ISO 9001:2015/AS 9100:Rev. D/SBA Certified
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Keensert vs Helicoil
What's the Difference?
An educational comparison of key-locking threaded inserts (Keenserts) and helical wire thread inserts (Helicoil-style), and how the applicable specification determines which is used.
What is the difference between a Keensert and a Helicoil?
Keensert-type products are generally solid threaded inserts that use hardened mechanical locking keys, while Helicoil-type products are wire thread inserts formed from a coiled wire. Both create or restore a strong internal thread; selection between them depends on the engineering application and the governing specification.
How Do They Compare?
Key-locking inserts and helical wire inserts differ in construction, locking method, and installation approach.
Insert construction
Key-locking inserts such as Keenserts are solid, machined bodies. Helical wire inserts are formed from a coiled wire in a diamond-shaped cross-section.
Locking method
Key-locking inserts rely on hardened keys driven into the surrounding parent material after installation. Wire inserts rely on the spring tension of the coiled thread engaging the tapped hole, sometimes combined with a locking coil feature.
Installation approach
Both require a drilled and tapped hole sized for the specific insert. Key-locking inserts are driven in and then have their keys set with broach tooling. Wire inserts are threaded into the hole using an installation tool and, for tanged designs, the installation tang is broken off afterward.
Hole preparation
Each insert type has its own specified drill and tap size and sequence. The two are not interchangeable without re-verifying the applicable installation dimensions for the insert actually being used.
Space requirements
Insert length and outer geometry differ between the two types, which can affect minimum edge distance, wall thickness, and hole depth for a given application.
Repair applications
Both types are used in thread repair applications to restore a damaged or worn threaded hole to a usable thread size, following their own respective installation processes.
Service / removal considerations
Key-locking inserts are mechanically locked in place once the keys are set. Wire inserts can, in some designs, be removed with a specific removal tool. Whether removal is appropriate for either type is an engineering decision specific to the application.
Production considerations
Both insert types can be installed in controlled, repeatable production processes with appropriate tooling, technique, and inspection criteria defined by the governing specification.
Engineering specification requirements
Selection between insert types is governed by the applicable engineering drawing, military or industry specification, or customer requirement, not by general preference.
At a Glance
| Consideration | Keensert / Key-Locking Insert | Helical Wire Insert |
|---|---|---|
| Construction | Solid threaded insert | Formed wire coil |
| Retention approach | Mechanical locking keys | Insert / thread geometry |
| Installation | Requires applicable insert/key installation process | Requires applicable wire-insert installation process |
| Application choice | Engineering / application dependent | Engineering / application dependent |
This comparison is educational. Neither insert type is inherently "stronger" or "better" in every application; the applicable engineering specification determines which is used.
When Might a Key-Locking Insert Be Considered?
Engineers evaluate key-locking inserts such as Keenserts when an application calls for a solid, mechanically locked thread, particularly in lightweight aerospace alloys subject to vibration, repeated fastener cycling, or thread repair. The final decision is governed by the applicable engineering drawing or specification, not by general preference.
When Might a Helical Wire Insert Be Considered?
Engineers evaluate helical wire inserts when an application's design and specification call for a coiled wire insert, which may be preferred in some designs for space, weight, or existing specification requirements. As with key-locking inserts, the governing engineering documentation determines whether this insert type applies.
Can APA Install Key-Locking Inserts?
Yes. American Precision Assembly installs Keenserts and key-locking threaded inserts for aerospace, defense, and high-reliability mechanical assemblies under its AS9100D and ISO 9001:2015 certified quality system. Contact APA to discuss which insert type your engineering documentation specifies.
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Frequently Asked Questions
Not Sure Which Insert Type Applies?
Send us your drawing or specification and our team will confirm the insert type and installation requirements for your application.
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Huntington Beach, CA 92649