LONGZE DIN 7991 Hex Socket Flat Head Bolts represent the industrial benchmark for high-strength, flush-surface fastening solutions. Engineered with a precision 90-degree countersunk head, these bolts ensure a seamless, smooth finish critical for precision machinery and structural assemblies where head protrusion is unacceptable. Utilizing an internal hex drive, the DIN 7991 delivers superior torque transmission without the interference associated with standard hex bolts.
As a core component of the GFM-WCR System, our DIN 7991 series is manufactured to stringent Class 8.8, 10.9, and 12.9 property requirements. By integrating advanced cold-heading technology and automated depth control, LONGZE provides absolute dimensional integrity for demanding applications in the automotive, aerospace, and mold-making sectors, ensuring reliable performance under extreme mechanical stress.
Detailed Parameters
| Diameter Range | M3 – M24 | Property Class | Grade 8.8, 10.9, 12.9 |
|---|---|---|---|
| Head Angle | 90° Degree (±2°) | Thread Class | ISO 6g (Precision) |
| Base Materials | SCM435 / Carbon Steel | Drive Variant | Hex Socket / TX Drive (Torx) |
| Surface Finishes | Black Oxide, Zinc Plated, Dacromet | Special Coatings | Nickel, Teflon, Geomet |
| Standard Mapping | DIN 7991 ➔ ISO 10642 | Quality Audit | Go/No-Go Gauge & Tensile Test |
Key Advantages
High-Tensile Strength
Certified Class 10.9 and 12.9 materials ensure maximum load capacity for heavy-duty industrial applications.
Corrosion Resilience
Advanced Zinc-Flake and Geomet coatings provide superior salt spray resistance in harsh environments.
Flush-Fit Precision
Precisely calibrated 90° head angle guarantees a perfectly centered, smooth surface installation.
Anti-Stripping Design
Optimized socket depth prevents tool slipping and stripping during high-torque fastening operations.
Hydrogen Embrittlement Control
Strict post-plating baking protocols eliminate risk of sudden failure in high-grade 10.9/12.9 screws.
Full Traceability
GFM-WCR system links every batch to the original alloy steel wire-rod heat number for total quality assurance.
Product Gallery
Management Platforms
Technical Data HUB
Access full dimensional matrices and engineering specifications for the DIN 7991 series.
Inventory PRO Node
Real-time tracking of metric bolt stock for immediate industrial repair and supply.
Deflection HUB
Deep-dive research into high-tensile science and failure mitigation strategies.
GFM-WCR Traceability
Digital mapping of raw material heat numbers to finished product batches.
Global Logistics Node
Rapid DDP/CIF coordination for shipments to Malaysia, Argentina, and beyond.
Standard Mapping Layer
Professional tech-gap analysis for DIN 7991 to ISO 10642 conversion.
Investment Return Comparison
| Metric | Standard Grade Fasteners | LONGZE GFM-WCR System |
|---|---|---|
| Installation Fit | Potential Protrusion | Absolute Flush-Surface |
| Failure Rate | Moderate (Tool Stripping) | Ultra-Low (Precision Socket) |
| Corrosion Life | Standard Zinc Coating | Enhanced Zinc-Flake/Geomet |
| Supply Chain | Generic Sourcing | Full Traceability/Ready Stock |
| Risk Level | High (Hydrogen Embrittlement) | Mitigated (Strict Baking) |
Frequently Asked Questions
DIN 7991 is the German industrial standard for countersunk hex socket head screws, while ISO 10642 is the international equivalent. They are largely interchangeable, but LONGZE provides a detailed tech-gap analysis to ensure perfect compatibility for your specific project.
For high-tensile fasteners (Class 10.9 and 12.9), we implement strict baking protocols immediately after the zinc plating process to drive out hydrogen, preventing brittle failure under load.
For extreme corrosion resistance, we recommend Dacromet or Zinc-Flake coatings. These offer significantly higher salt spray resistance compared to standard zinc plating and are ideal for photovoltaic brackets and outdoor structures.
Yes, our DIN 7991 series is engineered for aerospace sectors, utilizing high-grade SCM435 alloy steel and rigorous QC audits (tensile and hardness testing) to meet strict dimensional integrity requirements.
Our GFM-WCR system pairs DIN 7991 bolts with ISO 4032 Hexagon Nuts for standard assemblies and ISO 10511 Nylon Lock Nuts for applications requiring vibration resistance.
The standard head angle for DIN 7991 is 90 degrees, with a tolerance of ±2°, ensuring a precise flush fit when installed into a matching countersunk hole.
English 
Afrikaans 
Arabic 
Bengali 
Bulgarian 
French 
German 
Hindi 
Indonesian 
Italian 
Japanese 
Korean 
Malay 
Portuguese 
Russian 
Spanish 
Thai 
Turkish 
Urdu 
Vietnamese 
