Flat Head Hex Socket Bolt: Structural Features, Application Scenarios and Selection Guide

What is a Flat Head Hex Socket Bolt?

Flat Head Hex Socket Bolt, also known as Hex Socket Bolt, is a screw with a hexagonal hole on the head. It is usually tightened or loosened using a hexagonal wrench or a power tool with a hexagonal head. This design makes the hexagonal cylindrical head screw very suitable for use in small spaces. It has high torque transmission capacity and stability and is suitable for occasions that require a close fit.

Structural features of Flat Head Hex Socket Bolt

Head design - The head is designed with a hexagonal hole, which can be operated with a hexagonal wrench or power tools, and is particularly suitable for use in small spaces.

Torque transmission - The hexagonal design provides greater torque transmission capacity and is more stable when subjected to outward pulling force than the hexagonal screw.

Aesthetics - The hexagonal hole will not be exposed after installation, and the appearance is more beautiful, which is suitable for product assembly with high appearance requirements.

Material and grade - Hexagonal cylindrical head screws are usually made of carbon steel, stainless steel or alloy steel. Stainless steel materials include SUS202, SUS304 and SUS316. According to the strength grade, hexagonal cylindrical head screws are divided into 4.8, 8.8, 10.9 and 12.9 grades, etc. High-strength grade screws are usually used in applications that require higher tightening force.

Optional surface treatment - blackening, electroplating, Dacromet, oxidation, etc., to improve corrosion resistance and wear resistance.

Application Scenarios of Flat Head Hex Socket Bolt

Due to its unique design and excellent performance, Flat Head Hex Socket Bolt is widely used in many fields. The following are some of the main application scenarios of hexagon socket head screws:

1. Mechanical equipment

In automobile manufacturing, Flat Head Hex Socket Bolt is used to fix engine parts, suspension systems, etc.; when assembling electronic equipment, these screws help stabilize circuit board components.

2. Construction industry

In the construction industry, Flat Head Hex Socket Bolt is one of the indispensable connectors, widely used in doors and windows, furniture manufacturing and other fields.

3. Electronic products

In the assembly of electronic products, Flat Head Hex Socket Bolt is used to connect electronic components and housings. Its compact design and beautiful appearance make it very popular in electronic products that require fine assembly

4. Furniture assembly

Flat Head Hex Socket Bolt is also widely used in furniture assembly, such as office desks, bookcases, bed frames, etc. Its easy-to-hide cylindrical head design makes the furniture look neater and more beautiful after assembly.

Structural characteristics of Flat Head Hex Socket Bolt

1. Raw material selection

Carbon steel (4.8/8.8/10.9/12.9) - suitable for mechanical structures and general equipment.

Stainless steel (304/316) - suitable for anti-corrosion environments, such as outdoor, chemical equipment, etc.

Alloy steel (42CrMo, SCM435) - suitable for high-strength, impact-resistant applications, such as automobiles and machine tools.

Titanium alloy (TC4) - suitable for lightweight and high-end applications, such as aerospace, medical equipment, etc.

2. Cold heading

Use a multi-station cold heading machine for one-time forming to ensure the integration of the head and the rod and improve the strength of the bolt.

3. Turning & threading

Use CNC precision turning to ensure the head angle and dimensional tolerance.

The thread adopts rolling process to improve surface finish and fatigue resistance.

4. Heat treatment

Quenching and tempering treatment (quenching + tempering) to improve strength and toughness, suitable for bolts of grade 8.8 and above.

Solution treatment, used for stainless steel bolts, to improve corrosion resistance.

5. Surface treatment

Blackening treatment: Enhance rust resistance, suitable for indoor equipment.

Galvanizing (blue and white zinc/color zinc/black zinc): Suitable for mechanical equipment with general anti-corrosion requirements.

Dacromet: Strong salt spray resistance, suitable for long-term outdoor environments such as automobiles and bridges.

Oxidation treatment: Improve the high temperature and corrosion resistance of bolts.

PVD coating (for titanium alloy): Enhance wear resistance and reduce friction coefficient.

6. Quality inspection

Dimension inspection: bolt length, head angle, thread accuracy.

Strength inspection: tensile test, hardness test, torsion test.

Surface inspection: salt spray test, wear test.

Industry Standards for Flat Head Hex Socket Bolts

ISO 4762 - 2004 - International standard for Flat Head Hex Socket Bolts, specifying metric dimensions and tolerances.

GB/T 70.1 - Chinese national standard, covering the specifications and performance of metric countersunk hex socket bolts.

DIN 912 - German standard, suitable for high-strength hex socket bolts in the machinery and mold industries.

ASME/ANSI B18.3 - 1986 - American standard, suitable for imperial hex socket bolts.

How to choose the right Flat Head Hex Socket Bolt?

1. Choose the right material

General equipment: carbon steel (grade 8.8/10.9) + galvanizing or blackening treatment.

High strength requirements: alloy steel (grade 12.9) + quenching and tempering treatment.

Anti-corrosion requirements: 304/316 stainless steel + polishing or Dacromet coating.

Lightweight requirements: titanium alloy + PVD coating.

2. Choose the right specifications

Determine the head angle, thread size and length according to the standard.

Choose full thread or partial thread to meet different installation requirements.

3. Determine the surface treatment

Indoor environment: blackening, electrogalvanizing.

Outdoor environment: Dacromet, electronickel plating.

High temperature conditions: PVD coating or oxidation treatment.