Helical Insert vs. Key-Locking Insert
Both repair stripped threads, but one is a compact coil and the other a solid locked bushing.
| Feature | Helical Insert (Heli-Coil) | Key-Locking Insert (Keensert) |
|---|---|---|
| Form | Coiled wire | Solid bushing with keys |
| Strength in soft metals | Good | Excellent |
| Space needed | Minimal (small drill + tap) | Larger hole + counterbore |
| Locking | Friction (can unwind if misused) | Positive key locking |
| Cost | Lower | Higher |
Verdict
Use a helical insert for standard thread repair where space is tight. Use a key-locking insert for high-load threads in soft parent materials like aluminum castings.