Sirmax accelerates his production of its self-extinguishing (flame retardant) compound a fully dedicated line in the USA.

Extremely high technology, low toxicity and customized colors are the hallmarks of the granules.

16:9

Compound

Kunststoff Werkstoffe

Thermoplaste

Compoundeure

Dienstleistungen

Handel

Länderspecial Italien

kunststoffe-international.com

Polypropylen-Compound

Compoundieren

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

Sirmax Strengthens Business in the USA

Optics play an increasingly important role in plastic components. Glossy and even surfaces are decisive for an attractive appearance. With glass fiber-reinforced polyamides (PA), these requirements can usually only be achieved with an additional coating. A PA specially developed for surface design offers an alternative approach.

For visible components, an even, glossy surface is often desired, which is often difficult to achieve with glass fiber-reinforced PA. PA Grivory G7V from EMS now solves this problem

Aliphatic High-Performance Polyamide for Plastic Surfaces

Spritzgießen

Polyamide

Oberflächentechnik

Kunststoff

Bauwesen

Baustoffe

Faserverbundwerkstoffe

Andere Werkstoffe

Kunststofffasern

Verstärkungsstoffe

Glossy Components without Painting

Teknor Apex presents three halogen-free FR glass-reinforced polyamide compounds with UL94 ratings of V0.

Application example: engine cover in the automotive industry

Elektronik

Automotive

Technische Kunststoffe

Glass-Reinforced and Halogen-Free Flame-Retardant

Lehvoss will be coming to Fakuma with compounds for lightweight construction applications, including those intended to serve as metal substitutes.

Lehvoss will be coming to Fakuma with compounds for lightweight construction applications

Messe Fakuma

Replacing Metals with PPA Compounds

Lanxess will transfer its High Performance Materials unit to an independent legal corporate structure.

The plastics of the High Performance Materials business unit are used primarily in the automotive, electrical and electronics industries

Polybutylenterephthalat

Kunststoff-Erzeugung

Herstellung von Gummi und Kunststoffwaren

Kunststoffverarbeitung

Lanxess’ Business Unit to Become Legally Independent

A rotating mould core can induce shear in the tangential direction during injection, which superimposes the injection-induced shear. In the case of fibre-reinforced thermoplastics, this results in a reorientation of the fibres in tangential direction. This paper shows how a rotating mould core influences the fibre orientation and bursting strength of short-fibre-reinforced polypropylene and polyamide respectively. Furthermore, different wall thicknesses and fibre contents are investigated at varying rotational speeds. Regardless of the used material and the wall thickness, strength increases of more than 75 %are possible at the appropriate speed.

Schematic representation of the rotational shear rate due to the rotating tool core

Werkzeugkonstruktion

Werkzeug-, Formen- und Modellbau

Polypropylen

Influencing the fibre orientation of polypropylene and polyamide in the injection moulding process by a rotating mould core

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.

Thermoplastische Elastomere

Silikone

Messe K-Kunststoffmesse

kunststoffe.de

Masterbatches

Additive

Polyethylen

Streifinger, Florian

Polylactid

Biokunststoffe

Effektpigmente

Kunststoff-Rezyklat

Silikonkautschuk

Kautschuk / Elastomere

Is Bio the New Standard?

How can water-soluble salt cores be implemented in the composite process routes injection molding and automated fiber placement (AFP).

Slokav-Salzkern-Versuche: Vergleich umspritzter Salzkerne in der ersten Stufe: PA6 (erfolgreich) vs. CF-PEEK (fehlgeschlagen).

Polyetherketon

Werkstoffe für additive Verfahren

Towards a Robust, Water-Soluble, Lost Core Material – part one: Unreinforced, Binder-Free Salt

The new Lion stands for an extraordinary bike series. The frame and fork are made of the high-performance polymer polyamide 6 with 40 percent recycled carbon fibers.

Cool and sustainable: the new Lion Bikes for kids with frame and fork made of high-performance polymers and recycled carbon fibers.

Faserverarbeitung

Kunststoffverarbeitung: Maschinen und Komponenten

Leichtbau

Spritzgießmaschinen

Stylish, Safe and Sustainably Produced

In many technical applications, laser-sintered components still have inadequate surface topology. New methods of cost-effective and geometry-independent surface finishing of the laser-sintered specimens are therefore needed.

Fig. 1. Elastic modulus and tensile strength of PA12

 Source: University of Duisburg-Essen; graphic:  © Hanser

Influence of Chemical Post-Treatment on Glass-Filled Polyamide 12 Samples

Selektives Lasersintern von Kunststoff, Metall, Keramik

Verfahren für die additive Fertigung

Pulverbettverfahren

Additive Fertigung

Geometry-Independent Surface Finishing

PA66 and PBT considerably expand the field of applications for laser sintering by showing better properties than classic PA11 and PA12 materials in most cases.

As a temperature-resistant and flame-retardant material with high mechanical properties, PA66 opens up new application possibilities for laser sintering, such as its use as a sensor holder

PA66 and PBT for Laser Sintering

From Injection Molding to  Additive Manufacturing

To extend the range of polymer powders for selective laser sintering, Paderborn University in collaboration with the Maag Group has developed an extrusion line that can produce round particles with good flowability.

The extrusion line to manufacture powder for selective laser sintering of plastics is in the Paderborn University laboratory

Research Project to Manufacture Powder for Selective Laser Sintering of Plastics

Perfectly Round

The MERCUR research project Pr-2017–0003 „Analysis of the product development process in the combination of additive and subtractive manufacturing processes for the manufacture of multi-material products“ combines different manufacturing and post-treatment processes to connect the respective advantages.

Filamente für additive Verfahren

Investigation of the influence of various post-treatment methods on the properties of additive manufactured FDM Nylon 12 samples

A lot has changed since the first look at terahertz in Kunststoffe international [1]. Thanks to advances in system development and system integration, this technique now stands at the threshold of industrial application. The emerging application potential is now ready to be utilized for process and quality control. 

Strahlenmessgeräte

Terahertz Spectroscopy: On the Threshold of Industrial Application 

Compounding engineering focuses on rendering the compounding process more economical. Various approaches are presented for improving the economics, such as the use of more energy-efficient equipment, greater system availability and enhanced throughput. 

Aufbereitungsmaschinen

Mühlen

Mischer

Extrusion

Compounding, Recycling: Efficiency as Benchmark 

In additive manufacturing the material selection plays an important role for producing dimensionally accurate parts. Akro-Plastic developed a method to quantitatively assess warpage in additive manufacturing with pellets, which shows the influence of the material composition and the process parameters in an application-oriented manner.

Material composition in view: Compounder Akro-Plastic has developed a method for quantifying warpage in additive manufacturing.

Screw extrusion additive manufacturing with pelleted feedstocks (fused granulate fabrication, FGF) offers the possibility of producing large-format components in a short time. By using standard granulates, material costs are significantly reduced compared to filaments. At the same time, the range of printable materials is extended significantly, since materials with high filler contents of up to 60 wt. % or flame-retardant compounds can be processed as well. The FGF process allows for the extrusion of almost all polymers, however, producing dimensionally stable parts is not trivial. Due to the tendency to warp and the thermal boundary conditions during processing, the material range is limited. Unreinforced materials, for example, are subject to high warpage. In the case of high-temperature materials, the part size is often limited, or adapted processing machines are required. Semi-crystalline, reinforced plastics are particularly interesting for technical components, but are more difficult to process. Akro-Plastic investigated the influence of material composition on warpage in additive manufacturing.

In extrusion additive manufacturing, warpage occurs due to the layer-by-layer build-up and the resultant temperature and shrinkage differences. The crystallization process of semi-crystalline thermoplastics amplifies the effects. In compounds with low or without reinforcement, the part can detach from the build plate. Severe warping can lead to a collision with the extruder and thus to a failed print or to damage of machine components. Therefore, low warpage is necessary for the defect-free build-up of a dimensionally stable part (Fig. 1).

Commonly, warpage is reduced in injection molding by optimizing the process parameters. However, the mold-free process, the low pressures in the process and limited temperature control strictly limit a process-controlled warpage reduction in additive manufacturing. The use of a heated bed and build chamber to minimize warpage is state of the art in filament-based printing. However, applying this kind of temperature management is not economically feasible or even possible in FGF printing, due to the machine size and temperature limitations of machine components. Nevertheless, reinforcing the compound with fibers is a practical approach to effectively reduce warpage. Glass and carbon fibers have a low or negative coefficient of thermal expansion and therefore reduce the shrinkage potential. Furthermore, the stiffness of fiber-reinforced compounds effectively counteracts stress-induced deformation of the component.

The shrinkage of thermoplastic compounds is usually determined based on manufacturing processes. In injection molding, for example, shrinkage is determined with the help of test plates by evaluating the change of dimension relative to the mold. In contrast the final dimensions in FGF are not mold-related but predefined as machine code. Taking into account the repeatability of the traversing systems and flow fluctuations during extrusion, measuring dimensional change to determine shrinkage is not viable.

Manufacturing-Oriented Quantification of Warpage

However, the process-related evaluation of warpage is possible in FGF. One way of doing this is the evaluation of corner warp. The drawback of this method is its strong dependency on print bed adhesion. The method described below allows a quantitative comparison of different materials and the determination of a warp-index of printed test specimens using image processing.

The test specimen (Fig. 2), printed in the FGF-process is designed with trapezoidal test surfaces on three sides. To take different orientations in the build chamber into account, each side is scanned and evaluated separately. The surface structure with orientation and path of the layers is converted into a binary representation and digitally evaluated (Fig. 3). The warp-index is obtained as the deviation of the position in the z-direction of each layer in the edge areas of the test surface from the position of the respective layer in the center of the test surface. For each layer, the differences of the center line to the right edge and to the left edge are calculated as an error sum of squares and divided by the number of evaluated layers. The resulting value allows for a quantitative comparison of the warpage of different compounds within the selected process conditions.

The test specimens are printed with a nozzle diameter of 2 mm, 0.8 mm layer height and 2.5 mm layer width at a speed of 70 mm/s using a robot-guided extruder (SpaceA-1100–500-S, Yizumi Germany GmbH) without heated build plate or chamber. The influence of fiber reinforcement, glass fiber versus a recycled carbon fiber (ICF – Industrial Carbon Fiber with lower CO2 footprint compared to glass fiber), in combination with different polymers (PP, PA6, PA11), is considered. Three test specimens are printed per material and thus nine test surfaces are examined. The test specimens show bed adhesion along the entire circumference. With the corresponding unreinforced plastics, printing the test specimen is not possible.

Carbon Fiber Reduces  Warpage Effectively

The influence of the fiber material on the warpage is investigated as a function of the fiber content for PA6 (Fig. 4). In general, warpage is reduced with increasing fiber content. Carbon fibers in particular effectively reduce warpage, whereas the use of glass fibers has a minor effect. The warpage of PA6-CF30 is significantly decreased by half compared to PA6-GF30. Even in the case of similar fiber volume fraction for PA6-GF50 and PA6-CF40, the warpage of the GF-reinforced compound is more than twice as high. Increasing the carbon fiber content from 30 to 40 wt.% results in an additional 17 % reduction in warpage.

Apart from the fiber material and content, the matrix polymer is of importance. However, its effect on the warpage is less pronounced. This is demonstrated clearly for PP-CF30. Although it has a higher fiber volume fraction than PA11-CF20, the measured warpage of both materials is about the same while the warpage of the PP-CF30 is higher compared to the PA11-CF30 with similar fiber volume fraction (Fig. 5).

This observation correlates, on the one hand, with increased shrinkage due to crystallization and, on the other hand, with the stiffness of the compounds. Assuming a maximum fiber content of 20  wt. % for reinforced filaments, the warpage can be reduced by up to 37   % by further increasing the fiber content to 40  wt. % and printing with pellets. From the tested materials, PA11-CF40 (Akromid Next U28 ICF 40 1 black (8238)) showed the lowest warpage while also having a low coefficient of thermal expansion and low moisture absorption leading to high dimensional accuracy in use.

Regarding the possibilities of the FGF-process, the presented test specimen is in the lower end of range in terms of dimension and strand cross section. With increasing component size and higher extrusion volume, the warping potential becomes increasingly decisive for dimensional stability. Smaller components can be manufactured with lower fiber content (< 20 wt. %), similar to filaments. For components with dimensions in the meter range, the shrinkage-induced stresses increase accordingly, so that corner warpage becomes more likely. Higher reinforced compounds (> 30 wt. %) contribute to low-warpage production of large-format parts.

To exploit the full potential of carbon fiber-reinforced plastics and produce dimensionally stable parts, optimized processes are necessary.

The fiber orientation in the deposited strand can significantly affect the warpage and the mechanical properties of the part. It is directly influenced by the relations of extruder throughput and printing velocity as well as the proportion of bead width and nozzle diameter. Fiber orientation transverse to the deposition direction results in low strand stiffness and shrinkage compensation. Using nozzles with 1 mm and 2 mm bore diameter leads to over-extrusion of 25 % and 150 %, respectively, at a constant strand width of 2.5 mm. This results in a four times higher warp-index for the 1 mm nozzle and a clearly visible detachment of the corners from the build plate of the PA6-CF30 specimen (Fig. 6). These findings can be transferred to larger strand geometries commonly used in tool and semi-finished product manufacturing.

The method presented allows the reproducible evaluation of the warpage tendency of materials for additive manufacturing with pellets. Thus, the warping behavior can be considered in the material selection. The use of carbon fibers significantly reduces the warpage of additively manufactured parts. Additionally, CF-reinforced compounds currently offer decisive advantages over GF-reinforced compounds in processing and use. These include good surface quality combined with higher productivity and mechanical properties that enable efficient lightweight construction. A good part quality is only achieved with appropriate process settings, which can also be evaluated and optimized with the method.

Akro-Plastic GmbH  

https://www.akro-plastic.com

K.D. Feddersen GmbH & Co. KG  

https://www.kdfeddersen.com

Ausgabenartikel

3D printed: Friederike Schwartz and Michael Rieck from Akro-Plastic checking the quality of a part made of a flame-retardant compound.

Fig. 1. Warpage can already be an issue in the build process.

Fig. 2. Dimensions of the test specimen and method of evaluation.

Fig. 3. Image processing for the computer-aided evaluation of warpage.

Fig. 4. Carbon fibers reduce warpage more than glass fibers.

Fig. 5. The warping behavior can be optimized by the choice of polymer and fiber content.

Fig. 6. Fiber orientation is crucial for warpage and can be influenced via the process. 

Hauptartikel Akro-Plastic

Compounder Acro-Plastic explains how fiber reinforcement can help.

3D Printing | Plastics | Minimizes Warpage in XXL Parts

<ul><li>Friederike Schwartz, M. Sc., works as Technology Development Engineer; <a href="mailto:friederike.schwartz@akro-plastic.com">friederike.schwartz@akro-plastic.com</a></li><li>Michael Rieck, M. Sc., is Head of Innovation Management at Akro-Plastic; <a href="mailto:Michael.rieck@akro-plastic.com">Michael.rieck@akro-plastic.com</a></li></ul>