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Lock Washer Secures Safe Rendezvous to Space Station

April 1, 2013

On May 22, 2012, after eight years of preparation, Space Exploration Technologies (better known as SpaceX) launched the Dragon spacecraft atop a Falcon 9 rocket from Cape Canaveral Air Force Station in Florida. The spacecraft traveled more than 200 miles to reach its destination: the International Space Station (ISS).

With that launch, SpaceX made history. Dragon became the first commercial vehicle in history to successfully attach to the ISS—a feat previously achieved only by government-run space programs. These include NASA, the Russian Federal Space Agency, the Japan Aerospace Exploration Agency and the European Space Agency.

In August 2012, the Dragon was launched into orbit to complete its first commercial resupply services mission to the ISS for NASA. The primary payload did reach the ISS. However, a secondary payload did not reach its correct orbit.

On March 1, 2013, the Dragon was again launched into orbit. This time the spacecraft carried cargo for the ISS in its trunk, which is unpressurized and equipped with two solar arrays. The spacecraft rendezvoused with the ISS on March 3 and successfully berthed with the Harmony module.

During the extensive design and testing period, SpaceX spent a considerable amount of time making sure that bolts on the Dragon did not weaken under vibration and shock. Eventually, the manufacturer decided to use a lock washer and shim with each bolt to prevent loosening from static, dynamic and external-transverse loads.

SpaceX chose lock washers from Tiger-Tight Corp. The lock washers are coated with micro industrial diamonds embedded in an electro-less nickel matrix. During fastening, the diamonds penetrate and interlock with the bottom surface of the bolt head to create an extremely high retaining force.

The washers prevent self-loosening, additional settling and unintentional tightening. Equally beneficial, because the interaction is at the micro level, the washer surface is not damaged. This allows washers to be reused.

Made of carbon or stainless steel, the washers are available in 26 sizes, from M4 through M42.

Founded in 2002 by Elon Musk, SpaceX began design work on the Dragon spacecraft in 2004. The first Dragon spacecraft launched Dec. 8, 2010, and was successfully recovered following reentry to Earth’s atmosphere.

Besides designing, manufacturing and launching rockets and spacecraft, SpaceX has launched 40 commercial and government satellites into orbit. The company employs more than 1,800 people in California, Texas, Florida and Washington, DC.

For more information on lock washers, call 718-356-3376 or visit

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