Design and fabrication of conformal cooling channels in molds:Review and progress updates

Conformal cooling (CC) channels are a series of cooling channels that are equidistant from the mold cavity surfaces. CC systems show great promise to substitute conventional straight-drilled cooling systems as the former can provide more uniform and efficient cooling effects and thus improve the production quality and efficiency significantly. Although the design and manufacturing of CC systems are getting increasing attention, a comprehensive and systematic classification, comparison, and evaluation are still missing. The design, manufacturing, and applications of CC channels are reviewed and evaluated systematically and comprehensively in this review paper. To achieve a uniform and rapid cooling, some key design parameters of CC channels related to shape, size, and location of the channel have to be calculated and chosen carefully taking into account the cooling performance, mechanical strength, and coolant pressure drop. CC layouts are classified into eight types. The basic type, more complex types, and hybrid straight-drilled-CC molds are suitable for simply-shaped parts, complex-shaped parts, and locally complex parts, respectively. By using CC channels, the cycle time can be reduced up to 70%, and the shape deviations can be improved significantly. Epoxy casting and L-PBF show the best applicability to Al-epoxy molds and metal molds, respectively, because of the high forming flexibility and fidelity. Meanwhile, LPD has an exclusive advantage to fabricate multi-materials molds although it cannot print overhang regions directly. Hybrid L-PBF/CNC milling pointed out the future direction for the fabrication of high dimensional-accuracy CC molds, although there is still a long way to reduce the cost and raise efficiency. CC molds are expected to substitute straight-drilled cooling molds in the future, as it can significantly improve part quality, raise production rate and reduce production cost. In addition to this, the use of CC channels can be expanded to some advanced products that require high-performance self-cooling, such as gas turbine engines, photoinjectors and gears, improving working conditions and extending lifetime

Design optimization of conformal cooling channels for injection molds: 3D transient heat transfer analysis

This research aims to enhance the design of an injection mold in order to minimize ejection time and increase temperature uniformity by repositioning cooling channels. For 3D transient thermal simulations, the ANSYS finite element method (FEM) program was employed, while the MATLAB program was used for optimization. It was discovered that the method could be used successfully to optimize the design of Conformal Cooling Channels (CCCs) in injection molds. The objective function value of the optimized model represents a near 40% improvement in relation to the initial model. The combined parameterization, simulation, and optimization method has proven beneficial for enhancing the arrangement of channels in an injection machine mold. The methodology is generalizable. As such, it can be employed in any industrial applications involving injection molding machines, for the improvement of the quality of the manufactured part.PORTUGAL 2020 Partnership Agreement, through the European Social Fund (ESF) European Regional Development Fund, by the Operational Programme "Competitiveness and Internationalization”, in the scope of “Portugal 2020”.European Regional Development Fund, by the Operational Programme "Competitiveness and Internationalization”, in the scope of “Portugal 2020”

Surface Finish Control of 3D Printed Metal Tooling

Solid freeform fabrication (SFF) technology has shown a great deal of promise for the plastic injection molding industry due to its ability to produce complex geometry tooling relatively quickly. However, one shortcoming of metal-based SFF processes is that they have difficulty producing parts with acceptable surface quality. As such, secondary operations, such as machining, are frequently required thereby increasing fabrication time and cost. In addition, there is variation in the surface quality that is dependent upon the surface orientation during the build process. For example, parts produced using the metal-based 3-D printing process have vertical faces with a typical roughness 50% greater than the horizontal faces. This work investigates surface finish improvement techniques used with 3D printed metal parts during the infiltration treatment. The goal is to produce injection mold tooling with an acceptable surface quality without performing a secondary machining process. By extending the infiltration cycle and applying a planar contact surface to the face of a sample, reductions in roughness of up to 83% were achieved. Such a surface would be categorized as a D-series surface under the surface finish standards for injection molding. The optimal condition for roughness reduction is to use a horizontally oriented printed face with a polished quartz blank applied during an extended infiltration cycle. This study determined that the use of contact pressure does not have a clear and significant effect on roughness

Tekes projekti SuperMachines loppuraportti

Tutkimuksessa kerättiin best practice aineistoa ja kehitettiin internet alusta kerätyn aineiston tutkimiseen ja hakujen suorittamiseen. Aineisto löytyy internet osoitteesta: http://www.amcase.info/. Rekisteröitymällä kuka vain voi syöttää alustalle lisää aineistoa. Kappaleiden suunnitteluohjeet on julkaistu Suomen pikavalmistusyhdistyksen sivuilla: http://firpa.fi/html/am-tietoa.html. Ohjeesta löytyy mm. suositeltu minimi seinämänvahvuus, suositellun pienimmän yksityiskohdan koko, tyypillinen markkinoilta löytyvä rakennuskammin koko, sekä tyypilliset materiaalit. Valmiiden kokoonpanojen ja mekanismien suunnitteluun muodostettiin Objet 30 ja UPrint SE+ laitteelle ohjeistus josta löytyy pienin radiaalinen välys, aksiaalinen välys, sekä pienin rako riippuen rakennussuunnasta. Tutkimusprojektin aikana seurattiin alan teknologian kehitystä. Kahden vuoden aikana markkinoille ilmaantui noin. 50 uutta laitevalmistajaa, sekä noin 300 erilaista laitetta, sekä lukuisia materiaaleja. Merkittävimmät uudistukset listattiin ja pohdittiin mahdollisia kehityssuuntia. Kaikki uudet toimijat ja laitteet päivitettiin Firpan ylläpitämään tietokantaan: http://firpa.fi/html/am-tietoa.html. Markkinoilla on selvä suuntaus tuotantokomponenttien valmistamiseen, kotitulostimien hintojen laskemiseen, sekä isompien kappaleiden valmistamiseen. Muovilevy komponenttien muovaamista tutkittiin laserin ja alipaineen avulla DDShape laitteella. Laitteella onnistuttiin tekemään testikappaleita ja laitetta saatiin kehitettyä eteenpäin. Laitteiston kehittämiseksi ja kaupallistamisen tueksi Tekes on myöntänyt "Tutkimusideoista uutta tietoa ja liiketoimintaa" (TUTLI) rahoituksen. ISF mini projektissa onnistuttiin kehittämään edullinen pienten kappaleiden painomuovauskone. Samalla kartoitettiin laitteelle soveltuvat parametrit ja rajoitukset. Laseravusteisella muovaamisella päästään kuparilla isompaan seinämän kaltevuuteen ja pinnalaatu pysyy hyvänä. Teräksellä laserista ei ollut juuri hyötyä ja alumiinilla muovattavuus kyllä parani, mutta pinnalaatu huononi. AM kappaleiden viimeistelykoneistuksessa tutkittiin muovisten kappaleiden viimeistely jyrsimällä, sekä metallikappaleiden automaattista hiontaa. Jyrsinnässä vertailtiin eri menetelmillä tehtyjä kappaleita, sekä mitattiin kappaleiden mittatarkkuutta ja geometrisia toleransseja. Huonosta kotitulostimella tehdystä kappaleesta on vaikea saada hyvää kappaletta vaikka se viimeisteltäisiin koneistamalla. Suurimmat ongelmat liittyvät kappaleiden vääntymiseen johtuen lämpöjännityksistä valmistusprosessin aikana. Kappaleiden automaattisessa hionnassa parhaat tulokset saatiin DMLS kappaleille käyttämällä hionta-aineena teräshauleja ja pyörittämällä niitä hiottavat kappaleen kanssa rummussa. Ra arvo parani tällöin noin seitsemästä mikrometristä kolmeen mikrometriin

Development and initial results for roller-deposition metal powder bed laser fusion additive manufacturing

The process of metal additive manufacturing is becoming increasingly economically viable over traditional subtractive manufacturing processes. However, due to the infancy of the technology, there is a lack of documentation on how to rapidly and efficiently design and fabricate a given part. Our research at Iowa State University aims to aid in the discovery and communication of knowledge on the process as well as increase industry understanding of the modern additive process. Initial focus will be in support structures, as the technology requires a connection between a part and the base plate. This report will give an introduction as well as cover the key understanding and developments with support structures for metal additive manufacturing. A large volume of work has been completed during this research in collaboration with industries around Iowa. Many unique projects and designs have been fabricated utilizing this technology, each with their own unique challenge and outcome. This paper will discuss much of the work completed with these companies around design for additive, and the volume of new insights gained from each project

Additively manufactured permeable-dense composites and its applications in microstructured reactors

Die additive Fertigung (auch als 3D-Druck bekannt) ist eine neuartige Fertigungstechnologie, mit der Objekte gemäß einem 3D-Modell aus formlosem Material schichtweise aufgebaut werden können. Das Laserstrahl-Pulverbettschmelzen (Laser Beam Powder Bed Fusion, LB-PBF) ist ein wichtiges Verfahren der additiven Fertigung für metallische Werkstoffe, das mittlerweile in zahlreichen Branchen weit verbreitet ist. Biomedizinische Implantate mit komplexen Porenstrukturen werden häufig mittels LB-PBF hergestellt. Diese Porenstrukturen werden normalerweise in einem CAD-Modell entworfen, so dass man von geometrisch definierter Gitterstrukturporosität (GDLSP) spricht. Die Porengröße von durch GDLSP hergestellten porösen Materialien ist jedoch häufig größer als 100 µm. Eine andere Art von 3D-gedrucktem porösem Material wird als Material mit geometrisch undefinierter Porosität (GUP) bezeichnet. Die Porenstrukturen von GUP-Materialien werden durch Variation der Parameter des LB-PBF-Verfahrens gesteuert und die Porengröße liegt im Bereich von 1 µm bis 100 µm. Aufgrund der im Vergleich zu GDLSP-Materialien geringeren Porengröße und der Möglichkeit in einem Arbeitsgang poröse Bereiche mit unporösen Bereichen in einem Bauteil zu verbinden besteht ein zunehmendes Interesse an GUP-Materialien. In dieser Dissertation wurde die Beziehung zwischen den Parametern des LB-PBF-Verfahrens wie Schraffurabstand, Laserfokusdurchmesser und Scanstrategie und den resultierenden porösen Struktureigenschaften systematisch untersucht. Die experimentellen Ergebnisse zeigen, dass das GUP-Material zwei Arten von Poren enthält. Die Poren innerhalb der Laserspuren sind größer und instabil. Die Poren zwischen den Laserspuren können leicht durch die Laserparameter gesteuert werden. Wenn der Schraffurabstand zunimmt, nehmen Porosität, Porengröße, Permeabilität und Oberflächenrauigkeit zu. Wenn der Laserfokusdurchmesser zunimmt, ändert sich die Porosität nicht wesentlich, die Rauigkeit nimmt zu, Porengröße und Permeabilität nehmen ab. Der entscheidende Punkt ist das Balling-Phänomen. Eine größerer Laserfokusdurchmesser führt zu mehr Pulver, das auf der porösen Oberfläche versintert wird. Die Wirkung verschiedener Scanstrategien, einschließlich unidirektionaler Scanvektoren (USV), Rotations-Scanvektoren (RSV) und Vier-Richtungs-Scanvektoren (FDSV) auf die Oberflächenmorphologie wurde auf rohrförmigen Proben untersucht. Basierend auf dem 3D-gedruckten porösen Material wurden porös-dichte Verbundbauteile gedruckt. Ein Testmodul auf dieser Basis wurde für die nachfolgende Beschichtung mit einer permeablen keramischen Zwischenschicht vorbereitet. Ein 2 mm dickes Testmodul wurde dazu mit einer Fräsmaschine geglättet. Die Rauigkeit des geglätteten Testmoduls beträgt 1,36 µm, was das Potenzial als neuartiges Membransubstrat zeigt. Ferner wurden poröse Membransubstratplatten (PMS-Platten) und poröse Membransubstratrohre (PMS-Rohre) für Mikroreaktoren hergestellt. In der Forschung lässt sich ein zunehmendes Interesse an 3D-gedruckten mikrostrukturierten Apparaten für verfahrenstechnische Anwendungen beobachten. Für die Herstellung von 3D-gedruckten Mikroreaktoren wurde eine 90 ° - Designstrategie und eine 45 ° - Druckstrategie vorgeschlagen. Mikroreaktoren mit Temperatursperrmodul und internen Kanälen wurden als beispielhafte Anwendung konzipiert und gedruckt

Towards Fully Additively-Manufactured Permanent Magnet Synchronous Machines: Opportunities and Challenges

With the growing interest in electrification and as hybrid and pure electric powertrains are adopted in more applications, electrical machine design is facing challenges in terms of meeting very demanding performance metrics for example high specific power, harsh environments, etc. This provides clear motivation to explore the impact of advanced materials and manufacturing on the performance of electrical machines. This paper provides an overview of additive manufacturing (AM) approaches that can be used for constructing permanent magnet (PM) machines, with a specific focus on additively-manufactured iron core, winding, insulation, PM as well as cooling systems. Since there has only been a few attempts so far to explore AM in electrical machines (especially when it comes to fully additively-manufactured machines), the benefits and challenges of AM have not been comprehensively understood. In this regard, this paper offers a detailed comparison of multiple multi-material AM methods, showing not only the possibility of fully additively-manufactured PM machines but also the potential significant improvements in their mechanical, electromagnetic and thermal properties. The paper will provide a comprehensive discussion of opportunities and challenges of AM in the context of electrical machines

Metal Additive Manufacturing – State of the Art 2020

Additive Manufacturing (AM), more popularly known as 3D printing, is transforming the industry. AM of metal components with virtually no geometric limitations has enabled new product design options and opportunities, increased product performance, shorter cycle time in part production, total cost reduction, shortened lead time, improved material efficiency, more sustainable products and processes, full circularity in the economy, and new revenue streams. This Special Issue of Metals gives an up-to-date account of the state of the art in AM

A Guide to Additive Manufacturing

This open access book gives both a theoretical and practical overview of several important aspects of additive manufacturing (AM). It is written in an educative style to enable the reader to understand and apply the material. It begins with an introduction to AM technologies and the general workflow, as well as an overview of the current standards within AM. In the following chapter, a more in-depth description is given of design optimization and simulation for AM in polymers and metals, including practical guidelines for topology optimization and the use of lattice structures. Special attention is also given to the economics of AM and when the technology offers a benefit compared to conventional manufacturing processes. This is followed by a chapter with practical insights into how AM materials and processing parameters are developed for both material extrusion and powder bed fusion. The final chapter describes functionally graded AM in various materials and technologies. Throughout the book, a large number of industrial applications are described to exemplify the benefits of AM

3D integration of micro- and nanostructures into bio-analytical devices

This study aims to develop a process which allows 3D integration of micro and nanostructures in microchannels. A fabrication process was established for the large area integration of hierarchical micro and nanostructures in microchannels. This novel process, which is called 3D molding, takes advantage of an intermediate thin flexible stamp such as PDMS from soft lithography and a hard mold such as brass from hot embossing process. However, the use of a thin intermediate polydimethylsiloxane (PDMS) stamp inevitably causes dimensional changes in the 3D molded channel, with respect to those in the brass mold protrusion and the intermediate PDMS stamp structures. We have investigated the deformation behavior of the 3D molded poly(methyl methacrylate) (PMMA) substrate and the intermediate PDMS stamp in 3D molding through both experimentation and numerical simulation. It was found that for high aspect ratio brass mold protrusion, the maximum strain of the intermediate layer occurs in the bottom center of the 3D channels. However, with decreasing the aspect ratio of brass mold protrusion the highest elongation occurs at the bottom corners of the channel causing less elongation of the intermediate PDMS stamp and imprinted structures on the bottom surface of the 3D channel. A modified 3D molding process which is called 3D nanomolding is developed which allows nanopatterning the surface of small microfeatures. Using 3D nanomolding process and solvent assisted bonding microdevices with no side, one side, three sides and four sides patterned were fabricated. To characterize 3D flow patterns induced by the surface structures on microdevices, confocal microscopy was used as dyed water and undyed water injected from separate inlets of micromixer were mixed along the microchannel at flow rates of 10 and 40 μL/min. The standard deviation of the normalized intensity measured in the confocal image of the cross section of the channel was used for quantifying the degree of mixing and evaluating the mixing performance of all four different microdevices. Experimental and simulation results show that by patterning the surface of the micromixer, flow patterns can be manipulated, which can improve mixing through stretching and folding of fluid elements and therefore increasing the interfacial area between fluids and cutting down the diffusion length. The effect of increasing velocity on increasing standard deviation (decreasing mixing) was also found to be less for the micromixers whose surfaces are patterned compared to the plain channel