Key Locking Inserts (Keensert-Type) for Heavy-Duty Threads
Solid one-piece inserts locked by driving keys — maximum torque, pull-out and vibration resistance in aluminum and steel. Miniature to ultra-heavy duty; inch, metric and MS-series sizes in 303 stainless stock.
A key locking insert is a solid, one-piece threaded bushing with two or four driving keys. After the insert is screwed into a tapped hole, the keys are driven down into the parent thread, mechanically locking the insert against rotation and pull-out. It is the heavy-duty answer wherever coil inserts reach their limits — high torque, high vibration, high temperature.
What Is a Key Locking Insert?
“Keensert” is a registered trademark; the generic category is the key locking insert. The body is a solid bushing with internal and external threads — no coil flex, full metal engagement. The keys protrude from the top of the outer thread; after installation they are hammered or pressed into the parent material’s threads, wedging the insert so it cannot rotate or back out.
How the Key Lock Works
Friction-based locking (adhesives, nylon patches) decays with temperature and cycles. Key locking is mechanical: the driven keys deform into the parent thread flanks and hold regardless of heat, oil or vibration. That is why military, rail, mining and heavy-drive specifications name key locking inserts explicitly.
Where They Excel vs Coil Inserts
Wire thread inserts distribute load beautifully in soft alloys — but extreme bolt torque can set the coil turning. Key locking inserts take the full torque a bolt can deliver, and their solid wall bridges marginally worn parent threads. Use coils for strength-to-weight; use keys for brute duty.
Product Range: Four Duty Classes
| Class | Wall / Keys | Typical Use |
|---|---|---|
| Miniature | Compact body, 2 keys | Small assemblies where solid threads still matter |
| Light duty | Thin wall, 2 keys | Aluminum housings, general vibration service |
| Heavy duty | Thick wall, 4 keys | High torque, rail and heavy machinery |
| Ultra-heavy duty | Maximum wall, 4 keys | Military drives, mining equipment, extreme pull-out loads |
Materials: 303 stainless (US MS-series sizes stocked in 303) and carbon steel (phosphate-finished); locking-pin variants available. Metric and inch threads both stocked.
Installation Data (Examples)
| Class | Internal Thread | External Thread | Overall Length | Drill Ø |
|---|---|---|---|---|
| Light duty | M5×0.8 (6H) | M8×1.25 (6g) | 8 mm | 6.9 mm |
| Heavy duty | M10×1.5 | M16×1.5 | 16 mm | 12.8 mm |
Full dimension tables per class and size are available on request — drill, tap and counterbore values aligned in one sheet for process planning. Matching taps and key-driving tools are listed under installation tools.
Repair Stripped Threads with Key Locking Inserts
A stripped hole in an expensive housing does not need a bigger bolt. Drill out, tap for the insert’s outer thread, screw in the key locking insert and drive the keys: the original internal thread is restored at full strength — usually stronger than the parent thread ever was. This makes key locking inserts a standard item in thread repair kits for gearboxes, engine blocks and machine frames.
Key Locking Inserts in Liquid-Cooled Server Chassis
Liquid-cooled server chassis in aluminum faced a compound threat: continuous high-power vibration plus thermal cycling, with repeated maintenance disassembly wearing parent threads — and a loose insert near a coolant line means leak risk and downtime. Ankolam supplied stainless key locking inserts with the mechanical double-lock: after the bushing is seated, the driven keys lock it against rotation and pull-out. Result: zero insert rotation or back-out under vibration and thermal cycling, threads survive repeated maintenance disassembly with 10× longer thread life, protecting continuous data center operation.
Key Locking Insert FAQ
Are Ankolam key locking inserts interchangeable with Keensert-type brands?
Yes — miniature, light, heavy and ultra-heavy duty classes follow the international dimension conventions, so they fit the same tapped holes and keys seats. MS-series inch sizes are stocked in 303 stainless.
Do I need special tooling?
A tap for the outer thread, a screwdriver or installation tool to seat the insert, and a key-driving (peening) tool to set the keys. See installation tools.
Key locking vs screw-locking wire inserts — which for high vibration?
Screw-locking coils grip the bolt against loosening; key locking inserts lock the insert itself into the parent thread. For extreme torque, pull-out or temperature, choose keys; for lightweight load distribution with bolt retention, choose locking coils.
What is stocked for fast delivery?
Common MS-series inch sizes in 303 stainless and standard metric sizes ship from semi-finished stock; specials quoted per drawing.
Request a Key Locking Insert Quote
Send thread spec, duty class and quantity — engineering confirmation within one business day, samples before volume.