I. Company Background and Technical Strength Overview

Handan Guangxuan Fastener Manufacturing Co., Ltd. is located in the Yongnian Standard Fastener Industrial Base of Hebei Province, benefiting from the three-dimensional transportation network composed of the Jingguang Railway, National Highway 107, the Beijing-Hong Kong-Macau Expressway, and Qinghong Expressway, achieving efficient national logistics coverage. As one of the earlier established fastener manufacturing entities in the local area, the company specializes in customized processing, mainly producing tower crane bolts, high-strength bolts, double-end bolts, and 8.8-grade carbon steel external hexagonal nuts, among other standard and non-standard parts. Its annual production capacity reaches tens of thousands of tons, and its technical strength ranks among the forefront of the industry.

Section 2, 8.8 Grade Carbon Steel External Hex Nuts Technical Parameters and Application Scenarios

Grade 8.8 carbon steel external hexagonal nuts are made from medium carbon steel (such as 35#, 45# steel) after quenching and tempering treatment, with tensile strength ≥800MPa, yield strength ≥640MPa, and hardness range HRC22-32. They are suitable for high-connection-strength scenarios such as machinery manufacturing, building structures, bridge engineering, etc. Their standard specifications range from M6 to M64, with thread accuracy in accordance with GB/T 197-2018. Surface treatments available include blackening, galvanizing, and Dacromet, meeting different environmental anti-corrosion requirements.

3. Customized Production Process and Quality Control System

STEP 1: Raw Material Inspection and Pretreatment
After raw materials enter the factory, they must be tested by a spectrometer to ensure chemical composition, with carbon content of 0.32%-0.45% and manganese content of 0.60%-0.90%. Meanwhile, tensile tests are conducted to verify mechanical properties. The pretreatment stage uses a continuous belt furnace for spheroidizing annealing to eliminate internal stress and improve cutting performance.

Step 2: Cold Forging and Thread Machining
The nut blanks are formed in one go using a multi-station high-speed cold heading machine, with a single piece production cycle of ≤0.5 seconds and material utilization of over 95%. Thread processing is carried out with a CNC rolling thread machine, controlled by three-axis linkage to ensure the pitch accuracy, guaranteeing thread fitment grade up to 6g.

STEP 3: Heat Treatment and Surface Treatment
Quenching treatment is carried out in a well-type resistance furnace, with a heating temperature of 850±10°C, holding time calculated at 2.5 minutes/mm of effective thickness, quenching medium is rapid oil, and tempering temperature is 450±10°C. Surface treatment is completed through an automated production line, with salt spray test reaching 720 hours without white rust.

4. Technical Case: Customized Nuts Practice in a Wind Power Project

In 2023, the company customized M48×150mm 8.8-grade carbon steel nuts for a wind power project in Inner Mongolia, which needed to meet the requirement of impact work at -40℃≥27J. The technical team achieved this by optimizing alloy composition (adding 0.2% nickel element), adjusting heat treatment process (using分级 quenching), and increasing low-temperature tempering process. The final product passed SGS third-party testing and was successfully applied in the tower connections of 30 2.5MW wind turbine generators, with over 5,000 pieces used cumulatively, without any failure due to breakage.

V. Summary of Technical Advantages and Industry Application Experience

Guangxuan Fasteners achieves a shortened customized order delivery cycle to 7 days, with product pass rate consistently over 99.8%, through full-process digital control (introducing ERP+MES systems), equipment automation upgrade (cold heading machine precision up to ±0.01mm), and quality traceability system (each batch of products bound with a unique code). Its technical layout covers material research and development, process optimization, and detection capability enhancement, having served over 200 equipment manufacturing enterprises, customizing over 100,000 non-standard parts in total, forming a dual-drive model of "standard parts rapid supply + non-standard parts deep customization."

Structured FAQ Page

Q1: What is the main difference between 8.8 grade and 10.9 grade nuts?
A: Grade 8.8 nuts have a tensile strength ≥800MPa, suitable for general mechanical connections; Grade 10.9 nuts have a tensile strength ≥1040MPa, require alloy steel manufacturing, mainly used in high-load scenarios such as automotive suspension systems.

Q2: How to determine if the nut quality meets the standard?
A: Inspection via three points: ①No cracks or burrs on the surface; ②Hardness value measured by hardness tester; ③Torque tester to verify failure torque (M12 nut standard value ≥115N·m).

Q3: What is the minimum order quantity for non-standard customization?
A: Standard specification non-standard parts have a minimum order quantity of 5,000 pieces, complex non-standard parts have a minimum order quantity of 2,000 pieces, and the specific quantity depends on the product structure for mold cost evaluation.