New Spiralock Drive Notch™ Wire Inserts: All the Benefits of Spiralock with No Tangs to Remove

Engineers seeking added joint strength in softer materials like aluminum have long used wire inserts. They've had a streamlined, “no tang” installation option, but never been able to combine these benefits with the vibration loosening resistance, even load distribution, reusability, and decreased galling of Spiralock.

Now they can with Spiralock's new Drive Notch Wire Inserts (DN™). Independent tests prove that bolts installed into these new inserts have shown no loss of tension after 24 hours of continuous vibration testing (one million cycles) and no indication of fatigue problems.

Unlike tanged wire inserts, which require breaking off, retrieving and accounting for tangs, the DN™ Wire Inserts require no such extra steps. Using the Drive Notch installation tool, the inserts simply thread into any NAS 1130, STI tapped hole with no need to break off, retrieve or account for tangs — because there are no tangs. This speeds installation and improves quality, reducing costs on multiple fronts. DN™ inserts eliminate the possibility of loose tangs short-circuiting electronics or causing foreign object damage. They also prevent harm to expensive castings by invasive tang removal techniques. DN™'s space and weight advantage over solid bushing type inserts allow them to be designed into reduced diameter bosses and flanges, and into hard to reach areas.

Whether specified from the start, for repair or retrofit, the process of using is straightforward: drill an appropriate sized hole, tap the hole with an STI tap, and install the insert. During installation, the Drive Notch installation tool locks into the insert Driving Notch to thread the insert into the tapped hole.

Unlike a traditional wire insert using a 60-degree thread design susceptible to self-loosening rotational movement, stripping and shearing, the Spiralock Drive Notch Wire Inserts use Spiralock's patented 30-degree "wedge" ramp formed into a unique 5-sided wire. When wound into a coil shape, it creates the ramp at the root of the female thread. Under clamp load, the crests of the threads on any standard male bolt are drawn tightly against the wedge ramp. This eliminates sideways motion that causes vibrational loosening and distributes the threaded joint’s load throughout all engaged threads, a claim supported by a Massachusetts Institute of Technology research study.

Through its superior resistance to shock, vibration, and thermal extremes, the Drive Notch Wire Inserts offer improved joint integrity in softer materials such as aluminum, zinc, magnesium and plastic. are not passivated (except by customer choice) so the stainless steel remains active for better galvanic compatibility with aluminum and magnesium parent materials. They are also available with a variety of optional coatings and platings.

Since Drive Notch Wire Inserts eliminate stress in the parent material there's no staking, keys or lock rings necessary to hold them in place. As they resist galling, chemical and environmental corrosion, they can be particularly effective in industries such as aerospace, automotive, electronics, and medical.


For more info on Spiralock Corp. technology and products, visit www.spiralock.com; email slinfo@spiralock.com; call (800) 521-2688; fax (248) 543-1403; or write to them at Madison Tech Center, PO Box 71629, Madison Heights, MI 48071.