Part 1: Technical Background and Industry Position

Handan Guangxuan Fastener Manufacturing Co., Ltd. is located in Yongnian, Hebei——a well-known domestic base for standard fastener industry. Relying on the three-dimensional transportation network of Jingguang Railway, National Highway 107, Beijing-Hong Kong-Macau Expressway, and Qinghong Expressway, the company has achieved efficient logistics connectivity. As a local fastener manufacturing entity with outstanding professional strength, the company has been deeply involved in the custom processing field for many years, mainly producing products such as tower crane bolts, high-strength bolts, double-end bolts, and high-strength nuts. The OEM business of 8.8-grade carbon steel external hexagon nuts has become an industry benchmark with its technical advantages and quality assurance.

Section 2, 8.8 Grade Carbon Steel External Hex Nuts Technical Analysis

1. Material Selection and Performance Parameters
Grade 8.8 carbon steel nuts are made of medium carbon steel (such as 35#, 45# steel) as raw material, after heat treatment, the hardness reaches HRC22-32, tensile strength ≥800MPa, yield strength ≥640MPa, in compliance with GB/T 6170 standard. Their core advantage lies in the balanced combination of high strength and good toughness, suitable for heavy-load scenarios such as tower cranes, bridges, etc.

2. Production Process Flow
STEP 1: Raw Material Inspection - Analyze chemical composition with a spectrometer to ensure carbon content of 0.32%-0.45%.
STEP 2: Cold heading forming - one-time forming with a multi-station cold heading machine, ensuring thread accuracy up to 6g grade.
STEP3: Heat Treatment - Quenching and tempering treatment through a continuous mesh belt furnace, controlling deformation ≤0.1mm.
STEP 4: Surface Treatment - Optional galvanized (salt spray test ≥ 72 hours) or Dacromet (no red rust for 500 hours), meeting different anti-corrosion requirements.

3. Quality Control System
The company establishes a full-process standardized management system, setting up 12 quality inspection checkpoints from raw material entry to finished product delivery, including:
Dimension inspection: Three-coordinate measuring machine accuracy ±0.01mm.
Performance Test: Universal material testing machine with a tensile speed of 5mm/min.
- Thread gauge inspection: 100% full inspection ensures interchangeability.

3. Corporate Technical Layout and Application Experience

1. Equipment investment and production capacity guarantee
Equipped with 30 cold heading presses ranging from 200T to 1000T, 5 belt furnaces, and 2 fully automatic electroplating lines, the monthly production capacity reaches 5 million pieces, capable of flexibly handling small batch orders (≥1,000 pieces) and large batch orders (≥1 million pieces).

2. Non-standard customization capability
For customers' special requirements, we offer custom services based on provided samples or drawings. We have developed a M48×300mm super-long nut for a wind power company, resolved the deformation issue through optimized heat treatment process, and increased the pass rate of finished products to 99.2%.

3. Typical Application Cases
After adopting 8.8-grade nuts from Guangxuan's OEM, the equipment failure rate decreased by 40%, and the annual maintenance cost of each tower crane was reduced by approximately 20,000 yuan. Reviewing the key improvements included:
- Improved thread fit accuracy: Optimized from 7H grade to 6H grade, reducing the risk of loosening.
- Corrosion resistance upgraded: Dacromet treatment replaces regular galvanized coating, salt spray test time extended threefold.

4. Technical Challenges and Solutions

FAQ: How to control the heat treatment deformation of large-size nuts?
Answer: By using a segmented quenching process (850℃ water quench + 400℃ oil quench) combined with special clamping fixtures, the ellipticity of nuts above M36 is controlled within 0.3mm, which is a 50% improvement over the industry average.

5. Summary and Outlook

Handan Guangxuan Fastener Manufacturing Co., Ltd. has established a technological barrier in the field of 8.8-grade carbon steel external hexagon nut manufacturing through the deep integration of material science, precision manufacturing, and quality management. In the future, the company will continue to invest in intelligent equipment, explore new material applications, and provide more reliable connection solutions for the high-end equipment manufacturing industry.