2. • RP is a term that emphasis on creating something quickly and that the
output is a prototype or basis model from which further models and
eventually the final product will be derived.
• It is previously used to describe the development process in
piecewise fashion to clients.
• It is necessary to used RP because convention fabrication requires
detaled planning which consumes more time.
3. • Initially Rp is just for prototyping, but later due to its advantages its is
evolved into AM due to technologies advancements.
• Since the fabricated product is more linked to final one, it is not
correct to describe it still as prototype. So, it is renamed as AM or 3d
Printing.
• Do to recents advancements in technology, RP doesn’t fully described
the actual process, so it is renamed as AM or 3D printing.
• AM technology significantly simplifies the process of producing
complex 3d objects directly from cad data.
4. • AM only needs basic dimensional details and understanding of AM
machine working and material available.
In AM, parts are fabricated by adding material in layers, where
each layer is a cross-section the part derived from the 3D CAD
model.
5. The thickness of the layer depends on the requirement and
fabricated AM machine. Thinner the layers, closer to the
original cad model.
• All the commericialized AM machines to date use this approach. But
only difference how the layers is created, bonded and materials can
be used.
• These differences determine factors like accuracy, properties,
fabrication time, postprocessing required, AM size, cost of machine
and process.
6. Uses
• Initially AM was used specifically to create visualization models.
• Since models are more helpful than drawings or renderings.
7. Development of AM
• Computer
• First computer build in 1940s Zuse Z3, ENIAC, EDSAC
• Thermionic value, transistor and microchip helped to become faster
smaller and cheaper computer with greater functionality.
• They have the ability to perform tasks in real time.
• IN earlier days computer took many hours and days to complete
computational tasks.
• Gaming industry pioneered many developments in graphics
technology with aim to display more detailed and realistic images.
8. Development of AM
• Computer
• Processing power, graphics capability with gui, machine control
required to processing the positioning with computing power,
computation is necessary for processing thiese.
9. Development of AM
• CAD
• Early CAD systems are limited by display technology. Computer also
helped CAD systems.
• Only a branch of a much larger set of CAD systems is suitable to
produce output for layer based AM.
• CAD improvementsL
• Realism: lightning and shading effects, visualization
• GUIs
• Engineering content:
• Speed, accurate, complexity, accessability.
10. Development of AM
• CAM
• It represents a channel ro convering the virtual models developed in CAD
into the physical products that we use in our everyday lives.
• CAM systesm produce the code for NC machinery, essentially combining
coordinate data with commands to select and actuate the cutting tools.
• NC machines are known for precise, automated functionality and features
complexity increased. But NC machines are limited by performing
operations in stages.
• And also, they are 2.D manufacutirng. Means workpiece has to be
orientated in a particular direction and not accessible at single stage.
11. Development of AM
• CAM
• NC machining, only requires surface modelling.
• AM was first automated CAD which required 3D solid modelling CAD.
12. Process Chain
• Step-1: Conceptualization and CAD
• A detailed 3d Cad model has to made with desired requirements using CAD
softwares. Although visually the model is fine, but in reality the model is not
fully closed some errors like missing faces, gaps, incorrect edges, duplicate
edges etc. These has to taken care.
• Step-2: STL convert (standard tessellation language) or standard
triangle language
• Tesselation means breaking the surface of the geometry into series of
triangles. First developed during SLA. Two encondings are ascii and binary
• 3. Slicing in a 3d printing software directly connected to the 3d printer
or am machine
• It chops the model into horizontal layers based on the user settings. We
choose and also calculates the material requirements and time taken to print.
13. Process Chain
• Slicing software generates g-code based on the stl files. This g-codes is usually
used to generate tool paths in cnc machines. Similarly here also, it guide the
tool path. Tool depends on the type of am technology which can be before
later.
• Machine setup: machine has to prepared for 3d printing and material
loading and cleaned
15. AM classification
• Liquid polymer systems
• The first commercial system was the 3d systems stereolithography
process based on this.
• A laser is used to solidy the polymer.
16. AM classification
• Discrete particle systems
• Material powders with uniform particle size and shape and narrow
size distribution.
• Use a laser, thermal energy is produced in a controlled manner to
melt the powder. Then particles are bonded due to melting. Likewise
each layer is produced and layer by layer part is fabricated.
17. AM classification
• Molten material systems
• Material is melted in melting chamber, and it is delivered through a
extrusion system in a controlled manner.
18. AM classification
• Solid sheet systems
• Laminated Object manufacturing system
• here, profile layers of the part is cut out on the material sheet roll,
and the layers are bonded together using a heat –activated resin
coated on the layers.
19. Vat photopolymerization
• It make use of liquid, radiation-curable resins, or photopolymers, as
their primary materials.
• Photopolymers are the materials which are sensible to UV range of
wavelengths, (some to visible also). Upon exposing to those
wavelengths, they undergo a chemical reaction and become a solid.
This is knows as photopolymerization.
• Initial uses of photopolymers are coatings, dentistry.
• Stereolithography is the first vat photopolymerization process
20. Vat photopolymerization
• In mid 1980s, Charles Chuck Hall experimented on UV-curable
photopolymers and fabricated a part layer by layer. This is beginning
of stereolithography.
• Radiation variations are used including gamma rays, X-rays, electron
beams, UV.
21. • The first powder bed fusion process commercialized is Selective laser
sintering SLS.
• It uses a bed of small particles ( made of plastic, metal, ceramic, or
glass)
• Energy source beams are traced (laser) layer wise on the powder bed
surface fusing the particles.
• The platform descends by one layer and more material is added.
• All other PBF processes modify this basic approach for better
accuracy and for different materials.
Power Bed Fusion Processes
22. Power Bed Fusion Processes
• Characteristics:
• Thermal energy source: generally lasers
• Mechanisms for adding and smoothing powder layers
• No supported structures are required.
23. Extrusion-based systems
• Can be visualized as similar to cake icing
• Material contained in a reservoir is forced out through a nozzle by
applying pressure and deposited in a layer wise fashion.
24. Extrusion based systems
• The pressure applied, travel speed of nozzle determines the diameter
of roads.
• Basic principles
• Loading and liquification of material ( in some machines liquification is
skipped)
• Pressure application and extursion
• Movement of nozzle in a controlled manner in defined path
• Bonding and inclusion of support
• Temperature controllers
