Perfect Flush Surface Installation
The 90° countersunk head sits completely flush with the workpiece, eliminating protrusions and preventing interference, friction, or snagging in moving assemblies.
DIN 7991 Hexagon Socket Countersunk Head Cap Screw
- Standard: DIN 7991
- Material: SUS304, SUS316, SUS410, Carbon Steel
- Thread Size: M3-M24
- Surface Treatment: Plain, Zinc Plated, HDG, Dacromet, Ruspert
- Min Order: 5000pcs
- Sample: Free sample (after quote)
- Delivery time: 30 – 45 Days
Product Overview
Product Application
DIN 7991 is the most classic countersunk fastener in German industrial standards, representing hexagon socket countersunk head screws. Its key feature is a flat, 90° conical countersunk head with a regular hexagonal recess integrated at its center. This design allows for high-torque tightening using a hex wrench.
The countersunk head ensures that the screw sits completely flush with the material surface after installation, while the hexagon socket drive effectively transmits torque and facilitates assembly in areas with limited space.
Designed specifically for applications requiring a flush surface finish, compact installation spaces, and reliable clamping performance, these screws are widely used in machinery, automotive components, electrical equipment, molds, and precision assemblies.
Draw
Specification
Key Specifications and Parameters
- Equivalent Standard: Has been updated and replaced by ISO 10642 by the International Organization for Standardization (the corresponding Chinese national standard is GB/T 70.3).
- Drive Type: Hexagon Socket (Hex), which prevents the fastening tool from slipping. Thread Type: Metric coarse thread. Short lengths are typically fully threaded, while long lengths are partially threaded.
- Common Strength Grades: High-strength carbon steel is typically Grade 10.9 or 12.9 (surfaces are usually blackened or galvanized); common stainless steel grades are A2-70 (304) and A4-80 (316).
- Note on Strength Reduction: Due to the smaller shear area of the countersunk head design, even when using Grade 10.9 or 12.9 high-strength steel, the actual tensile load-bearing capacity is approximately 20% lower than that of standard cylindrical-head screws of the same grade (such as DIN 912).
Product Advantages
High Torque Performance Without Slipping
The internal hex socket provides strong tool engagement and excellent torque transmission, reducing cam-out risk during high-strength tightening.
Self-Centering & Precision Alignment
The 90° conical head provides automatic positioning during installation, improving assembly accuracy, structural rigidity, and component alignment.
Common Questions
What is DIN 7991?
DIN 7991 is a standard for hexagon socket countersunk head cap screws with metric threads.
What is the equivalent standard of DIN 7991?
The replacement standard is DIN EN ISO 10642.
Can DIN 7991 screws be used outdoors?
Yes. Stainless steel versions are suitable for outdoor and corrosion-sensitive applications.
Can DIN 7991 screws be customized?
Yes. Custom sizes, materials, coatings, and packaging are available.
