DIN 7991 Countersunk Socket Head Screws
DIN 7991 Countersunk Socket Head Screws feature a 90° countersunk head that sits flush with the surrounding surface when properly installed. This head design keeps the fastening point smooth and unobtrusive, while the internal hex drive provides direct tool engagement without requiring additional space around the screw head.
The flush-fitting design is particularly useful for components where a protruding fastener could interfere with movement, assembly, or the finished surface. DIN 7991 screws are available in a range of metric sizes, including M3 to M24, with carbon and alloy steel as well as stainless steel options for different mechanical and environmental requirements. They are commonly used in machinery, equipment, metal components, brackets, fixtures, and precision mechanical assemblies where a clean surface finish and compact fastening arrangement are important.
Specification:
DIN 7991 screws combine a 90° countersunk head with an internal hexagon drive, allowing the fastener to sit below or level with the surrounding surface after installation. The product is available in metric thread sizes from M3 to M24, with thread dimensions based on the ISO metric system and a commonly used external thread tolerance of 6g. For steel versions, 8.8, 10.9, and 12.9 are available for applications requiring different levels of mechanical strength. Their tensile strength, yield strength, hardness, and other mechanical properties are controlled according to the relevant requirements of ISO 898-1. Stainless steel versions are available in A2 and A4, with material and mechanical properties covered by the applicable ISO 3506 requirements.
| Item | Specificaiton |
|---|---|
| Standard | DIN7991 |
| Product Type | Countersunk Socket Head Screw |
| Head Type | Countersunk |
| Head Angle | 90° |
| Drive | Internal Hexagon |
| Thread Standard | ISO261/ISO965 |
| Material | Carbon Steel,Alloy Steel,Stainless Steel |
| Property Class | 8.8,10.9,12.9 A2-70/80 A4-70/80 |
| Size Range | M3-M24 |
| Surface Treatment | Black Oxidation,Zinc Plated, Dacromet,Bright Finish, Passivation |
Dimension Chart of DIN7991 Countersunk Socket Head Screws:
The dimension chart covers the main dimensions of DIN 7991 screws, including thread diameter, pitch, screw length, head diameter, countersunk head height, and internal hexagon size. These dimensions determine how the screw fits into the threaded component and how deeply the countersunk head sits within the mating surface. For the traditional DIN 7991 dimensional series, the countersunk angle varies with size. Sizes from M3 to M20 use a 90° countersunk head, while M24 is specified with a 60° countersunk head in the corresponding DIN 7991 dimension table.
| Thread Diameter | M3 | M4 | M5 | M6 | M8 | M10 | M12 |
| P | 0.5 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 |
| dk max | 6 | 8 | 10 | 12 | 16 | 20 | 24 |
| dk min | 5.7 | 7.64 | 9.64 | 11.57 | 15.57 | 19.48 | 23.48 |
| e min | 2.3 | 2.87 | 3.44 | 4.58 | 5.72 | 6.86 | 9.15 |
| k max | 1.7 | 2.3 | 2.8 | 3.3 | 4.4 | 5.5 | 6.5 |
| s min | 2.02 | 2.52 | 3.02 | 4.02 | 5.02 | 6.02 | 8.025 |
| s max | 2.1 | 2.6 | 3.1 | 4.12 | 5.14 | 6.14 | 8.175 |
| t max | 1.2 | 1.8 | 2.3 | 2.5 | 3.5 | 4.4 | 4.6 |
| t min | 0.95 | 1.55 | 2.05 | 2.25 | 3.2 | 4.1 | 4.3 |
- RELATED SCREW LISTS:
- ANSI/ASME B18.3 Stainless Steel American Standard Countersunk Head Torx Screw
- ANSI/ASME B18.3 Stainless Steel Hexagon Socket Button Head Cap Screws
- ANSI/ASME B18.3F Stainless Steel Hex Socket Countersunk Head Machine Screw
- American Standard ASME/ANSI B18.3 Hexagon Socket Head Cap Screws
- ASME/ANSI B18.6.3 Cross Recessed Pan Head Machine Screws
- ISO7380 Stainless Steel Hexagon Socket Button Head Screws
- DIN963 90° Stainless Steel Slotted Countersunk Head Screws
- DIN965 Stainless Steel Cross Recessed Countersunk Head Screws
- DIN84 Stainless Steel Slotted Cheese Head Screws
- DIN7971 Stainless Steel Slotted Pan Head Tapping Screws
- DIN7981 Cross Recessed Pan Head Tapping Screws
- DIN7972 Stainless Steel Slotted Countersunk Head Tapping Screws
Application of DIN7991 Countersunk Socket Head Screws:
Flush Surface Assemblies
DIN 7991 screws are a good fit when the fastener must disappear into the component rather than remain above it. After the correct countersink is machined, the 90° head can sit flush with the surrounding surface. This is useful for covers, plates, sliding surfaces, panels, and components where a projecting screw head could interfere with the finished part.
Moving and Sliding Components
A flush screw head is particularly useful around parts that move across, rotate near, or come into contact with another surface. Recessing the fastener removes a potential obstruction and leaves a more continuous working surface. This makes DIN 7991 suitable for machine guides, covers, sliding plates, fixtures, and similar assemblies.
Recessed and Hard-to-Reach Fastening
The combination of a countersunk head and internal hexagon drive is useful when the screw needs to be recessed while still being tightened from the top. This arrangement works well for jigs, molds, machine plates, brackets, and compact assemblies where there is limited clearance around the fastening point.