The Hex Socket Head Cap Screw (also known as an Allen bolt or DIN 912 socket screw) is an essential high-precision structural fastener designed for counterbored installations, heavy industrial machinery, injection mold tooling, automotive drive systems, and robotics. Engineered from premium alloy steel (such as 35CrMo, 42CrMo, or SCM435) and hardened through advanced thermal processing, this fastener delivers high torque transmission, exceptional shear resistance, and compact head geometry in accordance with international ISO standards.
Technical Specifications of Hex Socket Head Cap Screw
High tensile property classes (Grade 8.8, Grade 10.9, and Grade 12.9) guarantee heavy load-bearing limits. Grade 12.9 socket head cap screws represent the highest strength class in commercial fasteners, engineered with a minimum tensile strength of 1220 MPa and a yield strength of 1100 MPa to prevent loosening or fatigue under extreme mechanical vibration.
| Property Rating | Alloy Material Grade | Tensile Strength (Min) | Yield Strength (Min) | Hardness Rating (HRC) |
|---|---|---|---|---|
| Grade 8.8 | Medium Carbon Steel / 40Cr Steel | 800 N/mm² (800 MPa) | 640 N/mm² (640 MPa) | 22 – 32 HRC |
| Grade 10.9 | Alloy Steel (40Cr / 35CrMo) | 1040 N/mm² (1040 MPa) | 940 N/mm² (940 MPa) | 32 – 39 HRC |
| Grade 12.9 | High Alloy Steel (35CrMo / SCM435 / 42CrMo) | 1220 N/mm² (1220 MPa) | 1100 N/mm² (1100 MPa) | 39 – 44 HRC |
Precision Forging and Heat Treatment for Hex Socket Head Cap Screw
At our advanced manufacturing facility in Handan, China, every Grade 8.8 and 12.9 socket head cap screw undergoes a multi-pass cold forging and metallurgical refinement process:
- Internal Socket Cold Extrusion: High-precision multi-station formers cold-extrude the internal hex recess and head knurling to precise tolerances, preventing Allen key rounding under high assembly torque.
- Continuous Controlled-Atmosphere Heat Treatment: Fasteners undergo quenching in specialized polymer oil followed by precision tempering to achieve a homogeneous martensitic grain structure with zero surface decarburization.
- Precision Thread Rolling: Threads are rolled post heat treatment (or pre-heat treatment per spec) to establish smooth 6g metric pitch tolerances that ensure low friction and high fatigue strength.
- Surface Coating & Anti-Corrosion: Standard black oxide finish with anti-rust oil immersion, or optional electro-zinc plating, Dacromet, and Geomet coatings for enhanced environmental durability.
Industrial Applications of Hex Socket Head Cap Screw
The compact cylindrical head design allows hex socket head cap screws to sink completely into counterbored holes, making them ideal for space-restricted, high-load engineering assemblies:
- Injection Molding & Stamping Dies: Fastening heavy mold plates, die bases, and punch blocks subjected to repetitive cyclic clamping forces.
- Automotive & Hydraulic Machinery: Securing cylinder heads, high-pressure hydraulic pumps, transmission housings, and engine components.
- Robotics & Precision Tooling: CNC machine tool building, linear guide rail positioning, and automated assembly arms.
Quality Assurance and Export Packaging for Hex Socket Head Cap Screw
Handan YiHao Fastener enforces comprehensive Quality Control (QC) protocols for all export shipments. Inspection procedures include Rockwell C (HRC) hardness testing, internal hex key fit and depth verification, thread ring gauge pass/fail checks, and wedge tensile testing.
All export items are packed in heavy-duty 25kg inner cartons, neatly stacked on ISPM 15 compliant fumigated wooden pallets, and wrapped in protective stretch film for ocean shipment.
Request Factory Direct Pricing for Hex Socket Head Cap Screws
Looking for a trusted manufacturer in Handan, China for Grade 8.8, 10.9, or 12.9 hex socket head cap screws (DIN 912)? Contact Handan YiHao Fastener today for technical datasheets, CAD drawings, full thread/partial thread options, and direct bulk export quotes.
