3d Printing

Name : Siddhant H Pathak Roll no: 21Sem : 2Department of Materials Science

• Last winter, Jan 2013 in Michigan USA “kaiba geon--frido” Age-3 months was struggling between life and death, it was born with a very deadly defectcalled “tracheobronchomalacia” • That is the Pulmonary artery(of the heart) was

intertwined over his bronchi(left wind pipe of his lung)hence air was unable to reach his left side of the lung and he had to be kept on ventilator• In such a case it was impossible for little kaiba

to lead a normal life because his left wind pipewas completely crushed by pulmonary arterythe defect was in the basic structure of his body• No kind of repairing would be able to cure

kaiba because the defect was irrepairablethe only way out would be to replace the verypart of little kaiba’s body or he would die after allno body having such defect have lived till date.• At this hour of need the chief surgeon of Michigan

hospital Glenn Green called for 3d printerand its expert Scot Holister, a biomedical engineerat Michigan University

0• After a tedious and gruesome analysis

of size, geometry, structure and workingof the wind pipe it was decided that this windpipe would be created artificiallyby the 3d printer to exactly suit the requirement of little kaiba by a specialtype of thermoplastic called“Polycaprolactone”

• Now Polycaprolactone is an extremelyinert and biocompatible material,this was 3dprinted to give a form of hollow structure like that shown

• This designed piece was boundover the defected part of littlekaiba

• The baby who could not have lived more than a few minutes out of the ICU was given a gift of living an absolutely normal life. All because of a desktop PC sized gadget …….. 3-d printer

Index•What is 3d printing•Digital Printing•3d printing processes•Applications•References

What is 3d printing ?• 3d printing is a kind of manufacturing process

in which you can make a three dimensional solid object of virtually any shape and typefrom its digital model• This digital model can be created by CAD(a

digital software) or by 3d scanningby•

3d printing is different from traditional manufacturing process as the tradional method used for the purpose of manufacturing is a subtractive process, i.e procedures like filing, cutting, grinding, milling etc are used

• to remove the unwanted material in order to give the desired shape for the desired quality and working of a product• 3d printing is an exactly opposite process termed as additive manufacturing in

which the objects are created through sequential layering i.e. the material of which the substance is to be made is printed layer after layer in order to get the final product.• Hence the biggest benefit when is made on

large scale through 3d printing is that “There is completely 0 wastage of material”• Hence 3d printer is a type of industrial

robot that is capable of carrying outadditive manufacturing process under computer control.

Digital Printing• To perform a print, the machine reads the design from 3D printable file (STL file)

STL(STandard Lithiography aka Standard Tesselation Language) it is a widely used file format supported by many software packages widely used in rapid prototyping and CAM• The STL format are specified in both ASCII and binary representations. However

binary files are more common, since they are more compact.• An STL file describes the cross sectional surface of the object by the unit normal

and vertices of the triangles using a three-dimensional Cartesian coordinate system.• The layers cross sectional layers of the material which corresponds to the digital

design are joined or automatically fused together to obtain the final shape by the command written in STL format

• The actual printing is carried out bythe mechanism of the printerwhere two nozzles as shown onthe right oozes out the materialdrop by drop, materials used arenormally a thermoplastic likepolystyrene, Polylactic acid,HDPE etc i.e the materials with lowmelting point and good thermal and structural stability.• Here the rod on which the nozzle is

bound with moves in the Z-direction while the platform on which the desired object is being formed can move in the X-Y plane• The movement of these planes would be synchronised such that they will

together move to exactly form the desired object.

• Like normal printers even 3d printers have resolution that describes the thickness of the material and is measured in dots per inch(dpi) or mirometers• Typical layer thickness is around 100 µm (250 DPI), although some machines such

as the Objet Connex series and 3D Systems can print layers as thin as 16 µm (1,600 DPI) with their X-Y resolution comparable to that of laser printers where the particles (3D dots) are around 50 to 100 µm (510 to 250 DPI) in diameter.• Construction of a model with contemporary methods can take anywhere from

several hours to several days, while this additive system can typically reduce this time to a few hours• Traditional techniques like injection molding can be less expensive for

manufacturing polymer products in high quantities, but additive manufacturing can be faster, more flexible and also less expensive especially when producing relatively small quantities of parts not mentioning that you also have a size advantage over traditional machinery as 3d printer is almost the size of a desktopcomputer.

3d printing processes• A large number of additive processes are available. They differ in the way layers

are deposited to create parts and in the materials that can be used. • Some methods melt or soften material to produce the layers, e.g. selective laser

melting (SLM) or direct metal laser sintering (DMLS) for which Titanium alloys, Cobalt Chrome alloys, Stainless Steel and Aluminiums are used.• Selective laser sintering (SLS), which uses thermoplastics ceramic powder and

metal powder, Fused deposition modeling (FDM) which uses thermoplastics eutectic metals, rubber metal clay, plasticine and even edible materials • Some methods cure liquid materials using different sophisticated technologies,

e.g. stereolithography (SLA). Which includes laminated object manufacturing (LOM) in which thin layers are cut to shape and joined together (e.g. paper, polymer film, metalcoils). • Each method has its own advantages and drawbacks

Fused Deposition Modeling• In fused deposition modeling the model or part is

produced by extruding small beads of material which harden immediately to form layers. • A thermoplastic filament or metal wire that is

wound on a coil is unreeled to supply material to an extrusion nozzle head. The nozzle head heats the material and turns the flow on and off.• Typically stepper motors or servo motors are

employed to move the extrusion head and adjust the flow and the head can be moved in both horizontal and vertical directions.• Various polymers are used, including acrylonitrile butadiene styrene (ABS),

polycarbonate (PC), polylactic acid (PLA), high density polyethylene (HDPE) and polyphenylsulfone (PPSU). In general the polymer is in the form of a filament, fabricated from virgin resins.

Granular Materials Binding• Another 3D printing approach is the selective

fusing of materials in a granular bed. The technique fuses parts of the layer, 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 being produced, which reduces the need for temporary auxiliary supports for the piece. A laser is typically used to sinter the media into a solid. Examples include selective laser sintering (SLS) which uses both metals and polymers and direct metal laser sintering (DMLS) which uses only metals.• Selective Laser Melting (SLM) does not use sintering for the fusion of powder granules but

completely melts the powder using a high-energy laser to create fully dense materials in a layerwise method with similar mechanical properties to conventional manufactured metals.

Laminated object manufacturing• In some printers, paper can be used as the

build material, resulting in a lower cost to print. During the 1990s some companies marketed printers that cut cross sections out of special adhesive coated paper using a carbon dioxide laser, and then laminated them together.• In 2005, Mcor Technologies Ltd developed a

different process using ordinary sheets of office paper, a Tungsten carbide blade to cut the shape, and selective deposition of adhesive and pressure to bond the prototype.• There are also a number of companies selling

printers that print laminated objects using thin plastic and metal sheets.

Photo Polymerisation• In photopolymerisation, a vat of liquid

polymer is exposed to light from a DLP projector under safelight conditions. The exposed liquid polymer hardens. • The build plate then moves down in small

increments and the liquid polymer is again exposed to light. The process repeats until the model has been built. The liquid polymer is then drained from the vat, leaving the solid model.• In some inkjet type system like object

polyjet Photopolymer material is sprayedin ultrathin layers(16-30 microns), each layer is cured with UV light which produces fully cured objects that can be handled and used immediately.

Applications• Fire Arms

Cody Wilson in the picture below, is a student at texas, America he has made asemi-Automatic rifle athome 3d printed …of course !!!

• US department of homeland security has disclosed of plans todesign a working plastic gun that could be downloaded and reproduced by anybody with a 3D printer.

This printer is a brainchild of Dr. Behrokh Khoshnevis from the University of Southern California.Here we can see two tracks guiding the Contour Crafting device along as it extrudes cement along a programmed floor plan.

It is hoped that the device will be used to provide low-cost shelter for the estimated 1 billion people living in substandard housing around the globe. It could also be used to quickly restore housing to those lost in natural disasters, such as those displaced by the hurricane in the Philippines late last year.

Other applications• Clothing

making clothes of desired designs and materials, not at all necessary to bulk produce it.• Archeology and palaeontology

reconstructing fossils and replicating ancient and priceless artifacts• Space Exploration

reduction in pay load• Forensics

reconstructing bones and body parts in forensic pathology, and reconstructing heavily damaged evidence acquired from crime scene investigations• Printing 3d printers

References:

• Safari Magazine, February 2014 ,Issue no. 237Article: Super Sawaal• Wikipedia• Facebook/I love science.com• Google images