Product Summary

Longo Hexagon Countersunk Head Screws are precision-manufactured according to DIN 7991 e ISO 10642 standards, serving as the premier choice for precision machinery, aerospace, automotive, and

interior design. Featuring a flat countersunk head, these Longo Hexagon Countersunk Head Screws allow the fastener to sit flush with or below the surface of the material, providing a smooth, snag-free finish and

high-torque internal hex drive performance.

• ✔ Flush Surface Finish: Designed with a 90-degree countersink angle, these Hexagon Countersunk Head Screws ensure a clean, professional aesthetic for visible assemblies.

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• ✔ High Torque Transfer: The internal hexagon (Allen) socket allows for higher tightening torques compared to traditional Phillips or slotted drives, reducing the risk of cam-out.

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• ✔ Industrial Strength: Longo offers high-tensile Alloy Steel options (Grade 10.9 and 12.9) for heavy-load applications where safety and durability are critical.

Key Features of Hexagon Countersunk Head Screws

• Space-Saving Design – The flat head eliminates protrusions, making it ideal for moving parts or tight-clearance applications.

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• Precision Internal Hex Drive – Ensures positive engagement with Allen keys or power bits for rapid, high-torque installation.

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• Wide Material Selection – From corrosion-resistant Aço inoxidável to ultra-high-strength Alloy Steel.

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• Standardized Accuracy – Fully compliant with Metric (DIN/ISO) and Imperial (ASME) countersink specifications.

Technical Specifications

• Standards: DIN 7991 / ISO 10642 / ASME B18.3

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• Size Range: M3 to M24 | #4 to 1" Inch sizes available

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• Property Class: Grade 10.9, 12.9 / A2-70, A4-80

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• Thread Type: Metric (Coarse/Fine), UNC, UNF

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• Finish: Black Oxide, Zinc Plated, Dacromet, Plain (Oiled)

• Material & Mechanical Properties

• Material	Grade / Type	Tensile Strength	Yield Strength	Hardness
  Alloy Steel	Grade 10.9	$\ge 1040$ MPa	$\ge 940$ MPa	32–39 HRC
  Alloy Steel	Grade 12.9	$\ge 1220$ MPa	$\ge 1100$ MPa	39–44 HRC
  Aço inoxidável	SS304 (A2)	$\ge 700$ MPa	$\ge 450$ MPa	140–200 HV
  Aço inoxidável	SS316 (A4)	$\ge 800$ MPa	$\ge 600$ MPa	140–200 HV

• Dimensions & Global Size Conversion
• Technical Standard: Longze provides high-precision flat-head socket screws manufactured to DIN 7991, ISO 10642, and ASME B18.3 standards. These screws feature a $90^\circ$ countersunk angle (Metric) or $82^\circ$ (Imperial) for a perfectly flush fit in precision machinery and architectural assemblies.

• American Size (Inch)	Nearest Metric Size (M)	Shank Dia. (mm/inch)	Head Dia. (dk) (mm/inch)	Hex Key Size (s) (mm/inch)
  #4 - 40	M3	3.00 mm / 0.112"	6.00 mm / 0.230"	2.0 mm / 1/16"
  #6 - 32	M3.5	3.50 mm / 0.138"	7.00 mm / 0.270"	2.5 mm / 5/64"
  #8 - 32	M4	4.00 mm / 0.164"	8.00 mm / 0.315"	2.5 mm / 3/32"
  #10 - 24	M5	5.00 mm / 0.190"	10.0 mm / 0.375"	3.0 mm / 1/8"
  1/4" - 20	M6	6.00 mm / 0.250"	12.0 mm / 0.500"	4.0 mm / 5/32"
  5/16" - 18	M8	8.00 mm / 0.312"	16.0 mm / 0.625"	5.0 mm / 3/16"
  3/8" - 16	M10	10.0 mm / 0.375"	20.0 mm / 0.750"	6.0 mm / 7/32"
  1/2" - 13	M12	12.0 mm / 0.500"	24.0 mm / 0.937"	8.0 mm / 5/16"

• Surface Treatment

• Coating	Process	Salt Spray	Aplicativo
  Black Oxide	Chemical	24–48h	Internal High-Strength
  Zinc Plated	Electroplating	72–144h	General Industrial
  Dacromet	Zinc-Flake	1000+h	Automotive / Outdoor
  Passivated	Chemical	1000+h	Stainless Steel / Medical