Self Locking Threaded Fasteners: Michigan Company Celebrates its 80th Anniversary

As Spiralock Corporation of Madison Heights, Michigan (www.spiralock.com) celebrates its 80th anniversary this year, its self locking threaded fasteners are increasingly a solution for today's critical engineering applications requiring ever lighter, stronger, higher speed, vibration and temperature designs.

Starting out as Michigan Tool Company in 1927 with screw thread engineering expertise, the company grew and evolved with time, teaming up in the later years with inventor Horace Holmes to develop his self locking fasteners concept by mating an asymmetrical female thread with a standard male thread. The resulting self locking threaded fasteners product was called Spiralock, and more than a decade of testing and development followed involving thousands of application trials to specify required sizes, dimensions, materials, and tolerances.

The company was renamed Spiralock Corporation as industries ranging from aerospace, truck and automotive to medical, agriculture and construction responded to the innovative self locking threaded fasteners ability to compensate for variations in manufacturing tolerance and process with its locking thread actually inside the joint. This eliminates the need for secondary thread locking devices or procedures, and can significantly reduce costly warranty claims and potential liability.

NASA was among the first to appreciate the advantages of the Spiralock thread, when designing the main engines of the Shuttle orbiter. Each of the three main engines develops 400,000 lb. of thrust and terrific vibration. But the Space Agency also wanted a 15-cycle reuse capability per fastener. Under its own test, NASA determined the fasteners in Spiralock-threaded holes did not back off or loosen when subjected to ten times shuttle-specified vibrations, and they stayed that way ten times longer than called for. NASA tests found the Spiralock-thread fasteners delivered 50 uses with no loss of clamping power. To this day, every shuttle engine carries no fewer than 757 Spiralock fasteners.

Caterpillar tested Spiralock self locking threaded fasteners for almost 18 months in the lab and almost two years in the field when seeking to improve its diesel engine applications in the 1980s. Caterpillar has used the Spiralock thread form ever since, as have many other diesel engine manufacturers including Volvo and Mack Trucks.

After lab testing the fasteners through billions of cycles of use, Biomet began using the Spiralock thread form for hip and knee orthopedic implants in the late 1980s. Depuy, GE Medical, and Theken Surgical are a few of the companies who have used the self locking fasteners for medical applications.

"As we celebrate our 80th year we've continually reinvented ourselves to help our partners compete in the marketplace, says Ed Palm, President and CEO of Spiralock Corporation. "As the demand for ever lighter, stronger, higher speed, vibration and temperature design continues, we look forward to helping our partners achieve their long-term cost and performance goals with our self locking threaded fasteners." Spiralock plans 80th anniversary festivities this fall.

For more info or detailed test data, including comparative graphic loading characteristics or photoelastic analysis/load vector comparison animation, visit Spiralock at www.spiralock.com; email slinfo@spiralock.com; call (800) 521-2688; fax (248) 543-1403; or write to Spiralock at Madison Tech Center, PO Box 71629, Madison Heights, MI 48071.

Spiralock Corporation
Kate Turowska
KTurowska@spiralock.com
Phone: (248) 543-7800
Fax: (248) 543-1403
http://www.spiralock.com