Product Summary

Longze Hexagonal Flange Self-Tapping Screws (commonly known as Sheet Metal Screws or Flange Tappers) are high-efficiency fasteners manufactured to DIN 6928, ISO 1479, en ASME B18.6.3 standards.

These Longze Hexagonal Flange Self-Tapping Screws feature an integrated circular flange head and sharp, hardened threads designed to cut their own mating threads in pre-drilled holes. They provide a

high-clamping force and a large bearing surface, making them the primary choice for securing thin metal sheets, HVAC ducting, and automotive panels.

• ✔ Integrated Washer Design: The built-in flange eliminates the need for separate flat washers, distributing load evenly and preventing the screw head from pulling through thin materials.

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• ✔ High-Torque Hex Drive: The external hexagonal head allows for maximum torque application with power drivers, ensuring a secure and rapid installation in industrial assembly lines.

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• ✔ Self-Thread Forming: Precision-engineered sharp threads create a tight, vibration-resistant fit by forming a custom thread path in metal, plastic, or wood substrates.

Product Highlight: Engineered for high-torque applications, Longze flange self-tapping screws provide a high-strength, superior alternative to standard screws in heavy-duty sheet metal environments.

 

• Case-Hardened Steel – Heat-treated to a high surface hardness, ensuring the threads can successfully cut through structural steel and aluminum without deforming.

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• Leak-Resistant Sealing – The wide flange provides an excellent surface for adding EPDM bonded washers if a water-tight seal is required for roofing or outdoor enclosures.

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• Stable Power Driving – The hex head geometry provides a more stable connection to the driver bit than Phillips or Slotted drives, reducing "cam-out" and worker fatigue.

Technical Standard: Manufactured to strict international tolerances, ensuring 100% compatibility with standard driver bits and pre-drilled holes across all property classes.

 

• Standards: DIN 6928, ISO 1479 (Metric) / ASME B18.6.3 (Inch)

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• Thread Types: Type AB (Pointed), Type B (Blunt), Type A

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• Metric Size Range: ST2.9 to ST9.5

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• Inch Size Range: #4 to 3/8"

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• Material: Case-Hardened Carbon Steel / Stainless Steel 304, 316

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• Finish: Zinc Plated (Clear/Yellow), Black Oxide, Ruspert, Dacromet

Material & Mechanical Properties

• Engineering Note: Structural integrity depends on the correct property class. We offer a full material range to meet your specific tensile strength and ductility requirements.

• Materiaal	Hardness (Surface)	Core Hardness	Toepassing
  Carbon Steel	HV 450 min	HV 270 - 390	Automotive / HVAC / Appliances
  Vlekvrye staal	A2 (304)	Work Hardened	Solar Racks / Coastal Enclosures
  Vlekvrye staal	A4 (316)	Work Hardened	Marine / Chemical / Food Grade
  Alloy Steel	HV 550 min	HV 350 - 450	Heavy Industrial / High Sheer

Dimensions & Size Conversion

• Metric to Inch Comparison: Longze supports both Metric (DIN/ISO) and Imperial (ASME) standards. Use the table below to find the closest equivalent for your project requirements.

• Metric Size (ST)	Diameter (mm)	Nearest Inch Size	Diameter (inch)	Flange Dia (dc)
  ST2.9	2.9 mm	#4	0.112"	6.3 mm
  ST3.5	3.5 mm	#6	0.138"	8.3 mm
  ST4.2	4.2 mm	#8	0.164"	9.8 mm
  ST4.8	4.8 mm	#10	0.190"	10.5 mm
  ST5.5	5.5 mm	#12	0.216"	11.8 mm
  ST6.3	6.3 mm	1/4"	0.250"	13.2 mm

Surface Treatment

• Procurement Guide: Surface finish determines service life. Longze provides specialized coatings to ensure maximum corrosion resistance and aesthetic consistency for any environment.

• Coating	Salt Spray	Toepassing	Omgewing
  Zinc Plated	72 - 144h	Internal Panels	Indoor / Dry
  Yellow Zinc	96 - 168h	Industrial Frames	Humidity / Machinery
  Ruspert	500 - 1000h	Steel Roofing	Outdoor / Construction
  Passivated	1000h+	Marine / Medical	High Moisture (SS)