What Is a Wire Thread Insert and When Do You Need One?

You're bolting into an aluminum housing. After a few assemblies, the threads strip out — this is the classic problem with soft materials. Wire thread inserts were invented to solve exactly this.

What Is a Wire Thread Insert?

A wire thread insert is a precision diamond-profile stainless steel wire (typically 304 or Inconel X-750) cold-wound into a spring-like helical coil. Installation: drill a pilot hole, tap with a special tap, screw in the insert with an installation tool, then break off the tang. The external threads lock into the parent material; the internal threads become a standard bolt hole.

When You Must Use One

1. Threads in soft materials. Aluminum, magnesium, and zinc alloys have 1/3 to 1/2 the shear strength of steel. If the design requires the bolt to fracture before threads strip, aluminum engagement length needs 2× diameter. When wall thickness doesn't allow it, a wire insert is the answer.

2. Repeated disassembly. Aluminum threads wear out after a few assemblies. The stainless internal threads of a wire insert survive 50+ assemblies.

3. Thread repair. When threads strip, over-tapping to a larger size may require changing mating parts. A wire insert lets you keep the original bolt size.

4. High temperature or corrosion. Inconel X-750 inserts survive above 425°C where aluminum threads lose strength.

Selection Tips

• Standard vs. locking: locking inserts have one polygonal coil for prevailing torque
• Length: 1d, 1.5d, 2d (d = bolt diameter). Use 1.5d or 2d for aluminum
• Material: 304 stainless standard, Inconel X-750 for high temp, 316 for corrosion
• Always use the special installation tool — don't screw it in with a screwdriver

Toprecision supplies wire thread inserts, installation tools, and hole-size calculations.