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The design of plastics profile extrusion dies becomes increasingly more complex so that conventional manufacture processes reach their limit in the die manufacture. A feasible manufacture of arbitrarily designed dies is only possible by additive manufacturing. An especially promising process is hereby the Selective Laser Melting with which metal parts with series identical mechanical properties can be produced without the need for part specific tooling or downstream sintering processes. Disadvantegeous is, however, the relatively rough surface of additively manufactured parts. Against this background, the manufacturing of an profile extrusion die by Selective Laser Melting and the plastics profile surface quality, that can be achieved with such dies, is investigated. For this purpose, profiles are extruded both with an additively manufactured die and a conventionally milled sample of the same die geometry. In case of the additively manufactured die a concept for the surface finishing of the flow channel is required, which can be applied to arbitrarily shaped geometries. Therefore, two different reworking processes are applied only to the die land of the flow channel. The comparison of the surface roughnesses shows that the additively manufactured die with a polished die land delivers the same surface quality as the conventional die.

The additive production technology selective laser melting (SLM) is used for direct fabrication of metal-based functional components. SLM is one of the powder-bed based AM technologies. SLM is well established in serial production for dental restoration as well as for tooling. Main concern for industrial application remains the scope of processible materials and resulting mechanical properties. Toward processing of aluminum alloys commercially available systems exist with comparability in terms of applied process parameters and resulting mechanical properties remaining a challenge. Often no data are available concerning process parameters and mechanical properties. This holds especially for high-power SLM systems with increased build rates as a result of extended laser powers of up to 1 kW. Especially when processing aluminum alloys, the solidification conditions significantly affect the resulting microstructure in terms of size of dendrites and grains. Consequently, the present paper systematically investigates and correlates the process parameters (e.g., laser power, scan speed, layer orientation, preheating, etc.) on the microstructure (electron backscatter diffraction and texture) and resultant mechanical properties (hardness, tensile strength, yield strength, and breaking elongation) for aluminum die-cast alloys. At this, underlying phenomena for typically observed anisotropy of mechanical properties in dependence on layer orientation are further specified.

Current results of the development of a process chain for optics manufacturing with laser radiation are presented. The process chain consists of three process steps: High Speed Laser Ablation creates the surface geometry by material ablation, Laser Polishing reduces the surface roughness by material remelting and High Precision Laser Ablation applies a form correction by removing redundant material. Compared to conventional optics manufacturing methods, this process chain benefits from its high flexibility concerning the optics geometry and its processing speed, which is independent from the processed geometry.

In this article, an innovative laser-based inline-capable coating process for the production of highly wear resistant coatings is presented. A zirconia-based sol-gel material is applied onto hardened and tempered steel substrates by a PipeJet-based printing process and spin-coating. Green films with a thickness of 100-200 nm are produced. Drying, gelation, and transformation of the green films into mechanically resistant wear protection coatings is done by laser treatments. Due to the precise temporal and spatial controllability of the diode laser radiation it is possible to generate temperatures >1000°C, required for the crystallization of the films, as well as to minimize the thermal load of the substrate. The formation of a tetragonal ZrO2 phase within the films is achieved by the laser treatment. According to finite-element calculations the temperature penetration depth of temperatures >150°C (thermal stability of the substrate around 180°C) is reduced to 20-100 µm by using pulsed diode laser radiation. The evolution of the layer thickness as well as chemical and morphological coating properties is investigated by white light interferometry, Fourier transform infrared spectroscopy, and grazing-incidence XRD measurements.

The success of laser metal deposition (LMD) for repair or fabrication of near-net shaped metals components directly from computer aided design (CAD) solid models without use of time and cost-prohibitive conventional techniques, such as five-axis milling, linear friction welding and electro chemical machining depends on the availability of a close CAD/ computer aided manufacturing (CAM) chain. Distortion and defects of a worn part implies that the nominal CAD model from the design stage is no longer suitable for the representation of the part geometry. This means that first of all the actual and the target geometry have to be constructed from which the deficit volume is determined. Only with this volume being available the tool paths can be programmed. The original data format of laser scanned data is a polygonal modelling approach for surface representation. The further step of creating a non-uniform rational B-spline (NURBS) representation of the geometry requires a major commitment in time, both in instruction and in amount of work. For this reason the Fraunhofer Institute for Laser Technology (ILT) designed a process chain for the laser material deposition (LMD) whose CAM module termed LMDCAM, is based on a polygonal modelling approach for geometry representation. NURBS are only used for the reduction of data noise in the scanned data. The target geometry of worn parts is derived by a best fit with the CAD model from the design stage. LMDCAM supports the generation of all sorts of path pattern within a layer which for example may be derived from a distortion reduction analysis. The functionalities of LMDCAM are exemplified by a repair application and the near-net fabrication of a blade-integrated disk (BLISK) blade direct from the CAD model.

Purpose - The purpose this paper is to develop an additive manufacturing (AM) technique for high-strength oxide ceramics. The process development aims at directly manufacturing fully dense ceramic freeform-components with good mechanical properties. Design/methodology/approach - The selective laser melting of the ceramic materials zirconia and alumina has been investigated experimentally. The approach followed up is to completely melt ZrO2/Al2O3 powder mixtures by a focused laser beam. In order to reduce thermally induced stresses, the ceramic is preheated to a temperature of at least 1,600 degrees C during the build up process. Findings - It is possible to manufacture ceramic objects with almost 100 percent density, without any sintering processes or any post-processing. Crack-free specimens have been manufactured that have a flexural strength of more than 500 MPa. Manufactured objects have a fine-grained two-phase microstructure consisting of tetragonal zirconia and alpha-alumina. Research limitations/implications - Future research may focus on improving the surface quality of manufactured components, solving issues related to the cold powder deposition on the preheated ceramic, further increasing the mechanical strength and transferring the technology from laboratory scale to industrial application. Practical implications - Potential applications of this technique include manufacturing individual all-ceramic dental restorations, ceramic prototypes and complex-shaped ceramic components that cannot be made by any other manufacturing technique. Originality/value - This new manufacturing technique based on melting and solidification of high-performance ceramic material has some significant advantages compared to laser sintering techniques or other manufacturing techniques relying on solid-state sintering processes.

In-stent restenosis is still an important issue and stent thrombosis is an unresolved risk after coronary intervention. Biodegradable stents would provide initial scaffolding of the stenosed segment and disappear subsequently. The additive manufacturing technology Selective Laser Melting (SLM) enables rapid, parallel, and raw material saving generation of complex 3- dimensional structures with extensive geometric freedom and is currently in use in orthopedic or dental applications. Here, SLM process parameters were adapted for poly-l-lactid acid (PLLA) and PLLA-co-poly-?-caprolactone (PCL) powders to generate degradable coronary stent prototypes. Biocompatibility of both polymers was evidenced by assessment of cell morphology and of metabolic and adhesive activity at direct and indirect contact with human coronary artery smooth muscle cells, umbilical vein endothelial cells, and endothelial progenitor cells. ?-sterilization was demonstrated to guarantee safety of SLM-processed parts. From PLLA and PCL, stent prototypes were successfully generated and post-processing by spray- and dip-coating proved to thoroughly smoothen stent surfaces. In conclusion, for the first time, biodegradable polymers and the SLM technique were combined for the manufacturing of customized biodegradable coronary artery stent prototypes. SLM is advocated for the development of biodegradable coronary PLLA and PCL stents, potentially optimized for future bifurcation applications.

This work presents a comprehensive study of the densification behavior, phase and microstructure development, hardness and wear performance of commercially pure Ti parts processed by selective laser melting (SLM). An in-depth relationship between SLM process, microstructures, properties, and metallurgical mechanisms has been established. A combination of a low scan speed and attendant high laser energy density resulted in the formation of microscopic balling phenomenon and interlayer thermal microcracks, caused by a low liquid viscosity, a long liquid lifetime, and resultant elevated thermal stress. In contrast, using a high scan speed produced the disorderly liquid solidification front and considerably large balling, due to an elevated instability of the liquid induced by Marangoni convection. A narrow, feasible process window was accordingly determined to eliminate process defects and result in full densification. The phase constitutions and microstructural characteri stics of SLM-processed Ti parts experienced a successive change on increasing the applied scan speeds: relatively coarsened lath-shaped refined acicular-shaped martensitic further refined zigzag-structured martensitic , due to the elevated thermal and kinetic undercooling and attendant solidification rate. The optimally prepared fully dense Ti parts had a very high hardness of 3.89 GPa, a reduced coefficient of friction of 0.98 and wear rate of 8.43 × 10 -4 mm 3 N -1 m -1 in dry sliding wear tests. The formation of an adherent, plastically smeared tribolayer on the worn surface contributed to the enhancement of wear performance.

Polishing of illumination optics with CO2 laser radiation - Polishing of optical components with CO2 laser radiation is a current research topic at the Fraunhofer ILT. The laser radiation is guided on the surface of the glass and due to the high absorption of the laser radiation in the material the temperature rises. The viscosity is lowered and the glass can flow. Due to the surface tension the surface is smoothened. With this polishing technique the micro roughness can be efficiently reduced in the sub-nanometer regime while the form deviation is below 1 µm for a 25 mm diameter lenses. This form deviation is sufficient for lightning applications. The micro roughness of the laser polished optics is very low so that e.g. the transmission of the optics can be increased. The processing time is with less than 10 s for a whole lens of 25 mm diameter very short compared to conventional techniques. This process is suitable for different glass materials e.g. BK7 and Floatglass. To prevent thermal damage while polishing the glass is preheated to the glass transition temperature. The glass can be annealed after to reduce thermal tensions but this is not always necessary.

Selective Laser Melting (SLM) Additive Manufacturing (AM) process was used to produce nanocrystalline TiC reinforced Ti matrix bulk-form nanocomposites. The influence of " volumetric energy density" () on densification activity, microstructural feature, nanohardness, and wear behavior of SLM-processed parts was studied. The densification levels of TiC/Ti parts remained above 97% as 120J/mm3. A further decrease in lowered the densification rate, due to the occurrence of balling effect. The TiC reinforcement experienced an interesting morphological change from the coarsened dendritic TiC (360J/mm3) to the accumulated whisker-structured TiC (180J/mm3) and to the uniformly dispersed nanoscale lamellar TiC (120J/mm3). As of 120J/mm3 was properly settled, the dynamic nanohardness (90.9GPa) and elastic modulus (256GPa) of SLM-processed TiC/Ti nanocomposites showed respectively ~22.7-fold and ~2.4-fold increase upon that of the unreinforced Ti. A uniform distribution of frict ion coefficient with a low average value

Die fortschreitende Globalisierung und die damit einhergehende Sättigung und Segmentierung der Märkte erhöht die Variantenzahl produzierender Unternehmen und verstärkt die Nachfrage an individualisierten Produkten. Um in diesem Wettbewerb bestehen zu können, setzen Unternehmen in Hochlohnländern auf eine Kombination aus individuellen und gleichzeitig qualitativ hochwertigen Produkten. Die Herausforderung besteht in diesem Zusammenhang darin, möglichst schnell auf individuelle Kundenwünsche zu reagieren und gleichzeitig die Kosten niedrig zu halten. Ein vielversprechender Ansatz dieses Problem zu lösen bietet die Technologie der generativen Fertigung, die in den letzten Jahren ihr technologisches Potenzial erheblich weiterentwickelt hat.

Das generative Fertigungsverfahren Selective Laser Melting (SLM) wird zur direkten Herstellung von metallischen Funktionsbauteilen verwendet. Während des Bauprozesses entstehen durch den schichtweisen Aufbau und die lokale Energieeinbringung mittels eines fokussierten Laserstrahls thermisch induzierte Eigenspannungen, die zu Verzug des Bauteils oder von Bauteilbereichen führen können. Üblicherweise werden die Verzüge durch Stützstrukturen zwischen Bauteil und Substratplatte verhindert. Jedoch ist es nicht immer möglich alle Bereiche eines Bauteils, je nach Komplexität der Geometrie oder Zugänglichkeit, mit Stützstrukturen zu versehen bzw. diese wieder zu entfernen. Durch eine Vorwärmung der Substratplatte während des Bauprozesses können die Verzüge reduziert oder ganz vermieden werden. Jedoch ist bisher keine systematische Untersuchung des Einflusses der Vorwärmung auf Verzüge von Aluminium Bauteilen durchgeführt worden. Ziel dieser Arbeiten ist daher die systematische Untersuchung der Auswirkung einer Vorwärmung beim SLM von Aluminiumbauteilen und die Ermittlung der geeigneten Vorwärmtemperatur, bei der nahezu keine Verzüge mehr entstehen. Eine signifikante Verzugsreduzierung im Vergleich zu den Verzügen ohne Vorwärmung zeigt sich ab einer Vorwärmtemperatur von 150°C. Bei einer Vorwärmtemperatur von 250°C sind im Rahmen der Messgenauigkeit unabhängig von der untersuchten Twincantilever Testgeometrie keine Verzüge mehr feststellbar. Neben der Reduzierung der Verzüge verhindert die Vorwärmung außerdem spannungsbedingte Risse im Bauteil, die ohne Vorwärmung zum Abreißen von Teilen der Testgeometrie führen können. Mit 90 HV 0,1 bei 250°C Vorwärmtemperatur ist die Härte größer als die geforderte Mindesthärte nach DIN EN 1706 von Druckgussbauteilen aus dem Werkstoff AlSi10Mg. Aus diesem Ergebnis kann abgeleitet werden, dass eine Vorwärmtemperatur von 250°C geeignet ist, Bauteile aus dem Werkstoff AlSi10Mg mit SLM defektfrei und prozesssicher herzustellen und Verzüge vollständig zu vermeiden.

A novel Selective Laser Melting (SLM) process was applied to prepare bulk-form TiC/Ti5Si3 in-situ composites starting from Ti/SiC powder system. The influence of the applied laser energy density on densification, microstructure, and mechanical performance of SLM-processed composite parts was studied. It showed that the uniformly dispersed TiC reinforcing phase having a unique network distribution and a submicron-scale dendritic morphology was formed as a laser energy density of 0.4 kJ/m was properly settled. The 96.9% dense SLM-processed TiC/Ti5Si3 composites had a high microhardness of 980.3HV0.2, showing more than a 3-fold increase upon that of the unreinforced Ti part. The dry sliding wear tests revealed that the TiC/Ti5Si3 composites possessed a considerably low friction coefficient of 0.2 and a reduced wear rate of 1.42 × 10- 4 mm3/Nm. The scanning electron microscope (SEM) characterization of the worn surface morphology indicated that the high wear resistance was due to the formation of adherent and strain-hardened tribolayer. The densification rate, microhardness, and wear performance generally decreased at a higher laser energy density of 0.8 kJ/m, due to the formation of thermal cracks and the significant coarsening of TiC dendritic reinforcing phase.

In this work, high-energy ball milling of a micrometre-scaled Ti and TiC powder mixture was performed to prepare TiC/Ti nanocomposites. The constituent phases and microstructural characteristics of the milled powders were studied by an x-ray diffractometer, a scanning electron microscope, an energy dispersive x-ray spectroscope and a transmission electron microscope. Formation mechanisms and theoretical basis of the microstructural development were elucidated. It showed that on increasing the applied milling time, the structures of the Ti constituent experienced a successive change from hcp (5 h) to fcc (10 h) and finally to an amorphous state (?15 h). The hydrostatic stresses caused by the excess free volume at grain boundaries were calculated to be 3.96 and 5.59 GPa for the Ti constituent in 5 and 10 h milled powders, which was responsible for the hcp to fcc polymorphic change. The amorphization of Ti constituent was due to the large defect concentration induced by severe plastic deformation during milling. The milled powder particles underwent two stages of significant refinement at 10 and 20 h during milling. For a higher milling time above 25 h, powder characteristics and chemical compositions became stable. The competitive action and the final equilibrium between the mechanisms of fracturing and cold welding accounted for the microstructural evolution. The ball milled products were typically nanocomposite powders featured by a nanocrystalline/amorphous Ti matrix reinforced with uniformly dispersed TiC nanoparticles. The finest crystalline sizes of the Ti and TiC constituents were 17.2 nm (after 10 h milling) and 13.5 nm (after 20 h milling), respectively.

Der Einsatz von Laserstrahlung eröffnet neue Möglichkeiten sowohl in der Verbesserung von Oberflächeneigenschaften als auch in der Fertigung und instandsetzung von Bauteilen. Durch eine lokale Wärmeeinbringung mit Laserstrahlung erfolgt eine gezielte Anpassung der Randschichteigenschaften an die Funktionsbeanspruchung bei gleichzeitig minimalem Verzug bzw. minimalem Wärmeeintrag in den Substratwerkstoff.

Focusing on laser additive manufacturing techniques for turbo-engine applications, two major european and german funded projects, FANTASIA and TurPro, are presented. The aim of both projects is to contribute to winning global leadership of european turbo-engine manufacturers by developing new flexible and near-net-shape additive manufacturing chains and repair techniques based on Laser Metal Deposition (LMD), as seen in Figure 1 and selective Laser Melting (SLM). This article reviews the status quo of FANTASIA and TurPro.