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Heli-Coil® vs. Keensert® vs. Keysert® vs. Acme: Comparing Threaded Inserts

Acme Threaded Inserts are often compared to Keensert® inserts and Heli-Coil® inserts. (Keensert is a registered trademark of Huck Patents, Inc., Heli-Coil is a registered trademark of Emhart® Teknologies, Inc). A product similar to Keensert® inserts is the Keysert® insert. Keysert is a registered trademark of Alcoa Fastening Systems (Huck Patents, Inc. is listed as latest owner on US Trademark site.) All of these products are used for thread repair or to bolster the strength of a weaker parent metal, like aluminum.

The largest differences between the inserts are in strength and ease of installation. Heli-Coil® inserts are precision formed thread coils made of stainless steel wire. Installing a Heli-Coil® insert involves tapping (or re-tapping if a thread repair job) a hole, lining up the Heli-Coil® thread with the tapped hole and using a special use tool to install. Cross threading can be a problem if the installer is inexperienced. Heli-Coil® inserts have less pull-out strength than Acme threaded inserts or Keensert®-style products because they are wound wire versus a solid metal bushing.

Both Acme Threaded Inserts and Keensert®-style inserts are easy to install with standard drills and taps. The inserts are placed by the installer's fingers, without the need of a pre-winder tool. Accidental cross-threading is nearly impossible.

When an Acme or Keensert®-style insert needs to be removed, the material between the keys is drilled out with a standard drill, the keys are bent inward to break off, and a standard screw extractor is used. If a removed insert needs to be replaced, the new insert can be placed into the original tapped hole.

Acme Threaded Inserts have some advantages over similar Keensert® inserts:

  Acme Threaded Inserts Keensert® Inserts Heli-Coil® Inserts
Special Installation Tools Required? No, Standard Drills and Taps are Used No, Standard Drills and Taps are Used Yes, Special Purpose Drills, Taps and Pre-Winder Tool Needed
Easy to Install? Yes Yes Takes Some Practice
Avoids Potential Tang Break Off Issues? Yes Yes No
Superior Pullout Strength from Solid Bushing and Locking Key? Yes Yes No
Positive Mechanical Lock to Prohibit Rotation? Yes Yes No
Difficult to Cross Thread by MIstake During Installation? Yes Yes No
Used in Nearly Any Base Material(Aluminum, Magnesium, Plastics, Steel, Cast Iron)? Yes Yes ?
Easy to Remove? Yes Yes Yes
New Insert can be Used in Same Hole After Removal of Previous Insert? Yes Yes Yes
Solid Carbon Steel Inserts Available? Yes No No
Solid Metric Inserts have Both Internal and External Metric Threads? Yes No NA
Greater Variety of Solid Insert Kit Styles? Yes No NA
Greater Number of Solid Insert Metric Sizes? Yes No NA
Made in U.S.A.? Yes ? ?
DFARS-Compliant? Yes ? ?

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Aerospace Industries