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Hexagon Socket Head Cap Bolt DIN 912 - High Quality Carbon & Alloy Steel Bolts from China Suppliers & Factory
| Product name | Hexagonal socket screw |
| Size | M6/M8/M10/M12 |
| Grade | 4.8/8.8/10.9/12.9 |
| Material | Steel/Stainless Steel |
| Surface treatment | YZP |
| Standard | DIN/ISO |
| Certificate | ISO 9001 |
| Sample | Free Samples |
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Definition and Structural Characteristics
Definition: An internal hexagonal screw is a fastener with a hexagonal groove (internal hexagonal hole) on the head, which requires the use of an Allen Key or a hexagonal screwdriver head matched with an electric tool for installation and removal.
Structural features:
- Head types: common cylindrical heads (such as ISO 4762/DIN 912), countersunk heads (such as DIN 7991), flat heads, etc., suitable for different installation requirements (such as countersunk heads used in scenarios where flush surfaces are required).
- Thread type: full thread or half thread, with various materials and surface treatments.
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Materials and Surface Treatment
Common materials:
- Carbon steel (such as 8.8 grade, 12.9 grade): high strength, used in machinery and automobiles.
- Stainless steel (304/316): corrosion-resistant, suitable for outdoor and medical equipment.
- Titanium alloy: lightweight, high corrosion resistance, used in aerospace.
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Application Scenarios
- Industrial field: machine tools, molds, automation equipment (high-strength connections that require frequent disassembly).
- Automotive/Aviation: Engine components, chassis (high temperature resistance, vibration resistance).
- Consumer electronics: laptops, cameras (precision small-sized screws, such as M1.6).
- Furniture/Bicycle: IKEA furniture assembly, bicycle brake system (countersunk anti scratch).
💡 Usage Tips
- The wrench should be fully inserted into the bottom of the hole to avoid sliding teeth caused by oblique force.
- When pre drilling, countersunk screws need to match the taper (such as 90°).
- Regularly check the torque (using a torque wrench) to prevent over tightening or loosening.
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Frequently Asked Questions
QWhat is the difference between a hexagonal socket screw and a standard hex bolt?
A hexagonal socket screw (Allen screw) has an internal hex recess in the head that requires an Allen key for installation. A standard hex bolt has an external hexagonal head driven by a spanner or wrench. Allen screws are preferred where a low-profile or flush surface is required and clearance for an external wrench is unavailable.
QWhat strength grades are available, and how do I choose the right one?
Common grades are 4.8, 8.8, 10.9, and 12.9. Higher numbers indicate greater tensile strength. Grade 8.8 suits general industrial use, grade 10.9 is used in structural and automotive applications, and grade 12.9 is reserved for the most demanding loads such as engine assemblies and high-stress machinery.
QWhich material is best for outdoor or corrosive environments?
Stainless steel 304 or 316 is recommended for outdoor, marine, or chemically aggressive environments. Grade 316 contains molybdenum, providing superior resistance to chlorides and saltwater. Titanium alloy is the choice for extreme weight-sensitive or highly corrosive aerospace applications.
QWhat does YZP surface treatment mean?
YZP stands for Yellow Zinc Plating — a zinc electroplating process with a yellow chromate passivation layer. It provides a corrosion-resistant barrier and gives the fastener its characteristic golden-yellow color. It is widely used on carbon steel screws for general-purpose and mild-outdoor environments.
QWhat international standards do these screws comply with?
Our hexagonal socket screws are manufactured to DIN and ISO standards, including ISO 4762 / DIN 912 for cylinder-head cap screws and DIN 7991 for countersunk variants. All products are produced under an ISO 9001 certified quality management system to ensure consistent dimensional accuracy and mechanical performance.
QHow do I prevent stripping or rounding when tightening these screws?
Always insert the Allen key fully to the base of the socket and keep it perpendicular to the fastener — applying force at an angle is the primary cause of rounding. Use the correct key size. For critical joints, use a calibrated torque wrench to apply the specified torque value and avoid over-tightening, which can shear threads or fracture the fastener.