The presentation covers all the methods of Rapid protoyping and various aspects related to it. The Topics covered in the presentation are 1) Droplet Deposition Manufacturing 2) Laminated Object Manufacturing 3) Fused Deposition Modeling 4) Selective Laser Manufacturing 5) Sterolithography

1. Unit 3
Rapid Prototyping

2. Definition
Rapid Prototyping (RP) can be defined as a group of techniques used to quickly fabricate a scale model of
a part or assembly using three-dimensional computer aided design (CAD) data.
It is made from two words “Rapid” means fast and prototyping means model,sample or concept
In this process the model can be generated within few minutes to hours as compared to the conventional
process which requires the months to weeks to complete the project

4. Need of Rapid Prototyping
(ADVANTAGES)
1. Reduction in time
2. Manufacturing of complex products
3. Development of new products
4. Competitive advantage
5. Testing for manufacturing and design
6. Testing for consumer satisfaction
7. Cost saving
8. Easy patent
9. Help in manufacturing
10. Marketing and advertising

5. lIMITATION
1. Skilled labour required
2. Expensive in some cases
3. Strength may be compromised
4. Material selection is limited

6. Applications
1. Design
2. Engineering analysis
3. Planning
4. Tooling
5. Manufacturing

7. Cycle of Rapid prototyping

8. Fundamentals of Rapid Prototyping
1) Material Removal Rapid Prototyping
2) Material Addition Rapid Prototyping
A) Use of Liquid Monomers
B) Use of powders
C)Use of Solid Sheets

9. Common method used for Rapid
Prototyping
1) CAD Model Creation
2) Conversion to STL Format ( Stereolithographic Format)

10. 3) Pre Processing of STL format ( Minimizing the amount of time, selection of best path,
number of layers, generation of auxiliary structure to support the main structure, orientation
and coordinate
4) Layer by Layer construction ( Powder, sheet or liquid monomers )
5) Cleaning and finishing

11. Classification of Rapid prototyping
methods
1) Liquid based Rapid Prototyping- Stereolithography, solid Ground curing, Droplet
Deposition based
2) Solid based Rapid Prototyping- Laminated Object, Fused Deposition
3) Powder Based rapid prototyping - Selective Laser sintering, three dimensional printing

12. Stereolithography
Stereolithography (SLA) is an additive manufacturing process that builds solid prototypes, patterns
and products from CAD drawings.
SLA enables the construction of solid plastic prototypes that are weaved from a CAD-powered laser
beam gun.
Layer by layer construction of part is done to ensure high accuracy

13. Step 1: Laser beam is directed towards the
photosensitive material. This laser beam helps
to harden the photosensitive material
Step 2: As the new layer harden the second
layer is formed on top of it according to the
STl file
Step 3: As each new layer is hardeded a wipe
blade is passed to ensure proper surface
finish and level

16. Advantages :
1. High and excellent dimensional accuracy
2. Better Surface Finish
3. Unattended System
Inexpensive Method
Disadvantages :
1. Components are subjected to twists
2. Environmentally hazardous
3. Requires support structure
4. Resins are expensive
Applications: Making patterns, moulds and dies, electronics, aerospace and decorative
products

17. Solid ground Curing
Solid ground curing works by curing a photosensitive polymer layer by layer to create an solid
model
In this process the resin in each thin layer is covered with a photomask which is then exposed
to UV light and is cured in few seconds.
The unexposed liquid is then removed and the voids are filled with molten wax to support the
next layer
https://www.youtube.com/watch?v=m1aQvaBNaEY

19. Advantages:
1. High surface quality
2. High accuracy
3. High speed
4. Sharp corners and other complex shapes can be easefully made
Disadvantages:
1. It requires post processing of the finished job
2. Careful handling is required
3. High cost of materials

20. Droplet Deposition Manufacturing
Droplet deposition manufacturing system operates by melting the starting material and
shooting small droplets on previously formed layers
The wax is used as an working material in this process
Working: The ejector heads operates using an piezoelectric oscillator that shoots droplets of
wax at a rate of 10000-15000 drops per second. The droplets are of uniform size which
flatten to about 0.05 mm after solidification. The solidification takes place due to heat and
impact of droplets.

21. Source: https://www.sciencedirect.com/science/article/pii/S0890695514001412

22. Laminated Object Manufacturing
Laminated object manufacturing (LOM) is a rapid prototyping system In it, layers of adhesive-coated paper,
plastic, or metal laminates are successively glued together and cut to shape with a knife or laser cutter
The process is performed as follows:
1. Sheet is adhered to a substrate with a heated roller.
2. Laser traces desired dimensions of prototype.
3. Laser cross hatches non-part area to facilitate waste removal.
4. Platform with completed layer moves down out of the way.
5. Fresh sheet of material is rolled into position.
6. Platform downs into new position to receive next layer.
7. The process is repeated until full model or prototype prepared.
https://www.youtube.com/watch?v=m0b3WIS2nqw

24. Advantages:
1. Simple and cheap Method
2. Material type can be changed easily
3. Materials are not hazardous
4. Method does not require any support
Disadvantages:
1. Surface finish is not good
2. Need careful handling
3. Cannot produce components with complex walls

25. Fused Deposition Modeling
Fused deposition modeling (FDM) is an additive manufacturing (AM) process in which a
physical object is created directly from a computer-aided design (CAD) model using
layer-by-layer deposition of a feedstock plastic filament material extruded through a
nozzle

27. Selective Laser Sintering
Selective laser sintering (SLS) is an additive manufacturing (AM) technique that uses a laser as the power source
to sinter powdered material (typically nylon or polyamide), aiming the laser automatically at points in space defined
by a 3D model, binding the material together to create a solid structure.
In contrast with some other additive manufacturing processes, such as stereolithography (SLA) and fused
deposition modeling (FDM), which most often require special support structures to fabricate overhanging designs,
SLS does not need a separate feeder for support material because the part being constructed is surrounded by
unsintered powder at all times, this allows for the construction of previously impossible geometries
An additive manufacturing layer technology, SLS involves the use of a high power laser (for example, a carbon
dioxide laser) to fuse small particles of plastic, metal, ceramic, or glass powders into a mass that has a desired
three-dimensional shape. The laser selectively fuses powdered material by scanning cross-sections generated from
a 3-D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed. After
each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied
on top, and the process is repeated until the part is completed

29. 3D Printing
The 3D printing method builds the part in layer by layer fashion using an inkjet printer to
eject an adhesive bonding material.
The 3D printers use binders to deposit the material where an adhesive bond is to be created
When the process is completed the part is heated to develop required strength in the
material
https://www.youtube.com/watch?v=Vx0Z6LplaMU