Technical Paper Presentation
On
3D Printing Technlogy and Engineering Applications

 Guided by
 Prof.S.P.Alone 

         Presented by                
Sushma Rahangdale
Dipali Bhure
	Sonam Ramteke

For the Degree of Bachelor of Mechanical Engineering
DEPARTMENT OF MECHANICAL ENGINEERING
MADHUKARRAO PANDAV COLLEGE OF ENGINEERING
BHILEWADA,BHANDARA

     3D Printing Technlogy and Engineering Applications

Abstract
A 3D printer uses a virtual, mathematical model to construct a physical artifact. For example, a designer in the process of creating a new laptop can use a software package to create a three-dimensional model of her creation, that can be manipulated and viewed on the computer screen. The 3D printer can take the symbolic representation of this new object and use it to build a full-size, physical model that can be held and manipulated, helping the designer to better understand the strengths and limitations of her design. An architect can turn the plans for a building into a three-dimensional model and then “print” a scale model to help him understand and communicate his design. An archaeologist can print duplicates of an important, but fragile, tool so that her students can hold it in their hands and better understand how it might have been used by an ancient civilization. A biochemist can print accurate models of DNA molecules, enlarged by many orders of magnitude, to help students and researchers better understand nature by engaging their hands as well as their eyes in comprehending the geometry of nature. And a student of the arts can create a unique object that would be difficult or impossible to build by hand.
We will not here consider other types of computer-controlled manufacturing, such subtractive machines, which work by cutting away from a larger piece of material in order to build a part.Additive rapid prototyping machines were first introduced twenty years ago, when 3D Systems introduced the Stereolithography, or SLA machine. While these machines were remarkable for their ability to create complex parts, they were (and continue to be) large, expense, and difficult to operate. As such, they are of limited interest to most academic institutions except for a few well-funded laboratories. However in the latenineties lower cost machines using technologies such as fused-deposition modeling 
(FDM) and powder binding (defined below) began to be available in the $30,000 to $50,000 range. These machines, which can be used without special environmental controls and with a modest amount of training, are the first 3D printers by our definition.
In the evolution of rapid prototyping equipment, we have seen a history somewhat like that of the mainframe computer (SLA) and the mini-computer (early FDM and powder binding) systems. However, we are on the verge of the introduction of new systems that will cost less than $10,000, require very little training, and are capable of being operated in a typical faculty office or computer lab or home. At least one vendor has the ambition of producing 3D printers for less than $1000 in five years. It is the thesis of this paper that as these printers achieve lower price points and accessibility, they will spring up across campuses and be used for applications yet to be imagined. Our purpose is to disseminate a basic understanding of a technology that is likely to grow dramatically in popularity within the next few years.

Introduction :
3D Printing: process and equipment
To use a 3D printer, you have to have something to print. In most cases, users create their models using a commercial CAD tool such as Solidworks or Rhinoceros. This complex software can be quite expensive, but as it has come into wide use academic licenses are generally available for several hundred dollars a seat. Occasionally lower-cost software such as SketchUp, available in free and in “pro” versions can be used, but with some limitations since SketchUp was not designed to create manufacturable objects. As lower cost printers become available, the software market is likely to broaden and new, simpler programs may become available, analogous to the drop in cost and complexity of desktop publishing software in the 1990’s. Commercial 3D CAD software also places demands on computer processing power and memory, although the vast majority of the newer multi-core systems will be more than adequate for most modelers.
The current generation of 3D printers typically require the output from the CAD program to be stored in a format called STL, which defines a shape by a list of triangle vertices. This step is largely invisible to the user, although the output may need to go through an automated “clean up” step to reduce anomalies that might be invisible on a screen but could impact the printing process. Then the cleaned up STL file is used to drive the 3D printer.
The Working Principle :
The term additive manufacturing refers to technologies that create objects through a sequential layering process. Objects that are manufactured additively can be used anywhere throughout the product life cycle, from pre-production (i.e. rapid prototyping) to full-scale production (i.e. rapid manufacturing), in addition to tooling applications and post-production customization.
In manufacturing, and machining in particular, subtractive methods are typically coined as traditional methods. The very term subtractive manufacturing is a retronym developed in recent years to distinguish it from newer additive manufacturing techniques. Although fabrication has included methods that are essentially "additive" for centuries (such as joining plates, sheets, forgings, and rolled work via riveting, screwing, forge welding, or newer kinds of welding), it did not include the information technology component of model-based definition. Machining (generating exact shapes with high precision) has typically been subtractive, from filing and turning to milling and grinding.
Modeling
Additive manufacturing takes virtual blueprints from computer aided design (CAD) or animation modeling software and "slices" them into digital cross-sections for the machine to successively use as a guideline for printing. Depending on the machine used, material or a binding material is deposited on the build bed or platform until material/binder layering is complete and the final 3D model has been "printed." It is a WYSIWYG process where the virtual model and the physical model are almost identical. A standard data interface between CAD software and the machines is the STL file format. An STL file approximates the shape of a part or assembly using triangular facets. Smaller facets produce a higher quality surface. PLY is a scanner generated input file format, and VRML (or WRL) files are often used as input for 3D printing technologies that are able to print in full colors.
Printing
the fundamental purpose of a 3D printer is to quickly transform an idea into a physical object. that idea is usually first embodied in a 3D computer model created in 3D cAD software like solidworks®, Autodesk® inventor® or Pro/engineer®. 

All of these software tools export 3D models as files in standard formats for 3D printing, including .stl, .wrl (vrMl), .PlY, .3Ds and .ZPr. the exported file is a mesh, or series of  triangles oriented in space, that enclose a 3D volume. this mesh must be “water tight” so that the model is a solid, not just surfaces that may not have any thickness (see figure 1.1 on page 5). in other words, the design at this point must be ready to exist in the real world, not just on a computer. with the file now in a printable format, you launch ZPrint™  software on your Pc. using ZPrint, you can scale up or scale  down the file you wish to print, orient the part in the build chamber, and direct the 3D printer to print multiple versions  of the part in the same build (with or without variations). Then ZPrint slices the 3D model file into hundreds of digital  cross-sections, or layers. each 0.004 inch (0.1 mm ) slice  corresponds to a layer of the model to be fabricated in the printer.
w hen ready to start the print job, you click “3D Print.” this sends the digital layer files to the ZPrinter, and the model begins printing immediately. 
The Printer prints each layer, one atop another, as the physical part is constructed within the build chamber of the machine. we’ll detail how the ZPrinter accomplishes this task next. once the Printer completes the final layer, a short drying cycle runs. then the physical object can be removed.

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