I n t r i n s i c  D e v i c e s  I n c o r p o r a t e d

Use of Shape Memory Alloys in
High Reliability Fastening Applications

In 1962 the shape memory effect is discovered in NiTi alloys by the U.S. Naval Ordnance Lab. The nominally equiatomic NiTi alloy was dubbed "Nitinol" for Nickel Titanium Naval Ordnance Laboratory.

The first major application for the technology is launched in 1971 by Raychem Corporation of Menlo Park, CA. The product is a line of 3000 psi hydraulic couplings used to join titanium tubing on the U.S. Navy / Grumman F-14A. Over 300,000 couplings are put into service in this demanding application. Raychem sells the couplings under the name Cryofit®.

The British Royal Navy specifies 6000 psi Cryofit couplings for it's Trafalgar Class nuclear submarines in 1975. The U.S. Navy begins using Cryofit on its surface ships in 1977. All of these couplings utilize a cryogenic nickel-titanium-iron, NiTiFe, alloy similar to Intrinsic's Alloy C. Raychem trademarks the name Tinel® for its family of nickel titanium alloys.

In 1974 Raychem begins production of Cryocon® electrical connectors for use in the navigation system of the Trident missile. These connectors utilize shape memory rings to compress split cylindrical contacts onto mating pins. The Trident connector has 16 contacts ganged together in a plastic housing. See UniLok Application Examples for addition description. Cryocon connectors are unique in offering signal and mechanical integrity in this high shock and vibration environment. Cryocon connectors are later used on missile, munitions and naval bulkhead feedthrough applications, primarily in Europe.

In 1983 NiTiFe rings enter production for sealing metal caps to plastic headers in the assembly of detonators for the UK AWRE/ROF.

In the early 1980's Raychem develops a new nickel-titanium-niobium, NiTiNb, alloy that offers similar performance to the cryogenic alloy, but without the need to hold parts at cryogenic temperature prior to installation. Intrinsic's Alloy H is similar to this Raychem alloy. In 1985 Raychem launches its first major product using the new alloy, Tinel-Lock®. This is a family of NiTiNb rings used to terminate cable EMI/EMP shielding braids. One of the first large programs to use Tinel-Lock is the FMC Bradley Fighting Vehicle. Since that time, Tinel-Lock has seen extensive usage in military and aerospace applications including various satellite programs.

In 1988 NiTiNb rings enter production for the assembly of piezoelectric accelerometers and in 1989 as drivers for 1/4 inch tube fittings used on naval gage lines.

Beginning in 1989, NiTiFe rings are used in sonar towed arrays to clamp polyurethane hose to fittings. Rings up to 5 inch diameter are produced.

Beginning in 1990, NiTiNb rings are used to terminate metal wiring conduit on civilian aircraft.

Raychem launches a standardized line of shape memory alloy fastener rings in 1992 under the name UniLok®. By 1993 the rings find uses in a broad range of new applications including clamping a bundle of optical components in a particle counter, sealing a cover to a pressure sensor, joining aerospace valve components, retaining a 10 inch diameter nuclear seal and providing a stop on a rocket motor shuttle valve.

After pioneering the commercialization of NiTi shape memory alloys for more than 20 years, in the early 1990's Raychem decides to divest its shape memory metals division. Intrinsic Devices purchases Raychem's shape memory fastener business, including the UniLok product line, in 1994.

In the 30 years since their commercial introduction, shape memory alloy fasteners have proven their reliability in a range of demanding applications. Service lifetimes in excess of 30 years have been demonstrated. Their consistent response to static loading, fatigue, high temperature exposure, thermal cycling and general corrosion allow these fasteners to be confidently engineered for new applications. Given continuing strides in alloy production, metallurgy and manufacturing processes, use of this technology is now spreading far beyond its military/aerospace roots.

  cryofit nitife coupling for titanium aircraft  tubing
Cryofit® couplings
  cryocon electrical connector with NiTiCu rings
Cryocon® connector
  tinel-lock sma braid termination rings
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Copyright 2003 Intrinsic Devices, Inc. All rights reserved.
UniLok® is a registered trademark of Intrinsic Devices, Inc.
Cryocon®, Cryofit®, Tinel® and Tinel-Lock® are registered trademarks of
Tyco Electronics