Threaded Insert Technical Information

Carr Lane key-locking threaded inserts are ideal for thread reinforcement, especially when the mating stud or bolt will be removed frequently. They provide strong, permanent steel threads in a weaker parent material — ferrous, non-ferrous, or non-metallic. Key Inserts are also well suited for quick repair of stripped, damaged, or worn threads. A solid version is also available to use as a handy plug to relocate holes drilled or tapped on the wrong location. Install with standard drills and taps. Important: Use tap drill specified in table (slightly larger than standard for that thread size). Tap-drill hole tolerance should be -.001/+.004 (-.001/+.005 above .500 dia).

Locking keys are driven down into the parent material during installation, providing a positive mechanical lock against rotation. Inserts with an ID thread 5/16 and above have four locking keys, smaller sizes have two. Pull-out strength can be calculated approximately by the following formula:



Key Inserts are often used to reinforce tapped holes in aluminum tooling plates.




Easy Installation




  • 1. Drill out old threads using tap drill specified in table (Important: Correct tap drill is slightly larger than standard for that thread size).
  • 2. Countersink to diameter shown in table.
  • 3. Tap new threads, using standard tap.
  • 4. Screw in insert until body is slightly (.010 to .030 inches) below the surface, by hand or using installation tool. Keys act as a depth stop.
  • 5. Drive keys down with several light hammer taps on installation tool (or directly on keys if no installation tool is available).



Easy Removal



  • 1. Drill out locking keys with specified drill diameter and depth (see table).
  • 2. Deflect keys inward and break off.
  • 3. Remove insert with an E-Z OUT type tool.
  • 4. Screw replacement into original holes. Parent material is totally undamaged.