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 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.

16:9

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

Messe K-Kunststoffmesse

kunststoffe-international.com

kunststoffe.de

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

Additive

Filamente für additive Verfahren

Andere Werkstoffe

Werkstoffe für additive Verfahren

3D Printing with Less Gloss

KLK OLEO offers plant-based PALMOWAX Ethylene Bis-Stearamide (EBS) as the green sustainable lubricant for plastic industries.

Thermoplastische Elastomere

Kunststoff-Aufbereitung

Verbundwerkstoffe / Werkstoffverbunde

Standardkunststoffe

Technische Kunststoffe

Blasformen

Extrudieren (KU)

Kunststoffverarbeitung

Compoundieren

Sustainable Lubricant for Plastic Industries

Much as when injection molding materials were being developed 30 years ago, the current trend in additive production is toward higher melting materials and materials with improved mechanical properties. The latter can be achieved, for example, by fiber embedding. In machine technology, the developments are increasingly aimed at adapting processing times, sensor systems, and quality monitoring to the demands of high-tech companies.  

Materials Manufacturers and Process Developers Face Growing Demands in 3D Printing  

Kohlenstofffasern / -matten

Rapid Prototyping

Rapid Tooling

Rapid Manufacturing

Selektives Laserschmelzen von Kunststoff, Metall, Keramik

Selektives Lasersintern von Kunststoff, Metall, Keramik

Spritzgießwerkzeuge

Pulver-Spritzgießen

Schleifen, Polieren

Additive Adolescence 

Arburg GmbH + Co. KG, Loßburg, Germany, is new on the market with its Freeformer 300-3X. The large machine will process three components using the Arburg Plastic Freeforming (APF) process, enabling the industrial additive manufacturing of complex functional parts in resilient hard/soft combinations with support structure as a world first. 

More Applications for Arburg Plastic Freeforming 

Resilient Functional Parts in Hard-Soft Combination 

Audi expects significant reduction in prototyping lead times for tail light covers by using a full color 3D printer. Compared to traditional methods, the turnaround times should be halved. The Stratasys J750 makes it possible to produce transparent, multi-colored parts meeting texture and color-matching requirements of Audis stringent design approval process . 

Audi Shortens Release Cycles with Full-Color Multi-Material 3D Printing 

Design in the Fast Lane 

As part of a collaborative initiative, the Brightlands Chemelot Campus focuses on the development and implementation of advanced additive manufacturing technologies. Three current biomedical projects illustrate the multiple possibilities for start-up companies in this market. 

Medical Device Developments at the Brightlands Chemelot Campus 

Polyamide

Breeding Ground for Additive Manufacturing 

Arburg Plastic Freeforming (APF) is based on qualified original materials in the form of plastic granulates as used in injection molding. Current researches illuminate influences on the resulting part quality of this additive process. Because the open system permits adaptation of the parameters, the mechanical and geometric properties of the parts can be optimized in a targeted manner. In this way, tensile strengths and part densities comparable to those of injection molded parts can be achieved. 

Arburg Plastic Freeforming: Current Investigations on Part Optimization 

Werkstoffprüfung, mechanisch

Droplets to the Beat of Milliseconds 

A new joint venture is getting a hybrid manufacturing cell ready for market. A screw-based plasticizing unit is mounted on a 6-axis robot. The novel processing approach facilitates additive manufacturing of structural parts from granular and fiber-reinforced standard compounds.   

High-Speed Additive Manufacturing of Fiber-Reinforced Structural Parts 

Compound

Flexible Fertigungssysteme

Layer-by-Layer from Granulate to Part 

ElogioAM B.V., a newly formed Joint Venture between Swedish Perstorp AB and Dutch 3D4Makers B.V, introduces new filament solutions. Facilan HT is specifically designed for 3D printing. It is a safe copolyester with high temperature resistance with heat deflection temperature of 89°C. Its high stiffness enables design optimization for faster rigid part print jobs. 

Joint Venture Introduces New Filament Solutions 

Durable Parts with Facilan HT 

Researchers at the Massachusetts Institute of Technology (MIT)  have shrunk 3D objects to nanoscale. The scientists' approach is based on a framework made of polyacrylate. It is a very absorbent material commonly found in diapers.   

System Produces 3-D Structures One Thousandth the Size of the Originals 

Technik Trend

Shrink Objects to the Nanoscale 

The combination of luminous fibers with plastics or fiber reinforced-plastics will open up a future-oriented field for functionalizing lightweight materials. Designers will appreciate being able to create previously unperformable filigree contour lines and uniform lighting effects on components. 

Accessing New Fields of Application by Integrating Optical Fibers 

Faserverarbeitung

Hybridtechnik

Pultrusion

Gewebe, technisch

Luminous Fibers as Design Elements  in Plastics Parts 

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.

issue 08/2022

issue 07/2022

issue 06/2022

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