A helical thread insert is a coil of stainless steel wire with a diamond-shaped cross-section. Once installed in the parent material it forms an internal thread more durable than the parent material itself. Two typical uses: (1) soft materials such as aluminum, cast iron and plastic that must be assembled and disassembled repeatedly; (2) repairing a stripped thread back to its original size — enlarge the hole, tap it with the dedicated tap and install the insert; the thread it presents is still the original M size, so the drawing does not need to change.
Written as thread size × length multiple, e.g. M8-P1.25*1.5D. D is a multiple of the thread diameter: 1D means the length equals one thread diameter; we regularly stock 1D / 1.5D / 2D / 2.5D / 3D. For ordinary steel 1D-1.5D is sufficient; for soft materials such as aluminum or plastic, 2D or more is recommended to spread the stress. Fine-thread items show the P pitch.
| Step | Tool | Key point |
|---|---|---|
| 1. Drill | Drill for the corresponding tap drill size | The hole is larger than the original thread; size as specified for the insert |
| 2. Tap | Dedicated insert tap | The thread form differs from a standard tap; a standard tap cannot be used instead |
| 3. Install | Insert installation tool | Screw in until about half a thread below the hole surface |
| 4. Break off the tang | Tang break-off tool | Break off and remove the driving tang so it does not jam the screw |
If an insert is installed incorrectly or needs replacing, remove it with an insert extraction tool. The common corresponding standard is DIN 8140; self-locking inserts (with a gripping coil section) are also available and need no extra locking parts — state it in your inquiry if needed.
Click a size to open its product page (price and stock status); lists update automatically with our stock.