Fabrication of Nonplanar Surfaces Via 5-Axis 3D Printing

The advancements in manufacturing have always played a vital role in human life. One of the most recent and growing manufacturing methods is additive manufacturing (AM). AM has been in focus for its ability to manufacture intricate parts with internal features which are not possible with traditional manufacturing processes. Making parts lighter and stronger has been the goal for most AM processes. The advancements in AM have made it possible to produce parts with high strength internal structures. The overall strength of the manufactured plastic parts depends on several variables. The part’s strength is determined by the material, the build direction, the infill settings, and the printing parameters. Optimization of each of these variables is critical for obtaining the desired result for the intended application of the printed part. One of the major drawbacks of these parts is the weak interlayer bonding within parts which are susceptible to failure under high loads. Similarly, the stair stepping effect compromises the surface finish of a part. This is prominently seen when the angle of inclination is less than 30 degrees. Previous research shows that the mixture of non-planar and planar layers in a 3DP part can improve its surface finish. Non-Planar 3D printing done using a 3-axis machine is limited by the angle of the nozzle with respect to the previously printed layers. This study will focus on incorporating 5-axis 3D printer toolpath motions to print nonplanar surfaces. It will also shed some light on the enhanced mechanical properties of the parts which have non-planar layers as compared to conventionally 3D printed parts

Особливості непланарного методу 3D друку поверхонь

В статті розглядаються питання виготовлення деталей шляхом 3D друку. Наведено аналіз реалізації процесу 3D друку методами пошарового наплавлення FDM (Fused Deposition Method) і FFF (Fused Filament Fabrication) отримання прототипів. Показано шляхи вибору ефективної системи переміщення друкуючої головки процесу непланарного методу 3D друку з метою підвищення характеристик якості отриманих деталей

Development of a method of additive manufacturing by material extrusion along three-dimensional curves

© 2019, South African Institute of Industrial Engineering. All rights reserved. A method of additive manufacturing (AM) for the extrusion of material along three-dimensional curves is proposed as an alternative to conventional methods of layer-based AM for the manufacture of components designed using topology optimisation. The objectives of the study are to formulate a toolpath-generation algorithm for the extrusion process, to design the testing apparatus and methods for the validation of the proposed extrusion process, and to generate feedback based on the results obtained during testing and validation for possible implementation in topology optimisation software. The outcome of the study is a process by which toolpaths can be generated for simple geometries, and implemented using a mounted extruder serving on to a serial robot-mounted build platform

Kappaleiden 3D-tulostaminen ilman tukirakenteita

Muovia sulattavilla Fused Deposition Modeling (FDM) 3D-tulostimilla voidaan valmistaa objekteja, joilla on erittäin monimutkaisia geometrioita. Tiettyjä rajoituksia 3D-tulostettaviin geometrioihin liittyy, koska 3D-tulostimet eivät voi tulostaa materiaalia tyhjän päälle. Yleisesti ottaen 3D-tulostimilla pystyy tulostamaan 45 asteen kulmassa olevia ulkonevia rakenteita, mutta tätä suuremmilla kulmilla tulostusmateriaali alkaa valumaan ja tulostus epäonnistuu. Tallaisiin objekteihin täytyy yleensä tulostaa alle tukirakenne, jotta objekti saadaan tulostettua. Tukirakenteiden tulostaminen lisää tulostusaikaa, ja niitä saattaa olla hankala poistaa kappaleesta, kun tulostus on valmis. Tässä kandidaatintyössä tutustutaan ratkaisuihin, joilla FDM-tulostimilla pystytään tulostamaan ilman tukirakenteita kappaleita, joissa on jopa vaakatasossa olevia ulkonevia rakenteita. Mekaanisissa ratkaisuissa 3D-tulostimessa on enemmän kuin kolme liikeakselia. Tallaisia ratkaisuja ovat esimerkiksi robottikäteen asennettu tulostuspää tai neliakselinen RotBot-tulostin. Mekaanisilla ratkaisuilla voidaan tulostaa erittäin monimutkaisia rakenteita täysin ilman tukirakenteita epätasomaisen tulostuksen avulla, joka tekee tulostuskappaleista myös vahvempia. Ongelma moniakselisissa tulostimissa on se, että niiden ohjelmointi on paljon haastavampaa kuin tavallisten kolmiakselisten tulostimien ohjelmointi. G-koodipohjaiset ratkaisut toimivat normaaleilla kolmiakselisilla tulostimilla. Nämä ratkaisut perustuvat siihen, että tulostimen toimintaohje, niin kutsuttu G-koodi, muokataan sellaiseksi, että tulostuskerrokset saavat tukea edellisiltä kerroksilta eivätkä ala valumaan. Näitä ratkaisuja testataan tässä kandidaatintyössä myös käytännössä tulostamalla erilaisia testikappaleita. Ensimmäinen G-koodipohjainen ratkaisu on kartionmalliset tulostustasot. Tässä ratkaisussa kappaleet tulostetaan käyttäen kartionmallisia tulostuskerroksia tasokerrosten sijaan. Näin voidaan tulostaa jopa vaakatasossa olevia ulkonevia rakenteita täysin ilman tukirakenteita. Toinen ratkaisu on kaaritulostus, jossa ulkonevaan suuntaan tulostetaan kasvavia kaaria vierekkäin, jolloin kaaret tukevat toisiaan. Tätä ratkaisua ollaan implementoimassa käytössä oleviin slicer-ohjelmiin. Yhteenvetona voidaan sanoa, että niin mekaanisissa kuin G-koodipohjaisissa ratkaisuissa ulkonevien rakenteiden tulostamiseksi tulostimen ohjelmointi on tärkeää. Ulkonevia muotoja voidaan tulostaa tavallisella kolmiakselisella tulostimella, kunhan G-koodi on siihen sopiva.Fused Deposition Modeling (FDM) 3D-printing can be used to manufacture objects with very complex geometry. But certain limitations have to be taken into consideration when designing and printing objects. 3D-printers can’t extrude material on a thin air. Commonly 3D-printers can print overhangs in 45-degrees, but anything closer to horizontal the extruded material will start drooping down. Usually overhangs require support structure printed underneath them, but printing supports structures takes time and material. This thesis will investigate solutions to print overhanging structures without supports on an FDM-printers. On mechanical solutions there are more than three movement axels on the printer. For example, FDM-printhead attached to a robot arm or four axes RotBot-printer. With mechanical solutions it is possible to print very complex structures without supports, because with more axels, printer can print objects in any rotation. Objects can also be printed with non-planar shells, instead of stacking X-Y-planes in Z-direction. Objects printed in non-planar way would also be much stronger compared to normally printed parts. The problem with mechanical solutions is that they are much harder to program. Crating G-code for a robot arm or multi axel printer is harder and usually requires special software. G-code based solutions for printing overhangs work well on a normal three axel printers. In these solutions print instructions for the machines, so called G-code, is altered such a way that printers can print even horizontal overhangs without any support structures. In this thesis these solutions are tested by printing various test objects. First solution is to print cone shaped shells, instead of X-Y-layers. This solution is originally for RotBot-printer, but it works with ordinary printers as well, but printhead geometry has to be taken into consideration when printing non-planar shells. The other solution is to print arcs that grow from the center. In this solution only the overhanging plane has to be special, rest of the object can be printed using normally sliced G-code. This solution is relatively easy to code, and 3D-printing community has already started to implement it to slicer-softwares. Conclusion: Printing overhangs without support structures is not mechanically very challenging. It can be done with robot arms and multi axel printers, but also with normal three axel printers. The difficult part of printing overhangs without support structures is creating G-code for that purpose

Machine Learning for Additive Manufacturing

Additive manufacturing (AM) is the name given to a family of manufacturing processes where materials are joined to make parts from 3D modelling data, generally in a layer-upon-layer manner. AM is rapidly increasing in industrial adoption for the manufacture of end-use parts, which is therefore pushing for the maturation of design, process, and production techniques. Machine learning (ML) is a branch of artificial intelligence concerned with training programs to self-improve and has applications in a wide range of areas, such as computer vision, prediction, and information retrieval. Many of the problems facing AM can be categorised into one or more of these application areas. Studies have shown ML techniques to be effective in improving AM design, process, and production but there are limited industrial case studies to support further development of these techniques

CurviSlicer: Slightly curved slicing for 3-axis printers

International audienceMost additive manufacturing processes fabricate objects by stacking planar layers of solidified material. As a result, produced parts exhibit a so-called staircase effect, which results from sampling slanted surfaces with parallel planes. Using thinner slices reduces this effect, but it always remains visible where layers almost align with the input surfaces. In this research we exploit the ability of some additive manufacturing processes to deposit material slightly out of plane to dramatically reduce these artifacts. We focus in particular on the widespread Fused Filament Fabrication (FFF) technology, since most printers in this category can deposit along slightly curved paths, under deposition slope and thickness constraints. Our algorithm curves the layers, making them either follow the natural slope of the input surface or on the contrary, make them intersect the surfaces at a steeper angle thereby improving the sampling quality. Rather than directly computing curved layers, our algorithm optimizes for a deformation of the model which is then sliced with a standard planar approach. We demonstrate that this approach enables us to encode all fabrication constraints , including the guarantee of generating collision-free toolpaths, in a convex optimization that can be solved using a QP solver. We produce a variety of models and compare print quality between curved deposition and planar slicing

Additive manufacturing using robotic manipulators, FDM, and aerosol jet printers.

Additive manufacturing has created countless new opportunities for fabrication of devices in the past few years. Advances in additive manufacturing continue to change the way that many devices are fabricated by simplifying processes and often lowering cost. Fused deposition modeling (FDM) is the most common form of 3D printing. It is a well-developed process that can print various plastic materials into three-dimensional structures. This technology is used in a lot of industries for rapid prototyping and sometimes small batch manufacturing. It is very inexpensive, and a prototype can be created in a few hours, rather than days. This is useful for testing dimensions of designs without wasting time and money. Recently, a new form of additive manufacturing was developed known as aerosol jet printing (AJP). This process uses a specially developed ink with a low viscosity to print a wide range of metals and polymers. These printers work by atomizing the ink into a mist that is pushed out of a nozzle into a focused beam. This beam deposits material on the substrate at a standoff distance of 3-5 mm. Since this is a non-contact printing process, many non-planar surfaces can be printed on quite easily. AJP also offers very small feature sizes as low as 30 µm. It is useful for printing conductive traces and printing on unique surfaces. These printed traces often need some form of post processing to fully cure the ink and remove any solvent. For metals such as silver, this post processing removes solvent, increases conductivity, and increases adhesion. Methods for post processing include using an oven, intense pulse light (IPL), or a laser that follows the traces as they are printed. Of these methods, the IPL offers the greatest flexibility because it can cure a larger area than the laser and only takes a few seconds compared to hours in an oven. In this thesis, these two types of additive manufacturing processes, FDM and AJP, are explored, developed, and integrated with robotic manipulators in a custom system called the “Nexus”. By integrating these processes with robotic manipulators, these processes can be automated and combined to create unique processes and streamlined fabrication. The third chapter covers the development of the AJP printing and curing processes and integration with the Nexus system as well as some example devices such as a strain gauge. The fourth chapter goes over how a custom FDM module was integrated into the Nexus system and how material extrusion is synchronized with the motion component. Finally, in the second part of the fourth chapter, an FDM 3D printer is designed and fabricated as an end effector for a 6DOF robotic arm to be used in the Nexus system. To control these processes, G-Code is used to tell the machines the correct path to take. Methods for generating 5-axis G-Code are suggested to enable non-planar printing in the future