Partial Threaded Flange Bolts

In heavy machinery, steel structure connections, equipment assembly, and other applications, fasteners not only need to withstand high-strength connection loads but also often require precise positioning capabilities. In these scenarios, fully threaded bolts are prone to deformation due to uneven stress distribution on the threads, or may affect assembly accuracy due to their inability to precisely fit the positioning surface, thus impacting equipment operational stability and service life. This is especially critical in heavy-load and vibration conditions, where the requirements for bolt load-bearing capacity and positioning reliability are even more stringent.

We are a source factory with over 20 years of experience in fastener research, development, and manufacturing, deeply rooted in the industry for many years, and accurately understanding the connection needs under different working conditions.

Core Technological Advantages

1. Semi-threaded structure design for superior tensile and shear performance

The Partial Threaded Flange Bolts shank is divided into a smooth shank and a threaded section. The core advantage lies in the absence of stress concentration points caused by thread cutting in the smooth shank area. This design gives the bolt superior strength and longer service life when subjected to large tensile forces or alternating loads, perfectly suited for heavy-load scenarios requiring high tensile strength.

When connecting two thick plates or bearing lateral shear forces, the smooth shank effectively resists shear deformation, preventing bolt fracture or loosening of the connecting parts. Its shear resistance far exceeds that of fully threaded bolts, making it a key solution for connection problems in high-shear force conditions.

The diameter of the smooth shank is usually larger than the thread pitch diameter, providing a more stable support surface and ensuring that the preload remains constant. During assembly, the smooth shank also allows for precise positioning, improving the assembly accuracy of the connection and ensuring equipment operational stability.

2. Integrated flange face for double protection against loosening

The flange and bolt head are integrally formed, with a precision serrated structure on the edge. When tightened, the serrations firmly grip the connecting surface, generating strong frictional resistance and fundamentally preventing bolt loosening caused by equipment vibration, resulting in significant anti-loosening and anti-vibration effects. The flange surface increases the bearing area between the bolt and the workpiece, evenly distributing the load and effectively preventing the Partial Threaded Flange Bolts head from embedding into soft materials such as aluminum, plastic, and wood. This protects the integrity of the workpiece surface and enhances the overall stability of the connection, eliminating the need for additional washers and simplifying the assembly process.

3. High-quality base materials and precision manufacturing lay the foundation for quality.

Selected high-quality alloy steel wire rods such as medium carbon steel, 40Cr, and 35CrMo are used. Each batch of raw materials comes with a material certificate, and spectral analysis is performed before warehousing to accurately control the chemical composition, eliminating material defects from the source and meeting different strength grade requirements.

Using advanced cold heading forming technology, the bolt head and flange are formed in one piece. The metal flow lines are continuous, and the internal structure is dense, resulting in significantly higher strength than machining.  Combined with precision thread rolling technology, the thread accuracy meets standards, the thread profile is full, and the engagement is smooth, ensuring convenient assembly and reliable connection.

Core Technical Parameters

Typical Application Scenarios

With over 15 years of industry experience, our partially threaded flange bolts have been successfully adapted to numerous demanding application scenarios, becoming the trusted choice for thousands of companies worldwide:

1. Automotive and Transportation: Suitable for core components such as engine cylinder heads, connecting rods, wheels, and chassis suspension systems. These parts are subjected to immense explosive forces and continuous vibrations, and the partially threaded design provides ultimate safety, ensuring driving stability.

2. Mechanical Equipment: Used for connections in gearboxes, pumps and valves, molds, motor end caps, etc. The unthreaded portion allows for precise component positioning while effectively resisting shear forces, ensuring stable connections during continuous operation and reducing maintenance downtime.

3. Steel Structure Engineering: Suitable for heavy-duty steel structure connections, bridge components, tower and mast structures, etc. The partially threaded design offers excellent fatigue resistance, ensuring the long-term stability of building structures and meeting the quality requirements for projects designed to last for a century.

4. Industrial Manufacturing: Used for body connections in large hydraulic presses, injection molding machines, etc.  It can withstand the high loads during equipment operation, ensuring the stability of the machine structure and guaranteeing smooth production.

Company Strength and Quality Assurance

We are Ningbo Gangtong Zheli Fasteners Co., Ltd., established in 2001.  Since then, we have built a mature R&D, production, and sales system for fasteners. Our factory is located in the Zhenhai Chemical Industrial Zone in Ningbo, and our headquarters and foreign trade sales department are located in the Ningbo Jiangdong Eastern Business Center. The factory covers an area of 15,000 square meters, with a stable monthly production capacity of 2,000 tons and annual sales exceeding US$15 million. The company is equipped with a professional R&D team, a full-process supply chain management system, and large-scale warehousing facilities, providing integrated MRO procurement and distribution services for metal fasteners to fully meet diverse customer needs.

In the field of high-strength fasteners, quality is paramount. We have established a rigorous quality control system throughout the entire process to ensure the reliability of every bolt: strict material selection, using only high-quality wire rods that meet national/American/German standards, with material certificates for each batch; comprehensive process control, from spectroscopic analysis of raw materials upon arrival, to full inspection of hardness and tensile strength during the production process, and finally to salt spray testing of finished products – no detail is overlooked; complete certifications, fully implementing the ISO 9001 quality management system standard, and products are CE certified, meeting international export requirements. Each batch of products has a unique quality assurance certificate (MTC), traceable to the raw material furnace number and heat treatment batch, giving customers peace of mind.

Our product range is extensive, including Partial Threaded Flange Bolts, as well as heavy-duty hex bolts, heavy-duty hex nuts, threaded rods, studs, washers, etc., in materials including carbon steel, alloy steel, and stainless steel. We strictly adhere to international standards such as DIN, ISO, EN, JIS, ASTM/ANSI/ASME/SAE, BS, and AS. Our products are exported to North America, Europe, Australia, Southeast Asia, the Middle East, Latin America, and other regions, and are suitable for various fields such as building steel structures, bridges, oil pipelines, mechanical equipment, ships, and railways.

Reasons to Choose Us

1. Direct supply from the source factory, outstanding cost-effectiveness: As a physical manufacturer in China's fastener industry cluster, we have advanced cold heading, heat treatment, and thread rolling equipment, achieving independent production throughout the entire process from raw materials to finished products. Without intermediaries, we can offer highly competitive factory prices, and we have ample stock of standard specifications to ensure fast delivery.

2. Professional technical support and precise customized services: Our experienced engineering team can provide professional non-standard customization (OEM/ODM) services based on drawings or samples provided by customers. We can quickly respond to and provide solutions for technical problems encountered by customers during use, helping to solve challenging connection issues.

3. Efficient delivery guarantee, making cooperation more worry-free: We have a complete inventory system and an efficient logistics network, providing free samples for customer testing and verification. We offer quick response for small batch orders and high on-time delivery rates for large batch orders, ensuring that we never delay our customers' production schedules.