Helical Inserts

Helical Inserts

In modern manufacturing, threaded connections are one of the most common and fundamental assembly methods. From aerospace to automotive manufacturing, as well as electronic equipment and industrial machinery, almost all structural components rely on threads. However, in practical applications, many companies have gradually found that threads formed directly by tapping often cannot meet the requirements of high strength and high-frequency use.

As a result, a seemingly simple yet critical technology— helical inserts is being widely adopted across more and more industries.

What is a Wire Thread Insert?

A wire thread insert is a new type of internal threaded fastener. It is made by winding a corrosion-resistant, diamond-shaped cross-section steel wire with high strength, high precision, and high surface quality into a spring-like form.

After being installed into a threaded hole, the outer surface of the insert fits tightly against the hole wall through elastic force, while the inner surface forms a new internal thread. This allows screws or bolts to be fastened without directly contacting the base material, thereby protecting both the base material and the fastener.

It effectively extends thread service life, increases thread connection strength, enlarges the load-bearing surface, and improves load capacity, fatigue resistance, vibration resistance, and anti-loosening performance.

Why Install Wire Thread Inserts?

1.Improve Thread Strength in Low-Strength Materials

In materials such as aluminum alloys, copper alloys, or engineering plastics, threads formed by direct tapping have limited strength:

• Prone to stripping
• Low tensile strength
• Easy to fail after long-term use

Wire thread inserts, typically made of stainless steel, can significantly improve:

• Tensile strength of threads
• Shear strength
• Overall connection stability

2.Extend Thread Service Life

In applications requiring frequent assembly and disassembly (such as equipment maintenance and modular structures):

• Conventional threads wear out over time
• Repeated tightening can lead to loosening or even failure

Wire thread inserts offer excellent wear resistance, significantly extending service life and maintaining stable performance over long-term use.

3.Thread Repair and Size Restoration

When threads are damaged due to machining errors or usage, the traditional solution is to enlarge the hole and re-tap it, which changes the original design and affects assembly.

With wire thread inserts:

• The original thread specification can be maintained
• Damaged threaded holes can be quickly repaired
• Even oversized threaded holes can be restored to proper size
• This effectively reduces scrap rates and lowers costs.

4.Optimize Connections Between Different Materials

In combinations like “steel screw + aluminum part”:Aluminum threads are easily damaged by steel fasteners.

With wire thread inserts:The contact becomes “steel-to-steel”.

Wear caused by material mismatch is effectively avoided.

5.Vibration Resistance and Anti-Loosening

Locking-type inserts feature a special structure that can firmly lock screws within threaded holes under strong vibration and impact conditions, preventing loosening. Their locking performance is superior to many other locking methods.

6.Wear Resistance, Heat Resistance, and Corrosion Resistance

Due to the high surface finish of wire thread inserts, friction between internal and external threads is greatly reduced. The material itself also provides excellent resistance to high temperatures and corrosion.

7.Anti-Seizure (Prevention of Thread Galling)

Thanks to the material properties and smooth surface, wire thread inserts prevent seizure even in humid or corrosive environments. This avoids costly replacement of base materials due to stuck threads.

8.Thread Conversion

Wire thread inserts can also be used to convert between different thread systems, such as:

Metric ↔ Imperial

Metric ↔ Unified threads

Types of Wire Thread Inserts

1.Free-Running Inserts

Inserts with tang (break-off notch)

Inserts without tang

2.Locking Inserts

Locking inserts have one or several coils shaped into a polygon. After installation, they not only rely on elastic force to stay in place but also use friction between the polygonal section and the mating screw threads to achieve a locking effect.

Specification Meaning

Example: M6-1 × 1.5D

M6: Thread size is M6

-1: Pitch is 1 mm

1.5D:

D = nominal thread diameter (M6 = 6 mm)

1.5D = 1.5 × 6 = 9 mm (insert length)