METE 215 MATERIALS PROCESSING LABORATORY 3D PRINTING

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1 METE 215 MATERIALS PROCESSING LABORATORY Experiment 8 Dr. Y. Eren Kalay 3D PRINTING 1. WHAT IS 3D PRINTING? Traditional manufacturing methods depend on cutting and molding technologies to create a limited number of structures and shapes having the need to be formed from a number of parts assembled together. Shaping and forming processes are performed through different stages, ranging from casting to cutting at various stages depending on the complexity of the component being manufactured. The traditional method of shaping is through material removal, which is referred to as subtractive manufacturing (SM). Examples of SM processes include milling, drilling and grinding. Manufacturing plastic and metal objects in particular is generally a wasteful process with a lot of surplus materials and chunky parts. However, Additive Manufacturing (AM) technologies transform this process by building near-net shape components one layer at a time using data from 3D CAD (computer aided design) models. These 3D models can be very complex figures, being confined only by a person s imagination with higher structural integrity and more durability. According to their first standard, ASTM F , AM is defined as The process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing technologies. Creating a similar object with the use of additive manufacturing not only utilizes less energy, but also minimizes waste. In addition to these, 3D printing helps companies save up to 70% of their manufacturing cost [1]. Creating a 3D object from a digital model using a 3D printer has been one of the largest innovations of the recent years. The idea is to build the object layer by successive layer until it is complete. Each of these printed layers is a thinly-sliced, horizontal cross-section of the eventual object. In the conventional fabrication methods, the final shape is achieved by following the steps such as cutting, extrusion, grinding and welding from a bulk structure. This sequence of processes results in loss of the original material and loss of energy during production. 3D printing technology, on the other hand, do not need any sequential steps for the final shaping and thereby it is easier to achieve new forms and optimize the shapes without being restricted by capabilities of the conventional methods. Printing begins with a digital file in which the final shape has been coded and the computer software slices the design into multilayers. These layers are then printed on top of each other until the 3D object is created. 1.1 APPLICATION AREAS As the 3D printing has become less expensive, more accessible and new materials have become available, the technology has quickly gained momentum. With the market entry of

2 compact open-source desktop 3D printers, the application areas of 3D printers have broadened from small-scale commercial or educational purposes to household use. 3D printing is most commonly used for rapid prototyping of new products. The ability to rapidly produce new prototypes for testing, often in less than 48 hours after a design revision, greatly accelerates the prototyping process. However, 3D printing technology has now reached the point when it can be applied to manufacturing processes as well. It is no surprise that first applications came from cash-rich industries, such as medical aids, aerospace and car-making. Today, the 3D printer technology is used for accessories, shoe design, industrial and architectural design, building works, defense and automotive industry, medical industry, education, aerospace industry, biotechnology is used in many areas of scientific studies in the field. 3D printed aircraft components are 65% lighter; but as strong as traditional machined parts, representing huge savings and reduced carbon emissions. For every 1 kilogram reduction in weight, airlines save around US$35,000 in fuel costs over an aircraft s life. Although expensive, titanium is light, strong and durable and ideally suited for aircraft manufacturing. In traditional manufacturing, it wears easily during cutting step of the production. This problem is eliminated via 3D printing. NASA engineers are also 3D printing parts that are structurally stronger and more reliable than conventionally crafted parts, for its space launch system [2]. Scientists are also exploring the use of 3D printers at the International Space Station to make spare parts on the spot. What once was the province of science fiction has now become a reality. 1.2 HISTORY OF 3D PRINTING The use of additive manufacturing started as in rapid prototyping (RP) during the late 1980s and early 1990s. The first commercial 3D print technology, stereolithography, was invented in 1984 by Charles Hull. Although imperfect, the machine provided manufacturing of highly complex parts overnight. The first lab grown organ is implanted in humans at the end of 1990s and this innovation opened a door for advanced medical use. The technique is mainly useful for creating artificial organs of patient-specific models, produced human tissue-compatible implants. Today, biocompatible human tissue veins that are millimeters in size are produced by 3D printers [3, 4]. Beyond the use of 3D printing in producing prosthetics and hearing aids, it is also used to treat challenging medical conditions, and to advance medical research, including in the area of regenerative medicine. The breakthroughs in this area are rapid and extraordinary. The first selective laser sintering machine became feasible in This machine uses a laser to fuse the materials into 3D products. The idea of mass customization and on-demand manufacturing of industrial parts started with this invention. Combining different raw materials isn t always possible with mass production methods due to the high costs. This problem is eliminated with the 3D printing technologies. However, additive manufacturing is relatively slower than the traditional mass production processes. In order to compensate with the slow print rate, several fused filament machines now offer multiple extruder heads. These can be used to print in multiple colors, with different polymers, or to make multiple prints simultaneously. This increases their overall print speed during multiple instance production, while requiring less capital cost than duplicate machines since they can share a single controller.

3 At the end of 2000s, 3D printers were placed on market that allows the customers to print their 3D products. Companies have created services where consumers can customize objects using simplified web based customization software and print unique objects. This now allows the consumers to create custom cases for their mobile phones, print accessories as well as many other household items. 2. TYPES OF 3D PRINTING A number of 3D printing techniques including stereolithography (SL), fused deposition modeling (FDM) and selective laser sintering (SLS). Some of these techniques involve melting or softening layers of material, others involve binding powdered materials and yet others involve jetting or selectively-hardening liquid materials. 3D printers use a variety of very different types of additive manufacturing techniques. According to the additives used in printing, 3D printing techniques can be divided into 3 groups. 2.1 BIO-BASED 3D PRINTING Recent advances in 3D printing technology have enabled tissue engineering applications in which organs and body parts are built using inkjet techniques. Biocompatible materials, cells and supporting components are printed into complex 3D functional living tissues to address the need for tissues and organs suitable for transplantation. As of 2013, scientists began printing ears, livers and kidneys with living tissue. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D bioprinted tissue models for research, drug discovery and toxicology [5]. 2.2 POLYMER BASED 3D PRINTING Today s 3D printing technology is mainly based on polymers as they can be easily processed. Polymers can be processed at low temperatures relative to metals and ceramics. The most commonly utilized polymer based composites are high performance, lightweight materials that are produced by dispersing strong additives/fibers in a polymer matrix [6]. These additives may vary from graphene to nanotubes, nanowires and nanoparticles. The additive ratio can be as low as 2% or as high as 60% depending on the application [7].

4 2.3 METALLIC BASED 3D PRINTING In metallic based 3D printing, parts are manufactured by a laser fusing together high performance metals, layer by layer directly from a 3D digital data. Created objects are strong and lightweight with complex internal features, such as undercuts, channels through sections, tubes within tubes and internal voids. It s an accurate and cost-effective method for the production of prototype components and the economical manufacture of small series parts for testing purposes or as final production components for use in many different environments, without the investment in time and money of conventional tooling. Metal 3D printing is mainly used for applications such as automotive and aerospace industry. It is predicted that the market for metal powders for additive manufacturing (AM) applications will take off over the next five years with new applications in the aerospace, oil and gas sectors, exponentially increasing the demand for powered materials [8]. In addition, metal 3D printing is also used in dental sectors for implant and prostheses manufacturing. 3. HARDWARE 3.1 FUSED FILAMENT FABRICATION (FFF) In this experiment, Fused Filament Fabrication (FFF) also known as Fused Deposition Modeling (FDM) technique will be used to produce 3D objects. In this technique, different types of materials can be used. Filaments become semi-molten state above a certain temperature to satisfy required viscosity during printing. After these filaments are deposited they immediately return their solid state. Mostly, thermoplastic polymers and copolymers are preferred as a filament such as Polylactide (PLA) and Acrylonitrile Butadiene Styrene (ABS). Because they can be melted at relatively lower temperatures compared to metals and they easily return to their solid state after deposition. These polymer filaments are deposited layer by layer. Individual layers adhere to each other during printing. Printing process has three main steps (Figure 1). In the first step, a certain amount of filament is extruded from the heater zone. Following this, the filament is heated up to a semi-molten state. Then this semi-molten filament is forced out from a heated nozzle and deposited on the predeposited layers.

5 Figure 1: Working principles of fused filament fabrication technique [9]. In this experiment, a MakerBot Replicator Mini 3D-Printer will be used. The main components of the 3D printer are shown in Figure 2. Gantry moves in X and Y direction, where build plate moves in Z direction. Figure 2: Schematic view of MakerBot Replicator Mini [10].

6 4. EXPERIMENT In this experiment, you will print a complex solid object. Please follow the following steps: Use openscad ( to draw the solid object given by your TA. Use the appropriate commands given in cheat sheet. Cheat Sheet Use slic3r ( to generate the g-code of your engineering drawing and simulate the 3D printing procedure.

7 Upload your g-code to 3D-printer and print your object. CAUTION The printer generates high temperatures. Do not try to reach inside the printer before extruder cools down. Do not try to reach inside the printer during operation. Do not look directly at the operating LED component. In case of emergency disconnect the printer from the wall socket.

8 Please Note That "The members of the METU community are reliable, responsible and honourable people who embrace only the success and recognition they deserve, and act with integrity in their use, evaluation and presentation of facts, data and documents." 1) 2) 3) Gander, K., 3D Printed Pelvis Helps Man with Rare Bone Cancer Keep Walking, The Independent Newspaper (2014,Şubat 10). 4) Laurance, J., Splint Made by 3D Printer Used to Save Baby s Life, The Independent Newspaper (2013, May 23). 5) Sean V Murphy, Anthony Atala, 3D bioprinting of tissues and organs, Nature Biotechnology, 32, (2014) 6) Keller, T., Recent all-composite and hybrid fiber reinforced polymer bridges and buildings, Prog. Struct. Eng. Mater. 3 (2001) ) Ramanathan T.,, A.A. Abdala, S. Stankovich, D.A Dikin, M. Herrera-Alonso, R.D Piner, D.H. Adamson, H.C Schniepp, X. Chen, R.S. Rouoff, S.T. Nguyen, I.A. Aksay, R.K. Prud Homme, L.C. Brinson, Functionalized graphene sheets for polymer nanocomposites, Nature Nanotechnology, 3 (2008), ) 9) Technology_Download.pdf 10) MakerBot Replicator Mini Cpmpact 3D printer Reference Guide