Locking fasteners
By Staff | April 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. Aided by the Drive Notch installation tool, the inserts simply thread into any NAS 1130, STI (screw thread insert) tapped hole with no tangs to break off, retrieve or account for — DN inserts, therefore, eliminate the possibility that a loose tang could short-circuit electronics or cause foreign object damage. It also prevents harm to expensive castings that can result form invasive tang removal techniques. The process of using the inserts is said to be relatively simple: Users 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 eliminates 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 and chemical and environmental corrosion.
