Internal-external Thread Insert Manufacturer

What is an Internal-External Thread Insert?

An internal-external thread insert is a special fastener component characterized by having both internal and external threads. This design allows it to function as both an internal threaded sleeve (similar to a traditional expansion sleeve) and a direct connection to an external threaded component, forming a "joint" or "bridge."

Based on their manufacturing process and structural form, internal-external thread inserts are mainly divided into two categories:

1. Wire Thread Insert: Precision-formed from high-strength cold-rolled diamond-shaped stainless steel wire, featuring a concentric structure with coaxial internal and external threads. During installation, the internal thread accepts the insertion of screws or bolts, while the external thread connects to a matching threaded component.

2. Key Locking Insert: Features a locking key or claw (e.g., four claws) on the external thread, achieving strong locking through pressing or welding. This design is primarily used in applications requiring high load capacity and vibration resistance.

These inserts are typically made of highly elastic, corrosion-resistant materials (such as stainless steel or copper alloys) and manufactured using precise stamping or forming processes to ensure a high-precision match between the internal and external threads.

How to Choose the Right Internal-External Thread Insert?

When selecting an internal-external thread insert, it is necessary to comprehensively consider the characteristics of the substrate, the working environment, load requirements, and the specific connection method. The following is a detailed selection guide:

1. Substrate and Strength Matching:

Low-strength substrates (such as aluminum alloys, plastics, and wood): Wire thread inserts are preferred. Because the external thread of the wire thread insert forms an interference fit through pressing or screwing, it can significantly improve the tensile strength and wear resistance of the substrate.

High-strength substrates (such as steel and cast iron): If extremely high connection strength is required or the work is to be performed in a high-temperature environment, key-locking inserts or high-temperature alloy thread inserts can be considered. The latter are made of high-temperature alloy materials and have a temperature resistance range of 500℃-750℃, suitable for extreme conditions such as aero-engines.

2. Load and Strength Requirements:

High-load scenarios: Select inserts with larger outer diameters, prioritizing keyed inserts with locking functions. Claw or deformed thread designs provide additional mechanical locking, preventing loosening due to vibration.

Light loads or precision positioning: Ordinary wire thread inserts are sufficient, offering advantages such as easy installation without significantly increasing part weight.

3. Working Environment and Corrosion Resistance:

Marine or corrosive environments: Stainless steel inserts are strongly recommended, or rust-proofing the external thread surface is essential to prevent corrosion from damaging the connection.

Applications requiring conductivity or self-lubrication: Copper alloy inserts (copper wire thread inserts) can be selected, offering both conductivity and wear resistance.

4. Accuracy and Interchangeability:

High-precision requirements: Regardless of the material chosen, the accuracy of the internal and external threads must meet relevant standards (e.g., GB/T24425.1-2009). These inserts can form standard internal threads conforming to international standards, significantly improving connection reliability and interchangeability.

Dongtai Jinzhize Metal Products Co., Ltd. is a manufacturer specializing in internal and external threaded connectors for the automotive and aerospace industries.

The company boasts a comprehensive product line and technological reserves in the field of internal and external threaded connectors, primarily reflected in the following aspects:

1. Complete Product Range: Dongtai Jinzhize's internal threaded connectors include not only standard Helical Wire Inserts, but also Self-Tapping Inserts and Key Locking Inserts. Key Locking Inserts are a typical example of Internal and External Thread Inserts, offering both external thread connection and internal locking functionality.

2. Focus on High-End Applications: The company's products mainly serve high-end manufacturing industries such as automotive engines, aerospace, and high-speed rail vehicle manufacturing. These industries have extremely high requirements for the strength, fatigue resistance, and precision of threaded fasteners. Dongtai Jinzhize ensures that its Internal-external Thread Insert products meet stringent industrial standards through high-precision stamping processes and a rigorous quality management system.

3. Customization and Assembly Tools: To adapt to different process requirements, Dongtai Jinzhize also provides matching installation taps and tools. This is crucial for the installation of Internal-external Thread Inserts, especially for applications requiring pre-tapping or precision locking.

FAQ

Q: What are the main types?

A: Hot-press inserts (HP): Installed by heating and expanding or contracting, suitable for thinner or easily deformable materials.

Kobsert® inserts: Installed directly using a press or hand tools, fast installation, often used in mass production.

Tap inserts: Installed by directly cutting a hole in the metal using self-tapping threads, simple installation but may weaken the hole wall strength.

Q: Hole machining requirements before installation?

A: Hole diameter: Must be drilled strictly according to standard (e.g., DIN 13) to ensure the hole diameter accuracy meets the insert specifications (usually "Minor Diameter").

Hole depth: The hole depth should meet the requirements of the entire length of the insert, typically 1.5 to 2 times the insert length, to provide sufficient support.

Q: How to install?

A: Tools: Select the appropriate tools (e.g., press, wrench, or hand installer) according to the insert type.

Steps: Place the insert into the drilled hole.

Use a tool to press or screw the insert in until the Safety Flange is flush with the workpiece surface, ensuring the insert is level and secure.

Q: How to remove?

A: Stamped insert: Drill through the safety flange to the external thread, then use a wrench to rotate counterclockwise to remove.

Hot-pressed insert: Requires heating to a specific temperature to expand, or use a special removal tool to remove it in the reverse direction.