Distinguish the two interfaces
Confirm external retention and internal screw locking separately.
SELF-LOCKING KEY INSERT
Screw-Locking Key Inserts
Two locking interfaces. Two distinct functions.
External keys restrain the insert; internal locking geometry acts on the mating screw. Understanding both functions determines the validation method.
DESIGNED FOR CONNECTION
Secure the insert. Consider the screw.
Screw-locking key inserts combine external locking keys with an internal screw-locking feature. The keys resist rotation relative to the parent material; the internal feature resists screw rotation. Refer to the selected model's drawing for its internal geometry.
Integrated design
Consider screw locking within a solid insert.
Independent quality inspection
Inspect installation position separately from locking performance.
01 / STRUCTURE
Start with the right structure.
The insert structure determines how screw-locking key inserts connect and install.
Locking type
Confirm insert anti-rotation and internal screw-locking requirements separately.
Custom type
Confirm the structure for the available material space and maintenance needs.
Related product:Explore the related product →
02 / MATERIAL
Match the material to the conditions.
These material options are discussion points; not every model is available in every combination.
Stainless steel
Confirm grade, strength and corrosion resistance against the supply drawing.
Other materials
Discuss the parent material, environment and connection loads.
Material documentation
Specify the material standard and required inspection documents in the order.
03 / SURFACE
The finish is part of the connection.
Consider friction, corrosion resistance and identification in the operating environment. Confirm available combinations with an engineer.
Surface condition
Confirm whether lubrication, protection or another treatment is needed.
Mating compatibility
Check the combination of parent material, screw, media and surface treatments.
Made to drawing
Include treatment type and thickness in dimensional and acceptance requirements.
INSTALLATION
From preparation to final inspection.
Confirm the screw combination
Specify screw finish, lubrication and torque requirements.
Install and position
Install the solid insert according to the approved process.
Key installation
Complete the mechanical lock between insert and parent material.
Check both functions
Inspect the locking keys and screw-locking performance separately.
The rendering illustrates the key-insert family, not a section view or inspection reference for the locking internal thread.
CONFIGURATION
Bring your requirements to our engineers.
Choose a preferred configuration and add thread size and operating conditions. This is an engineering enquiry, not a confirmed supply configuration.
Confirm these details for a clearer discussion.
Internal locking design
Confirm from the drawing, not the model name alone.
Mating screw
Material, finish, lubrication and strength requirements.
Acceptance method
Define installation checks and locking-torque checks.
Maintenance requirements
Disassembly frequency and permitted replacement procedure.
KEY-LOCKING INSERTS · DRILL & TAP
Key-locking insert drill & tap data.
Choose the lightweight or heavy-duty series, then match the internal thread, external thread and installation hole.
Metric reference edition: 28 installation combinations. Standard and locking versions share the listed installation fields. Compatibility with ZCOIL products is unverified; approved drawings govern machining. Not for wire inserts.
Metric lightweight mm · Standard / locking
The tap matches the external thread, class 6H. Listed depth is minimum tapping depth, not total drilling depth.
Download CSV (opens in Excel) ↓| Internal thread | External thread | Length L +/-0.3 | Tap drill Ø | Countersink Ø +0.25/-0.00 | Installation tap 6H | Min tapping depth |
|---|---|---|---|---|---|---|
| M5X0.8 | M8X1.25 | 8.0 | 6.9 | 8.25 | M8X1.25 | 9.5 |
| M6X1.0 | M10X1.25 | 10.0 | 8.8 | 10.25 | M10X1.25 | 11.5 |
| M8X1.25 | M12X1.25 | 12.0 | 10.8 | 12.25 | M12X1.25 | 13.5 |
| M8X1.0 | M12X1.25 | 12.0 | 10.8 | 12.25 | M12X1.25 | 13.5 |
| M10X1.5 | M14X1.5 | 14.0 | 12.8 | 14.25 | M14X1.5 | 15.5 |
| M10X1.25 | M14X1.5 | 14.0 | 12.8 | 14.25 | M14X1.5 | 15.5 |
| M12X1.75 | M16X1.5 | 16.0 | 14.75 | 16.25 | M16X1.5 | 17.5 |
| M12X1.25 | M16X1.5 | 16.0 | 14.75 | 16.25 | M16X1.5 | 17.5 |
Metric heavy-duty mm · Standard / locking
The tap matches the external thread, class 6H. Listed depth is minimum tapping depth, not total drilling depth.
Download CSV (opens in Excel) ↓| Internal thread | External thread | Length L +/-0.3 | Tap drill Ø | Countersink Ø +0.25/-0.00 | Installation tap 6H | Min tapping depth |
|---|---|---|---|---|---|---|
| M4X0.7 | M8X1.25 | 8.0 | 6.9 | 8.25 | M8X1.25 | 9.5 |
| M5X0.8 | M10X1.25 | 10.0 | 8.8 | 10.25 | M10X1.25 | 12.5 |
| M6X1.0 | M12X1.25 | 12.0 | 10.8 | 12.25 | M12X1.25 | 14.5 |
| M8X1.25 | M14X1.5 | 14.0 | 12.8 | 14.25 | M14X1.5 | 16.5 |
| M8X1.0 | M14X1.5 | 14.0 | 12.8 | 14.25 | M14X1.5 | 16.5 |
| M10X1.5 | M16X1.5 | 16.0 | 14.75 | 16.25 | M16X1.5 | 18.5 |
| M10X1.25 | M16X1.5 | 16.0 | 14.75 | 16.25 | M16X1.5 | 18.5 |
| M12X1.75 | M18X1.5 | 18.0 | 16.75 | 18.25 | M18X1.5 | 20.5 |
| M12X1.5 | M18X1.5 | 18.0 | 16.75 | 18.25 | M18X1.5 | 20.5 |
| M12X1.25 | M18X1.5 | 18.0 | 16.75 | 18.25 | M18X1.5 | 20.5 |
| M14X2.0 | M20X1.5 | 20.0 | 18.75 | 20.25 | M20X1.5 | 22.5 |
| M14X1.5 | M20X1.5 | 20.0 | 18.75 | 20.25 | M20X1.5 | 22.5 |
| M16X2.0 | M22X1.5 | 22.0 | 20.50 | 22.25 | M22X1.5 | 24.5 |
| M16X1.5 | M22X1.5 | 22.0 | 20.50 | 22.25 | M22X1.5 | 24.5 |
| M18X1.5 | M24X1.5 | 24.0 | 22.50 | 24.25 | M24X1.5 | 26.5 |
| M20X2.5 | M30X2.0 | 30.0 | 28.00 | 30.25 | M30X2.0 | 34.5 |
| M20X1.5 | M30X2.0 | 30.0 | 28.00 | 30.25 | M30X2.0 | 34.5 |
| M22X1.5 | M32X2.0 | 32.0 | 30.00 | 32.25 | M32X2.0 | 36.5 |
| M24X3.0 | M33X2.0 | 33.0 | 31.00 | 33.25 | M33X2.0 | 37.5 |
| M24X2.0 | M33X2.0 | 33.0 | 31.00 | 33.25 | M33X2.0 | 37.5 |
Reading notes and applicability
- Metric key-locking insert installation references, in mm. Lightweight and heavy-duty series are separate: the same internal thread may need different external threads and hole sizes.
- The installation tap matches the external thread; the tapped hole is class 6H. Do not use wire-insert STI data or tap to the insert internal thread. Confirm the insert, material, tooling and drawing.
- L tolerance: +/-0.3 mm. Countersink diameter: +0.25 / -0.00 mm. Minimum tapping depth is not total drilling depth. Allow separately for drill point, tap lead and blind-hole clearance; drill tolerance and countersink angle follow the approved drawing.
- Standard and locking variants share the listed installation fields in the source, so these fields are combined. Locking geometry, locking-zone length, load and torque are excluded; interchangeability is not implied.
- Coverage: 8 lightweight and 20 heavy-duty metric combinations. Unlisted sizes, inch series and other families are not extrapolated. Listed dimensions do not establish ZCOIL supply availability.
- Installation drilling and removal drilling serve different purposes. Only installation fields are included here. Confirm key-slot preparation and installation requirements for hard parent materials.
- ZC-KL-20261001-R1. Reorganized from a public official catalogue. ZCOIL product compatibility is not verified. Approved drawings govern machining.
ZC-KL-20261001-R1 · Dimensions in mm · unlisted sizes are not extrapolated
KNOWLEDGE & RESOURCES
Explore further.
Frequently asked questions
Can a standard key-locking insert replace it?
Free-running and screw-locking internal threads have different functions. Reassess the connection requirements before substituting one for the other.
Should the screw still be checked after the keys are driven?
Yes. Correct key installation does not prove that internal locking performance meets requirements.