Product Summary

Longze High-Strength Hex Flange Bolts are high-performance fasteners featuring an integrated circular flange under the head, effectively replacing the need for a separate flat

washer. Manufactured in Yongnian, China, our flange bolts are engineered for high-vibration environments, providing superior load distribution and preventing embedment into the

base material. Whether for automotive chassis assembly or heavy industrial gearboxes, Longze flange bolts offer the structural integrity and clamping force required for critical joints.

• ✔ Integrated Washer Design: The wide-bearing flange surface distributes the clamping load over a larger area, reducing surface pressure on the fastened part.

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• ✔ Anti-Loosening Performance: Available in both smooth and serrated flange options to increase friction and resist self-loosening under cyclic vibration.

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• ✔ High-Tensile Reliability: Precision-forged from alloy steel and quenched/tempered to meet Class 10.9 and 12.9 mechanical requirements.

• Standards: DIN 6921, ISO 4162, EN 1665, ASME B18.2.1.

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• Diameter Range: M5 to M24 | 1/4" to 1".

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• Length Range: 10mm to 200mm (Custom lengths for heavy machinery).

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• Material Grade: Carbon Steel (Class 8.8, 10.9, 12.9) | Stainless Steel 304 & 316.

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• Surface Finish: Black Oxide, Zinc Plated (Blue/White/Yellow), Dacromet, Geomet, Zinc-Nickel.

Mechanical Properties & Material Standards

• Matching the steel grade to the structural requirements of the transmission line.

• Property Class	재료	Tensile Strength (min)	Yield Strength (min)	Hardness Range
  Class 8.8	Medium Carbon Steel	800 MPa	640 MPa	22 - 32 HRC
  Class 10.9	합금강	1040 MPa	940 MPa	32 - 39 HRC
  Class 12.9	합금강	1220 MPa	1100 MPa	39 - 44 HRC
  Stainless 316	A4-80	800 MPa	600 MPa	240 - 320 HV

Standard Cross Arm Dimensions

• Common angle steel configurations for standard utility pole mounting.

• Thread Size (D)	Flange Dia (dc)	Head Height (k)	Width Across Flats (s)	Pitch (Metric)
  M8	18 mm	8.1 mm	13 mm	1.25 mm
  M10	22.3 mm	9.2 mm	15 mm	1.5 mm
  M12	26.6 mm	11.5 mm	18 mm	1.75 mm
  M16	35 mm	14.4 mm	24 mm	2.0 mm

Avoid Pitfalls:

• Hydrogen Embrittlement (High Grade): For Class 10.9 and 12.9 bolts, we perform a strict 4-8 hour de-embrittlement baking process immediately after electroplating to prevent sudden brittle fracture.

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• Flange Eccentricity: We utilize high-speed multi-station cold heading machines to ensure the hex head is perfectly centered on the flange, preventing uneven torque and tool slippage.

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• Inconsistent Friction: Surface coatings (like Dacromet) significantly alter the torque-to-tension relationship. Longze provides friction coefficient reports to ensure your automated assembly lines run with 100% accuracy.

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Perfect Fit Assembly:

• Serrated vs. Smooth: 사용 Serrated Flange Bolts for vibration-heavy applications (like engine mounts) and Smooth Flange Bolts for delicate surfaces that must not be scratched.

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• Matched Flange Nuts: Pair these with our DIN 6923 Flange Nuts to create a unified, washer-free fastening system that reduces assembly time by up to 30%.

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Quality Control & Logistics:

• ISO 9001 Certified: 5-step QC including computerized sorting for dimension consistency, torque-tension testing, and microstructure analysis of the heat-treated alloy.

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• Sea-Worthy Packaging: Bolts are packed in heavy-duty 25kg cartons with plastic-lined moisture protection, shipped on reinforced Fumigation-Free Pallets from our Yongnian hub.

• Q: Can you provide fine-pitch flange bolts for automotive engines? A: Yes, we specialize in fine-pitch options (e.g., M10x1.25, M12x1.25) in Grade 10.9, widely used in the automotive and motorcycle industries.

• Q: What is the benefit of the flange over a separate bolt and washer? A: The flange is integrated, meaning it cannot be forgotten during assembly, it provides a larger bearing surface, and it streamlines inventory management.