thin sheet fastening, automotive chassis, steel structure connections, appliance housings, and architectural hardware. When fastening thin sheets or panels, they distribute pressure to avoid unsightly dimpling or warping. In automotive chassis applications, they are paired with flange bolts to secure suspension and brake system components, with the large contact area ensuring stability under dynamic loads. For steel structures involving thin steel plate connections, they enhance load-bearing stability. In appliance manufacturing, they fasten housings to internal frames without causing dents. Product is the preferred choice wherever protecting the material surface is as important as joint strength.

These nuts are available in carbon steel Q235, stainless steel 304/316, or alloy steel 40Cr. Carbon steel meets the 4.8 strength grade for general use. Stainless steel variants offer excellent corrosion and weather resistance for outdoor or humid environments. Alloy steel 40Cr provides an 8.8 strength grade for higher load requirements. Surface treatments include zinc plating (ASTM B633), color zinc plating, and passivation (stainless steel), providing 72–120 hours of salt spray resistance. Flat flange nuts are ISO 9001 certified, and their flange load-bearing capacity conforms to ISO 4161. Customization is available for oversized flange diameters, thickened flanges, special thread specifications, and specialized surface treatments such as Dacromet or phosphating. Supplied in packs of 200–500 pieces per specification and including bolt selection guides, they facilitate precise matching for your projects.