Over the years, there has been considerable growth in the adoption of nitinol – especially in the product development and manufacturing spaces. Thanks to its unique ability to conform to any shape and return to its original form if necessary, many manufacturers have found different uses for it.
This article will look into the intricate details of this transformative material, as well as how to get your hands on some of it for your manufacturing project.
What Is The Nitinol Wire?
Nitinol is one of the most interesting metal alloys on the market today. Known for its ability to adapt its physical shape based on the requirements, the alloy – which is actually pronounced as “night in all” – has become one of the most popular on the planet.
In most cases, nitinol is applied in the medical field. But, that doesn’t mean it can’t be used for other things. In fact, as time goes on, more functionalities of the wire have been found, with more people asking “What is Nitinol wire and how can I get some of that?”
How Was Nitinol Created?
Nitinol is a simple alloy that is made from a combination of nickel and titanium. The ratio of both materials is usually equal, although adjustments can always be made to this combination. So, when constituent materials are adjusted, there is a significant chance that you see changes in the property’s features as well – from its physical appearance to its temperature of transformation.
Nitinol’s creation was actually a happy accident. While scientists had been working on shape memory alloys for a long time, they hadn’t necessarily made any progress.
In 1959, however, William Buehler – a metallurgist at the Naval Ordinance Labs – came upon an accidental breakthrough. While working on a new missile cone nose, Buehler was working on different metal alloy options. He eventually found nitinol as part of one of his many experiments.
When he discovered that this new material could deliver the shape memory effect, Buehler decided to name it after its composite materials – Nickel (Ni) and Titanium (Ti), as well as the name of his workplace (the Naval Ordinance Labs). This combo eventually formed NITINOL.
Most nitinol ingots are processed via melting- whether it is vacuum induction melting or vacuum arc melting. Following the manufacturing, a nitinol wire experiment can also be made to ascertain its efficiency and properties.
The Shape Memory Effect
In metallurgy, a shape memory alloy (SMA) is a type of metal alloy that can lose its form and return to its original form based on what you want. Most SMAs get deformed when in their cold state or room temperature, then get confirmed to their original state when you apply some heat to them. This capability is what metallurgists call the shape memory effect.
So, how does Nitinol wire work with this physical adaptability?
We’ve already cleared the composition part of nitinol – the material usually contains mostly nickel and titanium.
When stored at room temperature, the material easily loses its form and can be twisted into just about any shape you need. Once you apply heat to it, nitinol will return to its original form, essentially “remembering” its initial shape. The material’s adaptability and flexibility make it especially perfect for a range of applications.
For many people wondering how to use nitinol wire, it is important to note that the transition temperature of nitinol – essentially, the temperature and physical condition needed for nitinol to change its shape – can be repeated. This means that the shape memory nitinol wire can be used over multiple cycles without stress.
Many nitinol wire manufacturers tout the wire’s ability to withstand different deformation and realignment cycles as a huge benefit. It essentially means that the material is a great choice for making products that need to be used in the long term.
Usually, the nitinol material transforms when it is put under temperatures of about 180°F. However, you should note that these values can vary based on a number of factors – including and especially the combination of materials and the hat treatment method used in manufacturing it.
Nitinol: Physical Properties
As you would expect, Nitinol’s most touted properties are its impressive elasticity and ability to adapt to different shapes. It is flexible enough to be transformed and then revert to its original state, but it can also be stretched significantly – leaps and bounds more than the average metal.
Besides these, however, nitinol has several other physical properties. Some of those include:
- Appearance: In its most undiluted state, nitinol comes with a bright silver look. The appearance is the same as any other metal, so the material isn’t necessarily unique. Of course, this is what you’d expect since the nitinol wire composition is primarily nickel and titanium.
- Melting point: Nitinol’s melting point is important because it plays a role in signifying the point at which the material starts to transform. In most cases, nitinol would need to be subjected to about 1310 °C for it to melt. You should note, however, that this isn’t necessarily accurate. The nitinol wire composition affects its melting point, and that number could also change based on the wire’s manufacturing process.
- Resistivity: Thermal resistivity for nitinol stands at 82 ohm-cm in higher temperature. When temperatures drop lower, the thermal resistivity of the material also goes low – to about 76 ohm-cm.
- Conductivity: As for thermal conductivity, nitinol holds a rating of 0.1 W/ cm-°C.
- Heating Details: Nitinol withstands up to 0.077 cal/ gm-°C in heat capacity, while its latent heat stands at 5.78 cal/ gm.
Mechanical Properties Of Nitinol
With an ultimate tensile strength that ranges between 103 and 1,100 MPa, it’s safe to say that nitinol isn’t necessarily the strongest material on Earth. Still, it definitely does its best. Of course, you should note that the content of titanium in nitinol is one of the biggest determinants of this.
To get a proper picture of how strong nitinol is, consider the fact that stainless steel has a tensile strength rating between 300 MPa and 2,400 MPa. While this number can vary based on the material composition of the steel as well, the fact that nitinol has a comparable rating shows that it can provide considerable durability.
Once nitinol is taken above its transformation temperature, it adds density and strength. Still, its formability is what makes nitinol so useful – especially for medical applications.
Nitinol also has impressive corrosion resistance – even more than stainless steel – and, it is biocompatible; meaning that you can put it in a human’s body without posing a threat to them.
Besides those, the material also has the following mechanical properties:
- Elongation To Fracture: With a 15.5% elongation-to-fracture ratio, Nitinol has an impressive ability to withstand change without cracking its formation or shape.
- Yield Strength: Typically, nitinol comes with a yield strength of 560 MPa in high temperatures. The number reduces drastically to 100 MPa in low temperatures.
- Elastic Modulus: In high temperatures, nitinol has an approximate elastic modulus of 75 GPa – a number which reduces to just 28 in low temperatures.
The Nitinol Cable Construction Process
How To Shape Nitinol Wires
In the next module, we’ll look into how to shape the nitinol wire perfectly.
As explained earlier, the features that most people look into when working with nitinol wires are the shape memory effect and the pseudo-elasticity.
In high temperatures, nitinol becomes incredibly stiff. However, when it is cooled, the alloy takes on a flexible and rubbery shape that allows it to easily be deformed. This is the point where you form it into your desired shape. When nitinol is heated to the transformation temperature, the metal easily goes back to its initial shape.
Remember that you can always make adjustments to the temperature where nitinol’s shape memory kicks in. However, for these adjustments to be made, you also need to change the alloy’s chemical composition and switch the hat treatment method.
All in all, keep in mind that the transformation effect in nitinol is reversible – and that this transformation happens instantly, regardless of the direction.
You should also note that nitinol itself isn’t usually the only thing that’s in the wire. Due to its propensity for deformation, wire manufacturers tend to add other materials to a nitinol strand – stainless steel being one of the most popular.
This addition provides more strength to the cable, while also improving its longevity.
When using nitinol wire, you’d need to start by defining the shape you want it to be in and setting the wire. The process that is employed is primarily through heating, where you constrain the nitinol element on a fixture of the desired shape and apply the right heat treatment.
As you consider how to make a nitinol wire, you should know that the heat treatment method you use in setting shapes for it are similar, whether the nitinol is in its superelastic or shape memory form.
Finally, you also want to pay special attention to the treatment parameters you choose when setting the shape – as well as the physical properties of the nitinol wire you have. In general, you can set shapes with temperatures as low as 400°C. But, based on the wire’s composition and properties, that temperature could easily change.
When the time comes to cool the wire, this can usually be done through a simple water quench or a quick air cooling sequence.
How Nitinol Wires Can Be Cut
When a nitinol wire is being cut, you need to ensure that you have the right wire cutters. Whether it’s an automatic nitinol wire cutter or a manual one, ensure that the cutter’s blades are strong enough and more robust than the wire itself.
Most nitinol wire cutters are made of carbon steel with tungsten carbide layering. You can find them in different shapes including:
- Round-head wire cutters
- Oval head wire cutters
- Taper head wire cutters
Get the right option, and you’ll find that crimping a nitinol wire will be as easy as possible.
Nitinol Industrial Applications
So, you might be thinking – why should I buy a nitinol wire? Well, nitinol is one of the most versatile materials available right now, with functionalities that vary significantly. Some of them include:
Medical Industry Applications
Amongst its many applications, nitinol has gained the most prominence from its use in the medical field. Thanks to the material’s biocompatibility, shape memory, and elasticity, the material helps in the manufacturing of multiple devices and medical components. Some of these include:
- Orthodontic Archwires: In the field of orthodontics, nitinol is used in manufacturing archwires. A nitinol orthodontic wire is applied in the orthodontics field to apply extensive forces to help move and align teeth in the desired position.
- Developing Stents: Nitinol is used in building surgical stents that are broadly used in conducting minimally invasive surgical procedures. These surgical procedures primarily look to treat narrowed or blocked blood vessels. These nitinol stents can easily be pressed into small diameters for delivery, then they can be expanded back into their original shape when they are deployed. With their flexibility, nitinol stents help to improve the overall efficiency and delivery of surgical procedures.
- Surgical Tools: Thanks to its superelasticity, nitinol is also applied in the production and use of surgical equipment across the board. From stone retrieval baskets to retrievable filters and biopsy forceps, nitinol wire uses are incredibly extensive.
- Dental Instruments: Like the general medical field, nitinol wire applications also extend to the dental space. The material is used in different applications, from endodontics (shaping and treating root canals during procedures) to creatine endodontic files and other dental implants. Dentists and manufacturers rely on its flexibility a great deal, and they use the material for a myriad of applications.
Aerospace and Automotive Manufacturing
Away from the medical space, nitinol wires have also found significant use in the aerospace and automotive sectors. Some of its most significant uses include:
- Developing Motors & Actuators: In general electrical engineering, it is almost impossible to overstate the use of actuators and sensors. Nitinol actuators can help to convert thermal energy into mechanical work, allowing them to be used in applications such as flap and valve control – as well as manufacturing engine components for different aerospace and automotive systems.
- Building Vibration Dampers: Nitinol strips and wires can also be integrated into structures that help them to provide optimal vibration dampening and noise reduction. This provides a base for aerospace and automotive components to work better and more seamlessly across the board.
Consumer Goods Production
Nitinol is also applied in developing different new-age consumer products, thanks again to its unique qualities. Some examples of products that the material has been used to make include:
- Smart Materials: Nitinol is applied in developing smart products and electronics, with applications such as smart textiles, foldable displays, self-repairing phone cases, and much more.
- Eyeglasses: Nitinol frames are renowned for their flexibility and ability to withstand squeezing or deformation. They are also durable and resilient, meaning that they don’t break easily and can hold in a lot of contact.
- Electronics: Mobile phones require components such as cameras, optical image stabilizers, antennas, and microphones. All of these can be made using nitinol.
You should note that these are just some of the many applications of nitinol. With its unique properties, the material is incredibly versatile and able to handle different forms of applications. And, as time goes on, there is no doubt that more manufacturers will be looking to buy nitinol wire for its different uses.
Why Are Nitinol Wires So Advantageous?
The benefit of nitinol comes from its elasticity and shape-changing ability. This allows it to be very flexible – a property that materials such as stainless steel just don’t have.
The nitinol wire composition remains a major factor for you to consider when using it, but all in all, it is a good option for different functionalities.
Another benefit of nitinol wire medical functionalities is the material’s strength. Consider in the dentistry profession, for instance – nitinol is used to make braces, and thanks to its shape adjustment, it holds on to its tension over time. Materials like stainless steel that lose tension won’t be able to last, and patients would need to get new braces every now and then. With nitinol, you never have to worry about this. Fewer trips to the dentist mean you get to save money and energy in the long run.
Possible Cons Of Nitinol Wires
If you’re a manufacturer or a user, attachment will most likely be the biggest issue you face with nitinol wires. Depending on their current phase, nitinol wires can be stiff or flexible. So, welding or bonding them can be a bit of a challenge.
You could try crimping a nitinol wire mechanically to the other, with materials like stainless steel helping to ease the attachment. The next step will be simple welding, which would aid in creating the final product.
To do this, however, it is important that you work with a skilled and experienced wire manufacturer. This is why we recommend giving us a call at Tuolian Metal. We can develop the right techniques for using nitinol wires, thus helping your project. If you need further advice, feel free to reach out to us as well.
Nitinol is one of the most fascinating materials out there. With its pseudoelasticity and shape memory effect, the material is flexible enough to serve different purposes.
Looking for where to buy the nitinol wire? Give us a call at Tuolian Metal. We are the best nitinol wire suppliers in the market, and we’ll be able to get you what you need.
Frequently Asked Questions
How much is nitinol wire?
Generally, you should be able to get nitinol wire for about $427 per kilogram. However, note that the price you pay will also vary based on the manufacturer and supplier.
The nitinol wire price is one of the most significant factors to be considered when making a purchase. However, you should also remember that a cheaper wire doesn’t necessarily mean it’s the best for you. We recommend getting in touch with us at Tuolian Metal to discuss the best nitinol wire option for you while considering all factors.
Is nitinol wire used in surgery?
Among the many uses of nitinol wire in the medical field, the material can also be used for surgery. It works for vascular surgeries, as well as in manufacturing medical prostheses and other tools.