Nitinol Spring，（NITI Spring）Shape Memory Alloy（SMA） Spring

Product Information 

Nitinol spring is a type of shape memory spring. Nitinol is a nickel-titanium alloy with the typical ratio 40-50% nickel, 50-60% titanium known as a shape memory alloy (SMA), a metal alloy that demonstrates pseudo-elasticity and the shape memory effect. The shape memory effect is when a material returns to its pre-deformed shape by heating. Shape Memory Alloys (SMA) are one of the most promising smart materials available today, and they can provide novel solutions in several fields and for various applications (e.g. actuator, biomedical application, clamping systems, etc.). Shape memory nitinol demonstrates a unique ability to recover its initial shape after deformation through a reversible thermo-elastic phase transformation. This ability allows shape memory nitinol to recover from large strains, either spontaneously (pseudoelasticity) or through an increase in temperature (Shape Memory Effect). Among the commercially available Shape Memory Alloys, nickel-titanium (Ni-Ti and Ni–Ti-based) alloys are outstanding due to their excellent performance, reliability, and strain recovery properties. Ni-Ti alloy is attractive for various medical applications due to its biocompatibility, corrosion resistance, and fatigue behavior.  Nitinol is well known for its thermo-mechanical properties of superelasticity and shape memory effect. Shape memory refers to the ability of Nitinol to undergo deformation at one temperature and then recover its original, under formed shape upon heating above its transformation temperature. Super elasticity occurs at a narrow temperature range just above its transformation temperature; in this case, no heating is necessary to cause the under formed shape to recover, and the material exhibits enormous elasticity, some 10-30 times that of ordinary metal. These unusual properties are being applied to a wide assortment of applications in a number of different fields including the medical device and aerospace industries.

Nitinol Synonyms

Nickel Titanium, shape memory Nitinol, Muscle Wire, Tinel, NiTi, Ni-Ti, nickel-titanium shape-memory alloy (SMA), Alloy N, Alloy M

Nitinol Spring Specification

Dimensions

Size： customized

Standard：ASTM F2063

AF:-10 ºC(Superelastic)-100 ºC, customized

NiTi

Per your request or drawing

We can customized as required

Nitinol pre-trained 1-way memory helical/coil spring contracts and exerts force when heated to 45C. Once cooled to room temperature, the spring requires almost no resistance to collapse it. Recommended maximum expansion when cold: 50mm (without hooks). This spring pulls with a force of up to 400 grams, but in order to prevent damage to the spring's structure, the recommended maximum load should not exceed 230 grams.

Nitinol Products

Other: Spherical Nitinol Powder, Nitinol crucibles, Nitinol nuts, Nitinol bolts, Nitinol heating elements, and Nitinol shielding screens.

Properties（Theoretical）

A shape memory alloy undergoes a phase transition changing from one crystal structure to another at a specific temperature, with substantial forces in theprocess. The most common shape memory alloy is Nitinol (Nickel Titanium Naval Ordinance Lab). Variations in the ratio of nickel to titanium and variations in processing create different nitinol characteristics. Nitinol can exhibit a shape memory effect, where it transitions from one crystalline structure to another, and moves with substantial force in the process, upon the application of heat at a temperature specific to the alloy. Super-elastic nitinol, shares the ability of the alloy to stretch up to 30% of its length without permanent deformation, a highly unusual characteristic for a metal. ATT COMPANY both superelastic and shape memory nitinol in wire, sheet, and tube form. For most projects, we recommend wire as it is the least expensive and most versatile form. In comparison, sheet allows you to create 3-dimensional forms that move, and tube allows you to pump heated/cooled fluid directly through the tube for mess-free, highest efficiency activation. Nitinol can be welded in an oxygen-free environment (use shielding gas).

1. Values listed are for full martensite to austenite transition.

2. Similar to 300 series stainless steel or titanium

3. Highly nonlinear with temperature

4. Hysteresis can be significantly reduced by partial transformation or ternary alloys.

Advantages OF Nitinol Spring

1.    Superior reliability.

2.    2-3x higher heat sensitivity compared to waxy components.

3.    No gas or liquid leaks.

4.    Shorter response time to temperature changes.

5.    Our Nitinol can be used in standard compression, extension, or torsion springs.

6.    Lowered the total cost of modern SMA springs.

TRANSITION TEMPERATURES

Nitinol changes its crystalization pattern at more than 1 temperature point. The stoichiometric ratio of Ni to Ti, impurities, and post-processing determine the mechanical characteristics of your nitinol.

All transition temperatures are specified in Celsius ºC. The temp indicated is an approximation of where the alloy begins to undergo the crystalline transformation. It occurs over a fairly wide temperature range. So, a 40C rated wire will perform faster and stronger at 80C.

At room temperature, an 80C wire will be substantially more malleable and soft to your fingers, the 40C will be more difficult to bend, and the 15C will feel like spring steel. The 15C will react to a heat source up to 80C, while 80C NiTi is more suitable for exposure up to 150C. The 15C will be malleable at and below freezing temperatures.

RETURN TRANSITION PHASE

A common question concerns the ability of the alloy to transition back to its cold shape upon cooling (double dipping). This alloy will exhibit a slight mechanical effect upon cooling, however it does not exhibit nearly the same level of energy as upon heating. The effect is most noticeable in the 15C wire and NiTiCu, however it is mildly present in all of these alloys, and can be emphasized with proper training.

Applications of Nitinol Spring

Nitinol Wire is used for many different medical and industrial applications. The table below gives some typical engineering applications for each of our standard Nitinol medical grades:

Nitinol springs have the following uses:

- Nitinol is used to produce bend-resilient glasses frames.
- Nitinol springs are also used as mechanical watch springs.
- Nitinol can be used as a temperature control system; as it changes spring shape, it can activate a switch or a variable resistor to control the temperature.
- Nitinol is used in cell-phone technology as a retractable antenna, or a microphone boom, due to its highly flexible nature and mechanical memory properties.
- Nickel-titanium alloys are used to make the underwires for underwire bras.

Packing of Nitinol Spring

Standard Packing:

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 440 gallon liquid totes Special package is available on request.

ATTs’ Nitinol Spring is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition.

Chemical Identifiers