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78 views31 pages

Additive MFG Presentation PDF

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Semester VII — Mechanical Engineering ADVANCED MANUFACTURING PROCESS Additive Manufacturing Processes badebhandd@igmail.com Mo.9673714743 Shri Swami Samarth *SYLLASBUS : Introduction and prineiples, Development of additive manufacturing Technologies, general additive manufacturing processes, powder based fusion process, extrusion based system, sheet lamination process, direct write technologies. INTRODUCTION : Additive Manufacturing (AM) technology came about as a result of developments ina variety of different technology sectors. Like with rhany)manufacturing technologies, improvements in computing power and reduction in mass storage”Gasts paved the way for processing the large amounts of data typical of modern 3D Computer-Aided Design (CAD) models: within reasonable time frames, Nowadays, we'have becomelquite’accustomed to having powerful ‘computers and other complex automated machines around us and sometimes it may be difficult for tus to imagine how the pioneers struggled to develop the first AM machines, 3D printing also known as additive manu facturing is any of various pracesses used to make a three-dimensional object, [n 3D printing, additive processes are used, in which successive layers ‘of material are laid down undef:computer control, These objects can be of almost any shape or geometry, and are produced. from @3D model or other electronic data source, A 3D printer isa type of industrial robot, Additive Manufacturing refers to process by Which digital 3D design data is used to- build up.a component in layers by depositing material, The term "3D printing” is inereasingly used asa synonym for Additive Manufacturing. However, the latter is more accurate in that it describes 44 professional production technique which is clearly distinguished from conventional methods of material removal. Instcad of milling a work piece from solid block, for example, Additive Manufaeturing builds up components layer by layer using materials which are available in fine powder form material. A range of different metals, plastics and composite materials may be used, The technology has especially been applied in conjunction with Rapid Prototyping (industries markets /rapid prototyping) - the construction of illustrative and functional prototypes Additive Manufacturing is now being used increasingly in Series Production. It gives Original Equipment Manufacturers (OEMs) in the most varied seetors of industry (industries markets) the ‘opportunity to create a distinctive profile for themselves based on new customer benefits, cost- saving potential and the ability to meet sustainability goa (badehhaudaigmall com SND COE & RC-Yeota, Mo.96 73714743 > FUNCTIONAL PRINCIPLE. ‘The sysiem starts by applying a thin layer of the powder materia to the building platform, A powerful laser beam then fuses the powder at exactly the point's defined by the comput ‘generated component design data, The platform is then lowered and another layer of powder is applied, Once again the material is fused so as to bond with the layer below al the predefined points. Depending on the material used, components can be manufactured using stereo lithography laser sintering or 3D printing, ® Development of Additive Manufacturing Technology Like many other technologies»AM came about as a result of the invention of the computer. AM takes full advantage of many of the important features of computer techno- logy, both di (in the AM machines themselves) and indirectly (within the supporting technology), including *Procéssing power: Part data files can be very large and require a reasonable amount of processing power to manipulate while setting up the machine and when slicing the data before building: Earlier machines would have had difficulty handling large CAD data files, *Graphies capability: AM machine operation does not require a big graphics engine except to see the file while positioning within the virtual machine space. However, all machines benefit from a good graphical user interface (GUI) that ean make the machine easier to set up, operate, and maintain, *Machine control: AM technology requires precise positioning of equipment ina a Computer Numerical Controlled (CNC) machining center, or even a highend photocopy Tpadebharudigmall. com SND COE & RC.Yeota. Mo,9673714743 machine or laser printer. Such equipment requires controllers that take for determining status and actuators for positioning and other output functions. Ce generally required in order to determine the control requirements. Conducting these control tasks ‘event in real-time docs not normally require significant amounts of processing power by today’s standards, Dedicated functions like positioning of motors, lenses, etc. would normally require individual controller modules, A computer would be used to oversee the communication to and from these controllers and pass data related to the part build function. *Networking: Nearly every computer these days has a method for communicating with other ‘computers around the world. Files for building would normally be designed on‘another computer to that running the AM machine, Earlier systems would have required the files to be Toaded from disk or tape, Nowadays almost all files will be sent using an Ethernet eonneetion, often via the Internet. “Integration; As is indicated by the variety of functions, the computer forms a Géntral component that ties different processes together. The purpose of the computer would be to communicate with ‘other parts of the system, to process data, and to send that data fromyone pant of the system to the ‘other, Figure, shows how the above mentioned technologies are integrated to form an AM machine, Asians ] | ees = Figure.1 General integration of an AM mi badehheuda gmail.com SND COE & RC.Yeota. Mo,9673714743 Without computers there would be ne capability 1 display 3D graphic images, Without 3D: graphics, there would be no Computer-Aided Design. Without this ability to represent objects digitally in 3D, we would have a limited desire to use machines to fabricate anything but the simplest shapes. It is safe to say, therefore, that without the computers we have today, we would not have seen Additive Manufacturing develop. Additive Manufacturing technology primarily makes use of the output from mechanical engineering, 3D Solid Modeling CAD oftware. It is important to understand that this is only a branch of a much larger set of CAD systems and, therefore, not all CAD systems will produce output suitable for layer-basedAM technology. Currently, AM technology focuses on reproducing geometric form; and sorthe better CAD systems to use are those that produce such forms in the most precise and effective wa NC machining, therefore, only requires surface modeling software, All carly:CAM systems were based on surlace modeling CAD. AM technology was the first automated computer-aided manufacturing process that truly required 3D solid modeling: CAD, It was necessary to havea fully enclosed surface ta generate the driving coordinates for AM. This'ean be achieved using surface inodeling systems, but because surfaces are described by boundary eurves it is often difficult to precisely and seamlessly connect these together. Even iPthe gaps are imperceptible, the resulting models may be difficult to build using AML/At the very leasty/any inaccuracies in the 3D model would be passed on to the AM part that Was constructed, Early AM applications often displayed difficulties because of associated problems with surface modeling software. Since itis important for AM systems to have aécurate models that are fully enclosed, the preference is forsolid modeling CAD. Solid madeling CAD ensures that all models made have a volume and, therefore, by definition are fully enclosed. surfaces, While surfitce modeling can be used in part construction, we can nét always'be Sure that the final model is faithfully represented as a s Such models are generally Aecessary for Computer-Aided Engineering (CAE) tools like Finite Element Analysis (FEA), but are alsa very important for other CAM processes, “> ADDITIVE MANUFACTURING PROCESSES ‘The Powder Bed Fusion process includes the following commonly used printing techniques: Direct metal laser sintering (DML), Electron beam melting (EBM), Selective heat simering (SHS), Selective laser melting (SLM) and Seleetive laser sintering (SLS),Powder bed. fusion (PBF) methods use either a laser or electron beam to melt and fuse material powder together, ectron heam melting (EBM), methods require a vacuum but can be used with metals and alloys in the creation of functional parts, All PBF processes invalve the spreading of the powder material ‘over previous layers, There are different mechanisms to enable this, including a roller of a blade, A hopper or a reservoir below of aside the bed provides fresh material supply. Direet metal laser badebhcusiigenall com SND COE & RC.Yeota. Mo.96 73714743 sintering (DMLS) isthe same as SLS, but with the use of metals and not plastics. The process sinters the powder, layer by layer. Selective Heat Sintering differs trom other processes by way of using a heated thermal print head to fuse powder material together. As before, layers are added with a roller in between fusion of layers. A platform lowers the model accordingly. The technique fuses parts of thestayer, and then moves the working area downwards, adding another layer of granules and repeating the process until the piece has built up. ‘This process uses the unfused media to support overhangs and thin walls in the part g produced, which reduces the need for temporary auxiliary supports for the piece, A laser is typically used to sinter the media into a solid, Inert gas Powder chamber Fige2 Powder bed fusion process * Powder Bed Fusion ~ Step by Step 1. A layer, typically 0.1mm thick of material is spread over the build platform, 2. A laser flases the first layer or first cross section of the model. Tbadebharudgmall.com SND COE & RC.Yeota, Mo,9673714243 3. A new layer of powder is spread across the previous layer tsing.a roller. 4, Further layers or eross sections are fused and added, 5. The process repeats until the entire model is created, Loose, unfuised powder is remains in position but is removed during post processing. In powder bed fusion, particles of material (e.g., plastic, metal) are selectively fused together using a thermal energy source such as a laser. Once a layer is fused, a new/one is created ‘by spreading powder over the top of the object and repeating the process, Unfused material is used to support the object being produced, thus reducing the need for support systems: Selective laser sintering (SLS) is the first among many similar processes like Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM) and laser cusing, SL$ can be defined as powder bed fusion process used to produce objects from powdered materials using one or more lasers to selectively fuse or melt the particles at the surfice, layer by/layer, in an enclosed chamber, SLM is an advanced form of the SLS process where, full melting of the powder bed particles takes. place by using one or more lasers, Build piston Build platform . Powder dispenser piston Powder dispenser platform ta poor Metal powder supply sesh Recoater arm Laser Lenses Laser beam Sintered part Powder bed XY scanning, mirror Asoatec am Pounier chypenset ‘patter Fig. Laser based powder hed fusion technology Lasef using is similar to SLM process where laser is used to fuse cach powder bed layer as per required cross section to build the complete part in the enclosed chamber. The term laser

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