Shape-changing structures (smart structures) are able to change their shape in response to external stimuli. The change of shape is self-induced and requires no artificial energy input. In view of the increasing demand for efficiency and resource conservation, shape-changing (smart) materials offer a sensible approach to integrating functionalities into a component without giving rise to additional energy and material costs. Even greater sustainability is achieved if the components are produced from bioplastics.

Prototype of a weather-sensitive smart facade system

Bioplastics for Shape-Changing Structures

Polylactid

Kunststoff Werkstoffe

Thermoplaste

Biokunststoffe

Additive Fertigung

Green Shape Changers

The K 2022 offered an immense range of innovations and application examples for – and with more – sustainable materials. Interestingly hereby was that bio-based versions were extremely popular.

Shoes made from waste gas: genetically modified bacteria produce ethanol from waste gas, which is then used to create plastic, e.g. for the Cloudprime shoes from On.

16:9

Thermoplastische Elastomere

Silikone

Messe K-Kunststoffmesse

kunststoffe-international.com

kunststoffe.de

Masterbatches

Additive

Polyethylen

Streifinger, Florian

Polyamide

Effektpigmente

Polypropylen

Faserverbundwerkstoffe

Andere Werkstoffe

Kunststoff-Rezyklat

Silikonkautschuk

Kautschuk / Elastomere

Is Bio the New Standard?

The production of particle foams with low densities and at the same time high molding quality is difficult, so the development of foamed polymer blends could simplify the entire processing.

Blend

Partikelschäumen

Kunststoffverarbeitung: Verfahren

Schäumen / Reaktive Verarbeitung

Study of expandable PLA particle foams – Influence of the blend system on processability and properties

The raw material used to produce Europlex Film LJ 21123/123 is derived from non-genetically modified sugarcane.

 Europlex Film LJ 21123/123 consists of a renewable raw material and can be shaped flexibly.

Röhm Is Developing Thermoformable PLA Films

Three solutions for increasing the productivity in the automotive, medical and packaging industries are presented by Tederic at K 2022 with the Neo injection molding machine series. T

The Neo·Ec combines electrical and hydraulic drives.

Spritzgießen

Mehrkomponenten-Spritzgießen

Spritzprägen

Spritzgießmaschinen

Kunststoffverarbeitung: Maschinen und Komponenten

Medizintechnik

Medizinprodukte

Applications in Three Key Sectors

Additive manufacturer Grafe has developed a new update for its matting agent in 3D printing.

Compared to its predecessor, the matting agent halves the gloss level once again. 

Farbstoffe und Pigmente

Filamente für additive Verfahren

Werkstoffe für additive Verfahren

3D Printing with Less Gloss

To an increasing extent, additive manufacturing is finding its way into series production. This was clearly shown at last year’s Formnext.

T-Crow night vision camera: except for the electronic components, the entire stand is produced additively. 

Polyetherketon

Verfahren für die additive Fertigung

Anlagen für die Additive Fertigung

3D-Druck-Anlage, pulverbettbasiert, Metall

Anlagen Additive Fertigung / 3D-Druck, Metall

Ehrhardt, Melanie

3D-Drucker (für FDM, FFF, etc.)

Hochleistungskunststoffe

Print-Ready for Series Production

The development of additive manufacturing processes, such as selective laser melting (SLM), has significantly extended the options for manufacturing extrusion heads. Extrusion head designs can now be realized with very slender geometries, which not only have integrated mixer functions, thereby improving the melt homogeneity, but can also be used to attach the mandrel to the head. This allows compact heads to be manufactured with a very high potential for saving operating costs. 

Improved Extrusion Head Designs thanks to Additive Manufacturing 

Extrusionswerkzeuge

Blasformwerkzeuge

Blasformen

3D-Printed Minimalists 

Evonik Resource Efficiency GmbH, Essen, Germany, has developed a polymer powder for applications in higher temperature range as part of its polyamide 6 series. 

Temperature-Resistant PA Powder for 3D Printing 

Selektives Lasersintern von Kunststoff, Metall, Keramik

Thermal Properties Modified 

Additive manufacturing processes provide a very high degree of design freedom and short development times. However, the nature of the process and the limited size of build chambers restrict the size of such components. Adhesive bonding enables additively manufactured components to be joined together to form large parts. 

Increase of the Adhesive Strength by Modification of the Surfaces 

Chemisches Fügeverfahren

Advancing into New Dimensions 

A gap exists between growth in equipment sales and numbers of manufactured parts. Most likely, a lot of experimentation is still going on. A symposium provided insights into projects, problems and prospects for additive manufacturing. 

Additive Manufacturing ¿ Between Growth Euphoria and a Sense of Reality 

Fluorkunststoffe

Putting 3D Printing to the Test 

The machine manufacturer Arburg has introduced an operating example of a digitalized AM-factory (additive manufacturing) at Hannover Messe 2019 (Hanover Fair). A turnkey system will functionalize vacuum grippers in six different versions "on demand" ¿ fully automated and 100 percent traceable. The new ATCM Scada-System simultaneously collects, visualizes, and transmits the relevant processing data. 

Fully Automated Traceable Additive Manufacturing of Small Batches and Single-Unit Parts 

Automatisierungstechnik

Industrie 4.0

Industrieroboter

Rückverfolgbarkeit, Traceability

Gripper Variants According to  Customer Requirements 

Injection is the process step in injection molding that is most quality critical. The injection speed profile and its reproducibility have a direct influence on the internal and external properties of a part. The adjustment of the injection step is therefore of particular importance. Engel injection-molding machines with electrical injection units now feature optimized setpoint computation of this profile, with clear visualization, which increases the process transparency and ease of operation. 

Improved Setpoint Calculation of the Injection Speed Profile 

Dynamic Injection ¿ Made Easy 

In order to qualify new materials for different 3D printing technologies, the company offers manufacturers of 3D printers and system providers an open materials platform. 

Henkel Wants to Qualify New Materials 

Open Materials Platform for 3D Printing 

Ford has selected desktop 3D printers to create various assembly tools, and can now produce jigs and fixtures, and even in highly complex designs, in-house at low cost. Ultimaker¿s open filament system enables the automaker to create parts with various filaments from a range of material manufacturers and meet specific material properties exactly. 

Ford Uses Additive Manufacturing with FDM Technology for Producing Assembly Tools in its Automotive Production 

Kunststoff-Halbzeuge

Printed Tools for High-Volume Production  

Into the Fourth Dimension  with 3D Printing

From Static to Adaptive Products with 4D Textiles

Textile structures can be equipped with shape-changing properties at all stages of their production. So-called 4D textiles are created.

Textile structures can be equipped with shape-changing properties at all stages of their production. So-called 4D textiles are created. They offer great advantages for medical technology and protective clothing. They can be manufactured by printing a pre-stressed textile using FDM printer.

The demands on products and components are constantly changing. This requires adaptable materials and structures. At the same time, resources should be saved and therefore less material used. Novel materials must be able to withstand these changes and the structures should be programmed to learn from the changes and react accordingly. Textile structures can be programmed at all stages of their production: functionality can be added at the level of fibers, yarns and fabrics and subsequently through additive manufacturing. In addition, there are textiles that change their form or function through an external stimulus. Such textiles are called 4D textiles (Box).

One research focus at the Institut für Textiltechnik (ITA) at RWTH Aachen University in recent years has been on multi-material structures consisting of textile membranes with polymer beam structures 3D-printed on top. The textile membrane can store mechanical energy. By releasing the stored energy, a two-dimensional structure becomes a three-dimensional structure with bistable behavior. The stable states are two different three-dimensional forms of the structure. The change between the stable states can be activated by external stimuli such as heat, electricity or moisture. This can lead to a change in function. It is now possible to program such structures. However, the accuracy still needs to be improved.

To produce the structures FDM 3D printers (Fused Deposition Modeling) are used (Fig. 1). Recent advances at ITA have been made with silicone 3D printing on pre-stressed textile (Fig. 2). Previous research at the ITA has already used various filaments such as polylactide (PLA), acrylonitrile butadiene styrene (ABS) and thermoplastic polyurethane (TPU) to produce 4D textiles.

The most used thermoplastic filament is PLA. The polymer, which is made up of lactic acid molecules, is characterized by its biocompatible and biodegradable properties. It is also easily recyclable due to its molecular structure. The decomposition of pure PLA, unlike many other polymers such as ABS, is not hazardous to health as no harmful vapors are produced. This is particularly important for the medical of great importance. Furthermore, printing with PLA on a textile substrate has been proven to have the highest adhesion. However, compared to other types of filament, PLA is brittle and can break easily when printed.

Thermoplastic elastomers (TPE) such as TPU are an alternative to thermoplastics. Compared to thermoplastics, they are much more flexible and durable. Since textiles are characterized by their flexible qualities, the use of TPE is interesting to produce 4D textiles. Due to the elasticity, the structure can better adapt to human movements, for example when used for orthoses. This increases the wearing comfort.

Hybrid material structures such as 4D textiles should find application wherever a change in the shape of the component or product is necessary. Due to their great adaptability, freedom of design and customizability they have a potential for applications. Possible areas of application include consumer goods, vehicle interiors and textile facades. Another focus of research at the ITA in recent years has been the use of 4D textiles in medicine especially for orthoses.

Due to the demographic change of the population, especially in the western industrial nations, the demand for orthoses is constantly increasing. In contrast to a prosthesis, an artificial limb, an orthosis is an aid in medicine. Like bandages, orthoses are used for illnesses and injuries of limbs or the trunk. Their functions range from stabilization and relief to correction and fixation. Compared to ready-made orthoses, which are mass-produced by machine, the production of individualized orthoses takes several weeks of manual labor. However, they also allow for a precisely fitting wearing period of several months.

During research at ITA, the production of a ready-made and individualized orthosis was developed using 3D scanning and 3D-printed 4D structure (Fig. 3). The limbs are scanned in a few seconds to generate a CAD model for an individual orthosis. The structure is then produced using the FDM process. The special feature here is the printing on a circular knitted fabric. The printer has a circular shaft instead of a printing bed (Fig. 4).

Up to now, the developed process can only be produced on a small scale. The aim is therefore to scale up both the production and the scale both the production and the effects. This would make it possible to move beyond the prototype phase and develop industrial applications. But challenges still need to be overcome for this to happen. These include, among other things, the print bed size, the feeding of the textile in processes and dimensions typical for the process, the realization of the pretension over a large area and the use of diverse materials in 3D printing. In addition, sustainability aspects are also to be considered. However, the results so far already show that there are many technical innovation possibilities for 4D textiles.

RWTH-Aachen Inst. f. Textiltechnik (ITA) 

https://www.ita.rwth-aachen.de

Ausgabenartikel

4D materials are ideal for personalized medical technology such as orthoses.

Fig. 1. 4D textiles can be produced by means of using an FDM printer.

Fig. 2. In the production of 4D textiles at ITA, a structure is printed onto a pre-stretched textile. The shape of the piece is then created by relieving the prestress on the textile.

Fig. 3. Prototype of a 4D textile orthosis for the elbow produced at the ITA: it can be individually tailored to patients and is very comfortable to wear due to the use of textiles.

Fig. 4. A 3D printer with a cylindrical print bed is used to produce 4D textiles.

KUint8-22_ITA_Kelbel - Hauptartikel

Formverändernde Textilien, sogenannte 4D-Textilien, bieten beispielsweise für die Medizintechnik große Vorteile. Herstellen lassen sie sich mittels FDM-Druck.

Mit 3D-Druck zu 4D-Textilien

4D textiles are textiles or textile products that can change their function or shape over time. This change is stimulated by an external stimulus. They can be used, for example, in rehabilitation medicine. Support structures that are worn close to the body and react adaptively to changing requirements can be individually adapted to the wearer by means of 3D printing. Textiles additionally increase the wearing comfort. 4D textiles are manufactured on the surface by printing a pre-tensioned textile using FDM printing. By relieving the tension on the textile after production, a three-dimensional form with bistability is created from a two-dimensional one.

Hannah Carlotta Kelbel, M. Sc., researches on the development of 4D textiles since 2018. Since 2020, she has been a research associate at the Institut für Textiltechnik (ITA); <a href="mailto:hannah.kelbel@ita.rwth-aachen.de">hannah.kelbel@ita.rwth-aachen.de</a>

Dipl.-Des. Helga Ahrens-Wels has been working as a research associate at ITA in the Additive and Joining Technologies department since 2019; <a href="mailto:helga.ahrens-wels@ita.rwth-aachen.de">helga.ahrens-wels@ita.rwth-aachen.de</a>

Katarina Winands, M. Sc., has been working as a research associate at ITA in the Additive and Joining Technologies department since 2021; <a href="mailto:katarina.winands@ita.rwth-aachen.de">katarina.winands@ita.rwth-aachen.de</a>

The authors would like to thank Schneider Technologies for the excellent cooperation.