Our DIN 7991 Hexagon Socket Countersunk Head Screws (also known as flat head socket cap screws) are precision-engineered fasteners designed to sit completely flush with or below the workpiece surface. Featuring a flat 90° countersunk head and an internal hexagon socket drive, these screws provide a smooth, snag-free finish while delivering high clamping force through efficient torque transmission .
Manufactured in strict compliance with DIN 7991 (equivalent to ISO 10642) standards, these screws are ideal for applications requiring aesthetic appearance, space clearance, or safety from protruding heads
Product Details
Name | Hexagon Socket Countersunk Head Screws | Materials | Carbon Steel/Stainless Steel |
Standards | DIN7991/ISO10642 | Strength level | 4.8 8.8 10.9 12.9 A2-70 A4-70 A4-80 |
Size | M3-M24 | Surface finish | ZP/YZP/Black/Teflon/HDG/Dacromet |
Length | 6-200 | Samples | Available |
Product Parameters

| Screw Thread | M3 | M4 | M5 | M6 | M8 | M10 | M12 | (M14) | M16 | (M18) | M20 | (M22) | M24 | |
| d | ||||||||||||||
| P | Pitch | 0.5 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | 2.5 | 2.5 | 3 |
| α | tol.(+2) | 90° | 90° | 90° | 90° | 90° | 90° | 90° | 90° | 90° | 90° | 90° | 60° | 60° |
| b | L≤125 | 12 | 14 | 16 | 18 | 22 | 26 | 30 | 34 | 38 | 42 | 46 | 50 | 54 |
| 125<L ≤ 200 | / | / | / | 24 | 28 | 32 | 36 | 40 | 44 | 48 | 52 | 56 | 60 | |
| L>200 | / | / | / | / | / | 45 | 49 | 53 | 57 | 61 | 65 | 69 | 73 | |
| dk | max=nominal size | 6 | 8 | 10 | 12 | 16 | 20 | 24 | 27 | 30 | 33 | 36 | 36 | 39 |
| min | 5.7 | 7.64 | 9.64 | 11.57 | 15.57 | 19.48 | 23.48 | 26.48 | 29.48 | 32.38 | 35.38 | 35.38 | 38.38 | |
| ds | max=nominal size | 3 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 |
| min | 2.86 | 3.82 | 4.82 | 5.82 | 7.78 | 9.78 | 11.73 | 13.73 | 15.73 | 17.73 | 19.67 | 21.67 | 23.67 | |
| e | min | 2.3 | 2.87 | 3.44 | 4.58 | 5.72 | 6.86 | 9.15 | 11.43 | 11.43 | 13.72 | 13.72 | 16 | 16 |
| k | max | 1.7 | 2.3 | 2.8 | 3.3 | 4.4 | 5.5 | 6.5 | 7 | 7.5 | 8 | 8.5 | 13.1 | 14 |
| s | Nominal Size | 2 | 2.5 | 3 | 4 | 5 | 6 | 8 | 10 | 10 | 12 | 12 | 14 | 14 |
| min | 2.02 | 2.52 | 3.02 | 4.02 | 5.02 | 6.02 | 8.025 | 10.025 | 10.025 | 12.032 | 12.032 | 14.032 | 14.032 | |
| max | 2.1 | 2.6 | 3.1 | 4.12 | 5.14 | 6.14 | 8.175 | 10.175 | 10.175 | 12.212 | 12.212 | 14.212 | 14.212 | |
| t | max=nominal size | 1.2 | 1.8 | 2.3 | 2.5 | 3.5 | 4.4 | 4.6 | 4.8 | 5.3 | 5.5 | 5.9 | 8.8 | 10.3 |
| min | 0.95 | 1.55 | 2.05 | 2.25 | 3.2 | 4.1 | 4.3 | 4.5 | 5 | 5.2 | 5.6 | 8.44 | 9.87 | |
Key Features & Benefits
Flush-Mount Design: The 90° countersunk head sits level with the workpiece surface after installation, eliminating snag hazards and enabling smooth mating of assembled parts
High Torque Transmission: Internal hexagon socket drive allows for superior torque transfer compared to slotted or Phillips drives, reducing cam-out and driver wear
Multiple Material Grades: Available in carbon steel (Grades 8.8, 10.9, 12.9) and stainless steel (304/A2-70, 316/A4-80) for diverse application requirements
Corrosion Resistant Finishes: Zinc plated (blue, white, yellow), hot-dip galvanized, black oxide, Dacromet, or plain stainless steel for various environmental conditions
Full Thread Coverage: Fully threaded design ensures maximum thread engagement and holding power throughout the entire screw length
DIN 7991 / ISO 10642 Compliance: Manufactured to strict dimensional standards ensuring interchangeability and consistent quality worldwide
Intended Applications
Industrial & Machinery: Equipment assembly, machine tooling, conveyor systems, and security guarding
Automotive: Interior components, engine accessories, chassis assemblies
Construction & Architecture: Curtain wall installation, aluminum framing, metal cladding, and facade systems
Electronics & Enclosures: Server racks, control cabinets, instrument housings, and electronic device assembly
Marine & Offshore: Boat deck fittings, offshore platform components, coastal infrastructure
Medical Equipment: Surgical instruments, diagnostic devices, laboratory equipment (A4 stainless recommended)
Furniture & Joinery: Metal furniture assembly, decorative hardware, and concealed fastening applications
Installation Guidelines
1.Prepare Countersink Hole: For optimal flush seating, the workpiece requires a 90° countersink matching the screw head angle
2.Select Correct Tool: Use the appropriate metric hex key (Allen wrench) that fits snugly into the socket drive to prevent stripping
3.Avoid Over-Torque: Due to the head geometry, these screws have lower load-bearing capacity than standard cap screws. Follow torque specifications for the grade and size
4.Use Anti-Seize for Stainless: Apply lubricant or anti-seize compound when installing stainless steel screws to prevent thread galling
5.Check Flushness: After installation, the head should sit flush with or slightly below the workpiece surface
Why Choose Our DIN 7991 Countersunk Screws?
Standards Compliant: Full compliance with DIN 7991 and ISO 10642 specifications
Comprehensive Range: All standard metric sizes from M3 to M24 in stock
Multiple Materials: Carbon steel (8.8-12.9) and stainless steel (304/316) available
Quality Assurance: Rigorous dimensional and mechanical testing; material certifications (EN 10204 3.1) available upon request
Bulk & Retail Quantities: Suitable for both small projects and large industrial orders
Technical Support: Expert guidance on grade selection, torque values, and application engineering
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