Locking Fasteners
By Staff | March 2008
Spiralock Corp. (Madison Heights, Mich.) has introduced new Drive Notch (DN) wire thread inserts that reportedly show no loss of tension after 24 hours of continuous vibration testing (1 million cycles) and no indication of fatigue problems. Using the Drive Notch installation tool, the inserts simply thread into any NAS 1130, STI (screw thread insert) tapped hole with no need to break off, retrieve or account for tangs — because there are no tangs. DN inserts reportedly eliminate the possibility of loose tangs short-circuiting electronics or causing foreign object damage. It also prevents harm to expensive castings by invasive tang removal techniques. The process of using a Spiralock DN insert is said to be relatively simple: Drill an appropriately sized hole, tap the hole with an STI tap, and install the insert. During installation, the DN installation tool locks into the insert DN to thread the insert into the tapped hole. The insert reportedly eliminate stress in the parent material because there is no staking, key or lock ring necessary to hold it in place. In addition, it resists galling, chemical and environmental corrosion.
