Nickel-titanium shape memory alloys in practice

In this section you will be provided with the essential technical basics necessary for understanding NiTi-SMA in application.

First you will become acquainted with available semi-finished products and components which can be integrated into your products in order to integrate functions and generate new added value. You will learn what in general must be considered during design, for example with regard to actuation paths, actuation forces and operating cycles. For a better understanding this is explained in depth using an example. In addition, you will become acquainted with technical basics for integration/connection of SMA components and gain valuable insights into service life considerations. Would you like to find out more? Then simply download the complete course as a PDF HERE

Your first level of understanding will be obtained by reading our of thorough explanations. Later however, you will be able to merely refer to the condensed summary attached to the file. This is how you will deepen your understanding of SMA and develop new possibilities for yourself and for your products. This allows you to surprise your customers and positively inspire them. Because using SMA you can save them weight and costs, while making it possible to integrate functions. When considered in more detail, this alone results in further significant cost savings. With SMA you will not only increase your degree of innovation and profitability – you will also stay ahead of your market competitors.

Semi-finished products and components

The shape memory alloys (FGL) which are available to you at Ingpuls are based on the alloying elements Nickel (Ni) and titanium (Ti) (described as binary NiTi SMA). These can be obtained in various basic geometries (cylindrical, cubic, flat). Your semi-finished products are prepared individually for you via a suitable processing route, for example by forging, wire drawing or rolling, always accompanied by the associated heat treatments.

You may wish to refrain from further finishing semi-finished NiTi SMA products yourself since this implies a lot of effort or may not fit into your strategy. In this case, you can procure ready-to-use NiTi SMA components from us – as with the majority of our customers. After discussing an agreeing on your requirements we will take care of the rest: You can conveniently procure the finished component and install it into your products. We have a number of processing options available for this purpose. Depending on your preference, you can then receive your components already as fully-functional (usually heat-treated) or merely without a set functionality.

The SMA components which are available to you with Ingpuls and their respective advantages will be presented in more detail in the course (such as springs, wires, powder). For more details, please find these in our standard catalogue. If you have further going requests, we are able to take this into account; as even in case your need

exceed our previous competences we will find a solution for you. Because Ingpuls does not only act in a regional sphere but has an excellent global network in research, science and industry at its hands. And you can benefit from our steadily growing network of excellent partner companies.


Special components for actuator

Actuator components carry out positioning processes after installation or after assembly. For this purpose you frequently will be installing wires, springs or sheet metal elements which you can obtain from us in prepared form (e.g. pre-cycled and ready for assembly). The pre-cycling is typically used in order to compensate for

fatigue effects of the first cycles and thus ensures that from the first cycles on the operating points of your actuator system comply with narrow tolerance limits – see also section Quality Assurance (cyclic behaviour). More details on this can be found in the SMA course.

Condition of surfaces

The respective surfaces can also be produced specifically according to your specifications. Starting from a sometimes desirable oxidised surface (e.g. for better adhesion or insulation) you can avail of various levels of surface finishes, up to

electrolytically polished surfaces which are frequently required in medical technology.

Systems based on SMA

If you are looking for ready-to use systems based on NiTi-SMA, you can also ask for pre-assembled modules or entirely functional actuator system; if desired, you will also be able to obtain your electronic components for control (open loop) and regulation (closed loop). In this way, you can receive the functionality of a complete actuator

system and do not have to deal with technical, functional, design or alloying details. This saves you additional effort, as your actuator would then be ideally delivered – ready to plug & play.

Working principles specifically in actuators

Your SMA actuators usually operate by the principles of tension, compression, bending or torsion. Here, each case of your application requires various technical parameters, such as forces or actuation paths. In addition, often restrictions apply to your components relating to geometry or the environmental and use conditions. In case of actuators based on SMA, you can benefit not only from different activation principles but also from their combination and superposition. Intelligently combined, extremely complex systems with several motors, transmissions or brakes may be converged into a single system. This is the reason why many people often seem amazed how simple solutions based on SMA can be.

Together with you, we will first choose suitable semi-finished products and components or work out a suitable system together. Which component you use, depends entirely on the function you are looking for in your product. May you be looking for tensile actuators, compression actuators or rather torsional or bending actuators? You will find out in the SMA course which semi-finished product or which component you should ideally use in which case.

It is where the following applies: The basic principles of SMA components can be combined in various ways and thus generate additional advantages: Applied this way, SMA will assume exactly the function you want for your product.

Download your SMA course right now, to gain a better understanding of SMA and better perceive your potential applications.

Design of SMA

It is not to say that implementing the numerous advantages of SMA come at zero effort. In designing SMA, you unfortunately must take into account more parameters than you would probably be used to under normal circumstances. This already proves an exceptional obstacle for many customers. But no worries: When it comes to this point, we will be at your side to bridge the gap. You ought to consider some specific conditions of your application which we will support you to determine. Examples of these parameters are dependencies of your operating states, in particular load and temperature. Have you been thinking of a specific application? Then you can obtain our comprehensive requirements questionnaire. Due to the high complexity in the design of SMA, trying out things yourself will result in many open questions.

The design process with SMA requires a high degree of experience and know-how about handling SMA. Therefore, it has proven very helpful to inform us in detail already at an early stage about your project – this is precisely the situation for which we have developed our requirements questionnaire. It will help you to save costs and effort and at the same time is essential for us to be able to meet your expectations: Only this way can we ensure targeted development results which in turn achieves visible commitment within your development department. Side-by-side along with you, we will be able to develop innovative SMA solutions with a successful outcome.

Actuation paths and actuation forces of actuators

If you are looking at the application of SMA in actuators, primarily concerning, the forces and paths of actuation will be among your primary concerns. The actuation path is represented by the path which the actuating element of your actuator should travel in both directions. With SMA actuators, the actuation path (or actuator stroke) is achieved by heating. How this process works exactly and how you should choose the basic design parameters for the operating point of your actuator, you will be able to

find out in the SMA course. But no need to worry: Independently from the course, you will receive helpful support during the design phase as soon as you confront us with your request. This will help you achieving your desired result much faster than by trying out on your own. It will save you money and assure you results which you can show around much faster.

Switching times and response behaviour

You will also become familiar with characterizing switching times and more thoroughly understanding your actuator’s response behaviour. For this you will get to know the essential aspects relevant for the input and also discharge of the heat; not only regarding the influence of the alloy but also by the influence of additional boundary conditions. These include parameters such as the geometry of your actuator, the temperature gradient in the system, the electrical voltage or conditions of mechanical stress.

In the course, you will be able to follow the operation of an SMA actuator by means of a practical design example, making it possible to qualitatively understand its behaviour. And after having taken the course, you will understand why it says in this section Applications: In order to properly design your actuator, you should not only set the individual parameters correctly. You should also carefully coordinate their interaction with one another.

Service life of thermally activated and superelastic SMA

The service life of components of SMA depends on the load conditions that the component experiences. In other words the service life, as with all cyclically loaded metallic materials, is a function of the applied load(s).

Compared with conventional metal materials and equal strain provided, the structural service life of SMA is much higher. In any case, for NiTi SMA the functional fatigue is much more relevant than its structural counterpart. For more details on which exact factors are involved, please see the SMA course. Actuator systems are often geared at serving over a long timespan. The achievable cycle numbers for thermally activated SMA components (i.e. not superelastic components) vary strongly and highly depend on your requirements: Typical service life range from a few thousand to several hundred thousands of cycles. If it is necessary or desirable, you can also significantly exceed several million cycles.

Superelastic components in SMA achieve very long service lives when designed correctly in accordance to the applied loads. This is important since they deal with your loads differently than thermally activated SMA. Stents in medical technology, for example, must withstand 800 million cycles at constant temperature during the validation until they receive approval for use. After the SMA course you will be able to qualitatively estimate yourself what service life you can expect from your components: This is because you will be able to distinguish between application types, allowing you to use basic technical parameters for a first educated guess.

Joining technology for SMA

For the implementation of the connection and integration of components in SMA, a number of standard options are available to you: Here, particular mechanical and technical joining options are available to you. As a start, a small overview of the typical methods is included in the course.

What exactly you will learn in the applications section of the course:

You learn

  • which semi-finished products, components and surfaces are available
  • which components are used in actuator systems and why
  • which general factors should be considered with regard to actuation force and actuation paths (actuator stroke) with SMA already at the design stage
  • what the essential basics for service life considerations of SMA components are
  • which technical basics for the connection and integration of SMA components are available to you by standard

Recap on what you should have understood by now:

  • At Ingpuls, you can obtain the a highly diverse range of semi-finished products, components and actuator systems composed of NiTi SMA.
  • There is a difference between structural and functional fatigue.
  • The service life of your actuator can be designed and influenced by many parameters in order to suit your requirements. Besides the alloy, thermal and mechanical loading conditions are key.
  • The service life can be predicted very well by the design, its design is undertaken as to minimise cost.