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Application and Architecture Survey on 3D Printing
1Venugopal B S, 2Bhoopendra R, 3Vivek M Karigar, 4Kiran R, 5B N Sathyanarayana Reddy
1,2,3,4,5Dept. of Mechanical Engineering, R.R. Institute of Technology, Bangalore, India.
Abstract— Additive manufacturing is often referred as 3D printing which has the potential to swiftly accelerate innovation, minimize materials, energy usage and compress supply chain.3D printing is a new way of printing a product and components from a digital model. It creates components by depositing thin layers of material one after another using a digital blueprint until the exact or accurate component has been created. Interest in additive techniques is increasing as applications of 3D printing have progressed from rapid prototyping to the production of end-use products. It uses materials like metals, composites, polymers or other powders to print a range of functional components. The applications of 3D printing potentially benefits a wide range of industries including defense, aerospace, automotive, biomedical and consumer products.
Index terms— Additive manufacturing,3D Printing, Architecture, Printing layers, Applications.
I. INTRODUCTION
3D printing or additive manufacturing (AM) is any of various processes for making a three-dimensional object of almost any shape from a 3D model or other electronic data source primarily through additive processes in which successive layers of material are laid down under computer control. A 3D printer is a type of industrial robot.
Early AM equipment and materials were developed in the 1980s. In 1984, Chuck Hull of 3D Systems Corp invented a process known as stereo lithography employing UV lasers to cure photopolymers. Hull also developed the STL file format widely accepted by 3D printing software, as well as the digital slicing and infill strategies common to many processes today. Also during the 1980s, the metal sintering forms of AM were being developed (such as selective laser sintering and direct metal laser sintering), although they were not yet called 3D printing or AM at the time. In 1990, the plastic extrusion technology most widely associated with the term “3D printing” was commercialized by Stratasys under the name fused deposition modeling (FDM). In 1995, Z Corporation commercialized an MIT-developed additive process under the trademark 3D printing (3DP), referring at that time to a proprietary process inkjet deposition of liquid binder on powder.
AM technologies found applications starting in the 1980s in product development, data visualization, rapid prototyping, and specialized manufacturing.
Their expansion into production (job production, mass production, and distributed manufacturing) has been under development in the decades since. Industrial production roles within the metalworking industries achieved significant scale for the first time in the early 2010s. Since the start of the 21st century there has been a large growth in the sales of AM machines, and their price has dropped substantially.
According to Wohler’s Associates, a consultancy, the market for 3D printers and services was worth $2.2 billion worldwide in 2012, up 29% from 2011.
Applications are many, including architecture, construction (AEC), industrial design, automotive, aerospace, military, engineering, dental and medical industries, biotech (human tissue replacement), fashion, footwear, jewellery, eyewear, education, geographic information systems, food, and many other fields.
ARCHITECTURE
Fig1: Architecture of Printer
The picture shows the structure of a typical 3D printer.
The print table is the platform where the objects for printing has been situated. It provides the basic support for manufacturing objects layer by layer.
The extruder is the most important part of a 3D-Printer.
As the extruders in the normal paper printers, this extruder is also used to pour ink for printing. The movement of extruder in various dimensions creates the 3D print. For printing a 3d object, the extruder has to access X, Y and Z coordinates. For achieving this, many techniques are used according to the printer specification required for various applications.
If the 3D-Printer is a desktop printer, the Z axis movement of the extruder can be avoided and that function can be transferred to the print table. This will avoid complexity in 3D printing as well as time consumption.
Fig.2: Architecture
When the STL file is input to the printer, the microcontroller extracts each layer from it and also extracts each line segment from each layer. Then it gives controls to the movement of the extruder at required rate. The X-direction movement of extruder is made possible by the X-motor. When the X motor rotates , the shaft also rotates and the extruder moves in X direction.
The Y-direction movement of extruder is made possible by the Y-motor. When the Y motor rotates, the shaft also rotates and the extruder moves in Y direction. The X direction movement is made by the print table.
In the case of desktop printers, the printing ink is usually plastic wire that has been melted by the extruder at the time of printing. While printing, the plastic wire will melt and when it fall down to the printing table.
Consider printing larger objects like house using 3D printer. There will not be any X motor or Y motor in that case. An extruder which can pour concrete mix is fixed on the tip of a crane. The crane is programmed for the movement of extruder in X, Y and Z axis. The concept and structure of 3d printer changes according to the type, size, accuracy and material of the object that has to be printed.
Generalizing the facts, the extruder need to access all the 3 coordinates in space to print and object. The method used for that doesn’t matters much.
II. METHODOLOGY FOR PRINTING
There are some procedures for printing. First you must create a computer model for printing the object. For creating that, you can use Computer Aided Design Software like AutoCAD, 3DS Max etc. After the object file is created, the file need to be modified. The object file contains numerous amounts of curves. Curves cannot be printed by the printer directly. The curves have to be converted to STL (Stereo lithography) file format. The STL file format conversion removes all the curves and it is replaced with linear shapes. Then the file
needs to be sliced into layer by layer. The layer thickness is so chosen to meet the
Fig 3
resolution of the 3D printer we are using. If you are unable to draw objects in CAD software, there are many websites available which are hosted by the 3D printing companies to ease the creation of 3D object. The sliced file is processed and generates the special coordinates.
These coordinates can be processed by a controller to generate required signal to the motor for driving extruder. This layer by layer process generates a complete object.
2.1 Designing using CAD
Computer-aided design (CAD) is the use of computer systems to assist in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing. CAD output is often in the form of electronic files for print, machining, or other manufacturing operations.
CAD software for mechanical design uses either vector- based graphics to depict the objects of traditional drafting, or may also produce raster graphics showing the overall appearance of designed objects.
However, it involves more than just shapes. As in the manual drafting of technical and engineering drawings, the output of CAD must convey information, such as materials, processes, dimensions, and tolerances, according to application- specific conventions.
CAD may be used to design curves and figures in two- dimensional (2D) space; or curves, surfaces, and solids in three-dimensional (3D) space. CAD is an important industrial art extensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, prosthetics, and many more. CAD is also widely used to produce computer animation for special effects in movies, advertising and technical manuals, often called DCC digital content creation. The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques
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unheard of by engineers of the 1960s. Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics (both hardware and software), and discrete differential geometry. The design of geometric models for object shapes, in particular, is occasionally called computer-aided geometric design (CAGD). Unexpected capabilities of these associative relationships have led to a new form of prototyping called digital prototyping. In contrast to physical prototypes, which entail manufacturing time in the design? That said, CAD models can be generated by a computer after the physical prototype has been scanned using an industrial CT scanning machine.
Depending on the nature of the business, digital or physical prototypes can be initially chosen according to specific needs.
2.2 Conversion to STL file format
An STL file is a triangular representation of a 3D surface geometry. The surface is tessellated logically into a set of oriented triangles (facets). Each facet is described by the unit outward normal and three points listed in counter clockwise order representing the vertices of the triangle. While the aspect ratio and orientation of individual facets is governed by the surface curvature, the size of the facets is driven by the tolerance controlling the quality of the surface representation in terms of the distance of the facets from the surface. The choice of the tolerance is strongly dependent on the target application of the produced STL file. In industrial processing, where stereo lithography machines perform a computer controlled layer by layer laser curing of a photo-sensitive resin, the tolerance may be in order of 0.1 mm to make the produced 3D part precise with highly worked out details. However much larger values are typically used in pre-production STL prototypes, for example for visualization purposes.
The native STL format has to fulfil the following specifications:
(i) The normal and each vertex of every facet are specified by three coordinates each, so there is a total of 12 numbers stored for each facet.
(ii) Each facet is part of the boundary between the interior and the exterior of the object. The orientation of the facets (which way is “out” and which way is “in”) is specified redundantly in two ways which must be consistent. First, the direction of the normal is outward.
Second, the vertices are listed in counter clockwise order when looking at the object from the outside (right-hand rule).
(iii) Each triangle must share two vertices with each of its adjacent triangles. This is known as vertex-to-vertex rule.
(iv) The object represented must be located in the all-positive octant (all vertex coordinates must be positive).
However, for non-native STL applications, the STL format can be generalized. The normal, if not specified (three zeroes might be used instead), can be easily computed from the coordinates of the vertices using the right-hand rule. Moreover, the vertices can be located in any octant. And finally, the facet can even be on the interface between two objects (or two parts of the same object). This makes the generalized STL format suitable for modeling of 3D non- manifolds objects.
2.3 Choosing printing ink
Printing inks are chosen according to the need and kind of object that has to print. Different types of inks are available according to the size, type, resolution and function of the object.
Colloidal Ink: Three-dimensional periodic structures fabricated from colloidal “building blocks” may find widespread technological application as advanced ceramics, sensors, composites and tissue engineering scaffolds. These applications require both functional materials, such as those exhibiting Ferro electricity, high strength, or biocompatibility, and periodicity engineered at length scales (approximately several micrometers to millimetres) far exceeding colloidal dimensions.
Colloidal inks developed for robotic deposition of 3-D periodic structures. These inks are also called general purpose inks.
Fugitive Ink: These types of inks are used for creating soft devices. The type of ink is capable for self- organizing which results in self regenerative devices.
Nanoparticle Ink: The object that has to be printed sometimes need conductor for its function. For printing conductors, special types of inks called Nanoparticle inks are used.
Polyelectrolyte Ink: Polyelectrolyte complexes exhibit a rich phase behavior that depends on several factors, including the polyelectrolyte type and architecture, their individual molecular weight and molecular weight ratio, the polymer concentration and mixing ratio, the ionic strength and pH of the solution, and the mixing conditions. So such inks are used for creating sensors, transducers etc.
Sol-Gel Ink: In this chemical procedure, the 'sol' (or solution) gradually evolves towards the formation of a gel-like dysphasic system containing both a liquid phase and solid phase whose morphologies range from discrete particles to continuous polymer networks. In the case of the colloid, the volume fraction of particles (or particle density) may be so low that a significant amount of fluid may need to be removed initially.
III. APPLICATIONS
3D printing technology has been applied in various sectors. The applications of 3D printing potentially benefits a wide range of industries including defense, aerospace, automotive, biomedical and consumer products.
3.1 Hearing Aids
Hearing aids have been made using 3D printing technology.
3.2 Bio Printers
Organ printing or body part printing is being printed and some parts being used as implants of actual body parts.
Body parts such as titanium pelvic, plastic tracheal splint, titanium jaws to mention but a few have been printed.
3.3 Digital Dentistry
People are getting 3D printed teeth customized for the individual. Dental Implants are being made on a commercial level and making the whole process faster and more efficient. Before fake teeth used to be a one- size- fits - all depending with age. Now, people of the same age can have different sized teeth resulting in people getting discomfort with ill-fitting fake teeth.
Thus, customized implants have really brought a sigh of relief to the consumers as they are now able to receive teeth suited for them.
3.4 Prosthetics
A multitude of people are in need of surrogate body parts from people born without limbs to accident victims. The cost of getting surrogate body parts used to be extremely expensive but thanks to 3D printing; the cost has been significantly reduced.
Prosthetics has really done wonders to disabled people with the likes of Paralympics champion Oscar Pistorious being a world famous example.
3.5 Manufacturing
3D printing has introduced an era of rapid manufacturing. The prototyping phase is now able to be
skipped and go straight to the end product. Car and aero plane parts are being printed using 3D printing technology. The printing of parts is being done in a fast and efficient manner thus contributing immensely to the value chain.
Customized products are able to be manufactured as customers can make digital design file and send to the manufacturer for productions.
3.6 Academia
3D printing is now being integrated in the learning curriculum. With applications from printed molecule models to plastic gears. Students are now able to print their prototype models in 3D and it helps in the learning process of the students. Students are better able to understand concepts as it can be practically shown to them.
After the text edit has been completed, the paper is ready for the template. Duplicate the template file by using the Save As command, and use the naming convention
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prescribed by your conference for the name of your paper. In this newly created file, highlight all of the contents and import your prepared text file. You are now ready to style your paper; use the scroll down window on the left of the MS Word Formatting toolbar.
IV. CONCLUSION
The 3D print industry is set on a growth trajectory as evidenced by the growth forecasts [11]. The applications of 3D printing are increasing as more and more research is carried out. 3D printing will change the way people acquire products as evidenced by the Amazon proposed model. The field is definitely a game changer with lots of prospects to look out for.
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