Flat Head Hex Bolt

High-quality Flat Head Hex Bolt with a cheap price can be wholesaled from our factory called Gangtong Zheli, which is a leading manufacturer and supplier in China. A flat head hex bolt is a special fastener that combines a hexagonal drive head with a countersunk (tapered) head design.  Its head is conical (typically 82° or 90°) and can be embedded in a pre-machined countersunk hole, allowing for flush mounting and preventing protrusion that could affect appearance or cause interference.

flat head hex bolt is widely used in fields requiring high demands on aesthetic appearance, space efficiency, and structural strength, such as precision machinery, automation equipment, electronic enclosures, rail transportation, medical devices, high-end furniture, and aerospace. Its unique design not only enhances the aesthetic appeal of the assembly but also strengthens the shear and vibration resistance of the connection, making it an indispensable key component in modern precision assembly.

Core Performance and Technological Advantages

Based on our years of experience in precision fastener research and development, on-site customer technical support, and automated assembly services, our countersunk hex head bolts offer the following core advantages in structural design, material selection, and process control:

1. Precise Countersunk Design for Flush Mounting

- Standard 82°/90° cone angle: Perfectly matches the countersunk hole, ensuring the bolt head is flush with the workpiece surface after installation.

- Reduced space occupation: Suitable for confined spaces or assembly scenarios requiring a smooth surface.

- Interference avoidance: Prevents moving parts from scratching or affecting surface flatness.

2. Hexagonal Internal/External Drive Design for Improved Assembly Efficiency

- External hex head: Supports quick tightening with sockets or wrenches, suitable for automated assembly lines.

- Optional internal hex socket version: Further reduces head height, suitable for ultra-thin structures.

- Compatible with electric/pneumatic tools, increasing production efficiency by over 30%.

3. High-Strength Materials and Precision Manufacturing for Reliable Connections

- Material Selection:

- Carbon steel (Grade 8.8, Grade 10.9): General purpose, suitable for mechanical structures.

- Alloy steel (35CrMoA, 40Cr): High strength, used for heavy-duty connections.

- Stainless steel (A2-70, A4-80): Corrosion resistant, suitable for outdoor, food, and medical equipment.

- Manufacturing Process:

- Cold heading: Continuous metal flow lines, improving tensile strength.

- High-precision thread rolling: Thread accuracy up to 6g grade, ensuring stable fit.

- Heat treatment control: Surface hardness HRC 32–45, good core toughness.

4. Multiple Surface Treatments to Meet Different Environmental Requirements

- Environmentally friendly electroplating (blue-white zinc, colored zinc): Salt spray test ≥ 96 hours, suitable for general industrial environments.

- Dacromet: Chromium-free coating, corrosion resistance ≥ 500 hours, no hydrogen embrittlement risk.

- Hot-dip galvanizing: Suitable for structures exposed to the outdoors for extended periods.

- Natural/polished stainless steel: Meets food-grade or medical-grade hygiene requirements.

5. Anti-loosening and Sealing Design (Optional)

- Nylon locking ring: Provides pre-tensioning force to prevent loosening due to vibration

- Integrated sealing washer design: For waterproof and dustproof connections

- Full thread or partial thread options: Adaptable to different connection thicknesses

6. Full-process quality control to ensure consistency

- Raw material spectral analysis and mechanical testing

- In-line production process inspection (dimensions, hardness, thread gauge)

- 100% finished product visual inspection and sample destructive testing

- Material certificates, test reports, and certificates of conformity provided for each batch

Typical Application Scenarios

Our countersunk hex head bolts have been successfully applied in several demanding fields, helping customers achieve precise assembly, aesthetically pleasing connections, and long-term reliability:

Precision machinery: Used in CNC equipment and robot joints, ensuring compact structure

Rail transit: Interior panels and control box installation, ensuring flush surface, safety and aesthetics

Medical equipment: Operating tables and imaging equipment, meeting sterile and smooth surface requirements

Electronic enclosures: Server cabinets and control boxes, improving heat dissipation and ease of maintenance

Aerospace: Cabin component connections, combining lightweight design with high strength

Why choose our flat head hex bolts? Authoritative Certification, Quality Assurance

- Certified with international standards such as ISO 9001, IATF 16949, ISO 17025, CE, RoHS, and REACH

- Products comply with multiple national standards including GB, ISO, DIN, and ANSI, and are exported to Europe, America, Japan, South Korea, and Southeast Asia.

- SGS and BV third-party testing reports are available.

Self-owned Intelligent Manufacturing Production Line, Controllable Process

- Self-built full-process production line including cold heading, heat treatment, thread rolling, surface treatment, and testing laboratory.

- Equipped with spectrometers, universal material testing machines, salt spray chambers, metallographic microscopes, and torque testers.

- Achieves full traceability management from raw materials to finished products.

Professional Technical Support and Customization Services

- Provides selection suggestions, torque parameter tables, installation guidance videos, and CAD drawings.

- Supports non-standard customization (special length, thread, head angle).

- Offers OEM labeling, JIT just-in-time delivery, and bulk supply services.

- Technical team provides 24-hour response to solve problems such as installation, loosening, and corrosion.

Genuine Customer Reviews and Industry Reputation

“The countersunk head has high precision, is perfectly flush after installation, and significantly improves the appearance.” – A precision equipment manufacturer

“The stainless steel version has good corrosion resistance and is very reliable for medical equipment.” – A medical technology company

“Supports customization, timely delivery, and professional service.” – A rail transit supplier

FAQ

Q1: What is the countersunk angle of the flat head hex bolt?

A: Commonly 82° or 90°, which needs to match the countersunk hole angle of the workpiece.

Q2: Can it be used for connecting stainless steel plates?

A: Yes, it is recommended to use A4-80 stainless steel material to avoid galvanic corrosion.

Q3: Is pre-tightening force control required?

A: Yes, for high-strength models (such as grade 10.9), it is recommended to use a torque wrench to control the pre-tightening force.

Q4: How to prevent bolt loosening?

A: Optional nylon locking rings, flange washers, or thread adhesives can enhance anti-loosening performance.

Q5: What are the minimum order quantity and delivery time? 

A: Standard products require a minimum order of 100 pieces. Samples ship in 5-7 days, and bulk orders in 15-30 days. Expedited shipping is available.