Sustainability: why it’s all everyone is talking about

Industrial 3D printing – more commonly known as additive or generative manufacturing – is growing in importance at a huge pace. New areas of application are taking shape and advances are constantly being made in material development and process optimisation.

Many of the materials used come in powdered form and require the expertise of powder specialists in their manufacture, quality assurance, processing and logistics. Additive manufacturing had its origins in rapid prototyping. The crucial advantages of reducing cycle times from product development to manufacturing to market launch, have all opened the way for this emerging technology to be used extensively in mass production.

It is now possible to customise products and incorporate additional functions without difficulty in much shorter timeframes and at lower costs. Additive manufacturing may therefore give companies an excellent opportunity to differentiate themselves from the competition, act more swiftly, and use fewer resources throughout their entire manufacturing process chains. This method of manufacture has now found its way into many industries. It offers new opportunities both for sophisticated fields such as Healthcare, Automotive and Mobility and Aerospace, as well as mass markets such as Lifestyle and Consumer Goods or Production and Industry.

The focus is always on establishing points of differentiation and remaining viable for the long-term using industrial 3D printing. Finding the best way to integrate the complex variety represented by this future-oriented manufacturing technology has become the responsibility of the Fraunhofer “Generative Manufacturing” alliance which was created for the purpose. The alliance brings together 20 Fraunhofer Institutes throughout Germany that deal with additive manufacturing with a focus on research into materials, technology, engineering, quality, and software and simulation – in other words, the entire process chain.

The importance of the alliance

Materials research provides answers to current questions in the areas of energy, healthcare, mobility, IT, construction and living. The latest lightweight materials save costs and energy, ceramic micro fuel cells supply power to electronic devices, and new materials based on sustainable resources ease the burden on the environment.

As far as additive manufacturing is concerned, all the institutes in the alliance focus on:

  • Metals – steels, titanium and aluminium
  • Ceramics – oxides, carbides, silicate and bioactive ceramics
  • Plastics – polymers/thermoplastic materials.

Metallic, ceramic as well as polymer-based powders serve directly, or are incorporated into filaments to serve as raw materials for the most additive manufacturing methods. Their morphology and material composition influence not only how they can be worked during the manufacturing process, but also – and critically – the component properties that can be achieved.

As the basis for many innovative products and to optimise additive manufacturing processes, the Fraunhofer Institute applies technologies to adapt the powdered materials to suit the manufacturing processes and product properties. To achieve this, the powdered materials are coated with a thin layer using physical vapour deposition (PVD) or atomic layer deposition (ALD). These can address a range of functions, depending on the coating material used. For example, the coating material can be used to micro-alloy metal powders to optimise specific critical material properties, such as crack-sensitivity or ductility.

Flow properties can be significantly improved as well, enabling even the highest agglomerating powders to be processed. This makes it possible to adjust the electrical conductivity of the powder – and thus of the end product – and improve its corrosion resistance.

Future developments will focus on the deposition of thin, hard material layers, for example, which will open up new opportunities for material development. There is also an interest in scaling to larger production volumes to make industrial implementation possible. The Fraunhofer Generative Manufacturing alliance also offers individually adapted materials for any special applications, individual processes and entire process chains, which can also take conventional technologies into account.

Simulation is now considered a standard tool in product development and optimisation in many industry sectors. The finite element method (FEM) is routinely used to test the structural mechanics of components.

Simulation provides very important insights into the development process, and in many cases, it substantially reduces the development time for new products.

The situation with process engineering is quite different. The only routine solution has, until now, been to optimise turbomachinery using computational flow dynamics (CFD).

Now, the Discrete Element Method (DEM) can offer suitable state-of-the-art tools to simulate particle flows and mechanical process workflows. Dr Jorge Carregal Ferreira, head of the Rocky DEM unit at the Grafing office of CADFEM GmbH, explained: “Physical simulation has previously been used only to a limited degree, if at all, in mechanical process engineering to date.

“Reliance is generally placed on experience or on lab tests. But the limit is regularly reached when scaling-up from test benches in the lab to large-scale plant intended for manufacturing, or when transferring from a familiar production plant to a new facility.

“In these areas, simulation lets us understand the key influences and make the right decisions regarding process parameters. The result is significant cost savings, since the risk of having to readjust the production plant is reduced. It is also possible to perform parameter studies, sensitivity analyses and optimisation processes to establish the right process parameters.”

The stimulus of simulation

Sustainable manufacturing therefore demands a sound understanding of all the physical effects of the individual processes, or what are known as “unit operations”, which combine to form the overall process. Here, too, physical simulation can provide important insights and improve the overall manufacturing process efficiency. Mechanical process engineering is very strongly characterised by particle and material flows. Materials and bulk solids are crushed, transported, classified, mixed, separated and treated. Entire components are transported, sorted, treated and further processed.

“Using the DEM, we can simulate these processes, understand and optimise them,” said Dr Ferreira. “This
takes account of the movements and contacts between
the particles. With a very large number of particles, often more than a million, this calls for suitably powerful hardware. With GPU (graphics processing unit) technology, the DEM now lets us simulate a much larger number of particles and the actual particle shape.”

Quality control in mixing processes is based on quality of the mixture and throughput performance. In practice, measuring mixture quality is very difficult, since the plant must be stopped, and access allows for only a limited test sample. “This is where the DEM simulation helps to make
the process transparent, since we can determine the quantitative mix quality at any time and at any location using the right statistical analysis,” he added.

“We can then determine the impact of the influencing parameters and input values, which will enable us to recommend the ideal operating parameters.”

In the pharmaceutical industry, tablet coating remains an important element in the tablet production process. Although the tablet itself contains the expensive active ingredient, for reasons concerning customer acceptance the coloured surfaces must be produced with a high level of accuracy and no trace of damage.

These coating processes are therefore crucial, since even a small number of tablets with damaged edges must be disposed of as waste, which incurs high costs. With DEM simulation it is possible to arrange the upscaling and process parameters to keep waste to a minimum.

Ferreira went on to conclude: “We assume that DEM simulation will become a standard tool in mechanical process engineering in the next three to five years. That is comparable to the situation in mechanical engineering, in which the finite element method has grown to become a standard tool in the past 15 years and is now used on a routine basis. And just like the situation with mechanical engineering, simulation will result in significant changes in future process engineering.”

All issues relating to this are discussed at POWTECH events, making them an ideal forum for specialists in the process industries and engineers relying on the future technology of additive or generative manufacturing.

POWTECH events also include solutions for de-dusting metal powders, and provide the latest developments for processes, such as size reduction, agglomerating, separating, screening, mixing, storage and conveying.