What Are Self-Tapping Threaded Inserts and When Should You Use Them?

Self-tapping threaded inserts are specialized fastening components designed to create strong internal threads in materials that are too soft, thin, or fragile to support conventional threading. Unlike inserts that require pre-cut threads, self-tapping inserts cut or form their own threads as they are driven into the base material.

They are commonly used in plastic, wood, aluminum, magnesium, and other low-strength metals where direct tapping would lead to stripped threads or weak joints.

What Exactly Are Self-Tapping Threaded Inserts?

A self-tapping threaded insert typically has:

An internal threaded hole for receiving machine screws or bolts

External cutting edges or flutes that tap threads as the insert is driven in

A knurled, slotted, or cutting design that provides high pull-out resistance

During installation, the insert forms its own mating threads in the host material, locking itself securely in place. This makes it a simple and reliable way to strengthen thread engagement without special tapping operations.

Types of Self-Tapping Threaded Inserts

Common styles include:

1. Cutting Inserts

Use sharp cutting edges to remove material

Ideal for hardwoods, plastics, and thin metals

2. Forming Inserts

Displace material instead of cutting it

Provide stronger thread engagement in plastics

3. Hex-Drive or Torx-Drive Inserts

Allow fast and torque-controlled installation

Useful in automated or production environments

When Should You Use Self-Tapping Threaded Inserts?

You should use self-tapping threaded inserts in the following situations:

1. When the Base Material Is Too Soft for Machine Screws

Examples:

Plastics (ABS, PC, nylon, PP)

Aluminum, magnesium

MDF, plywood, hardwood

Direct tapping in these materials leads to thread stripping. Inserts provide a durable metal thread instead.

2. When You Need High Pull-Out or Torque Strength

Inserts significantly improve:

Pull-out resistance

Torque-out values

Thread wear resistance

This is critical for assemblies that must withstand repeated tightening or vibration.

3. When You Need Repeated Assembly and Disassembly

Soft materials degrade quickly when screws are removed multiple times. Inserts prevent this by offering long-lasting internal threads.

4. When Repairing Stripped Threads

Self-tapping inserts can restore functionality to damaged holes without redesigning or replacing the part.

5. When the Host Material Is Thin

Inserts maximize thread engagement in applications with limited wall thickness.

6. When You Need a High-Quality, Professional Fastening Solution

Industries that frequently use them include:

Electronics enclosures

Automotive components

Aerospace hardware

Furniture fittings

Industrial equipment