how engineering is helping in bio medical sectors

1. Rapid prototyping
By: arpit kumar
M.P.O: 6th batch

2. Contents
● Introduction
● Workflow of R.P. process
● Types of rapid prototyping
● RP role in P and O field
● Example from journal research paper

3. Introduction
● A prototype is often used as a part of the product design process to allow
engineers and designers the ability to explore design alternatives,test theories
and confirm performance prior to starting production of new product.
● RP tech emloys various engineering eg. Computer control and software
techniques including laser,optical scanning, photosensitive polymers, material
extrusion and deposition, powder metallurgy etc to directly produce a physical
model layer by layer ( layer manufacturing) in accordance with the geometrical
data delivered from a 3D CAD model.

5. Rapid prototyping importance
● Can improve quality of requirements and specification provided to developers.
● Reduce time and cost
● Users are actively involved in the department
● Quick user feedback is available leading to better solutions.
● Error can be detected much earlier.
● Missing functionality can be identified easily.

6. Workflow of RP process
5 basic steps to follow:
1. Create a CAD model of the design.
2. Convert the CAD model to STL format.
3. Slice the STL file into thin cross-sectional layer.
4. Construct the model one layer atop another.
5. Clean and finish the model.

7. 1. CAD model creation
● First, the object to be built id modeled using a computer aided design
software package.
● Solid modelers, such as pro/engineers tends to represent 3D objects more
accurately than wire-frame modelers such as autoCAD and will therefore yield
better results.
● This process is identification for all of the RP nuild techniques.

8. 2. Conversion to STL format
● To establish consistency, the STL format has been adopted as the standard
of the rapid prototyping industry.
● The second step, is to convert the CAD file into STL format. This formats
represents a three dimensional surface as an assesmbly of planar triangles.
● STL FILE uses planar elements, they can not represent curved surface
exactly,increasing the n of triangles improves the approximation.

10. 3. Slice the STL file
● In the third step, a pre-processing program prepares the STL file to be built.
● The pre- processing software slices the STL model into a no. Of lauers from
0.01mm to 0.07mm thick, dependimg on the nuild technique.
● The program may also generate an auxillary structure to support the model
during the build. Supports are useful for delicate features such as overhangs,
internal cavities and thin- wallled sections

11. 4. Layer by layer construction
● The fourth step, is the actual construction part.
● RP machines build one layer at a time from polymers, paper or powdered
metal.
● Most machines are fairly autonomous, nedding little human intervention.

12. 5. Clean and finish
● The final step is post- processing. This involves removing the prototype from
the machine and detaching any supports.
● Some photosensitive material needs to be fully cured before use.
● Prototype may also require minor cleaning and surface treatment.
● Sanding,sealing,and or painting the model will improve its appearance and
durability.

14. Types of Rapid protoyping tech
1. SLA- stereolithography
2. SLS- selective laser sintering
3. LOM- laminated object manufacturing
4. FDM- fused deposition modelling
5. 3DP- three dimensional printing

15. 1. SLA
● SLA patented in 1986, started the rapid prototyping revolution. The technique
builds 3 dimensional model from liquid photosensitive polymers that solidify
when exposed to ultraviolet light.

18. 2. SLS
● Selective laser sintering process that builds model from a wide variety of
mayerial using an additive fabrication method.
● The build media for SLS comes in powder form, which is fused together by a
poweful carbom dioxide laser to form the final product.

19. Contd.
● The build media for SLS comes in powder form, which is fused together by a
powerful carbon di oxide laser to form the final product.
● SLS currently has 10 different build materials that can be used within the
same machine for a wide variety of applications.
● The SLS process begins like most other RP process with the standard .STL
CAD file format, which is exported now by most 3D CAD packages.

21. Contd.
Materials that can be used:
1. Plastic powders
2. Metal powders( direct metal laser sintering)
3. Ceramic powders
4. Glass powders

22. 3. Fused deposition modeling ( FDM)
● FDM is a solid based RP method that extrudes material , layer by layer to
build a model.
● A thread of plastic is fed into an extrusin head, where it is heated into a semi-
liquid state and extruded through a very small hole onto the previous layer of
material.
● Support material is also laid down in a similar manner.

24. Contd.
Advantages:
● Easy fabrication
● Minimal wastage
● Ease of removal
● Easy handling
Application range:
● Designing
● Engineering analysis and planning
● Tooling and manufacturing

25. 4. Three dimensional printing(3DP)
● The process of creating an object using a machine that puts down material
layer by layer in 3 dimensions until the desired object is formed.
● A 3D printer extrudes melted plastic filament or other material, building
objects based on specifications that come from moedling software or from the
scan of an existing object.

29. RP role in p and o field
● Reduces professional dependancy
● Producing more consistent socket fit.
● Provides more flexibility in rectification process.
● Allowing future replication of replica socket
● Eliminating plaster mould work process

30. Example from journal reserach
Fabrication of TRANSTIBIAL socket using RAPID
PROTOTYPING:
1. scan the stump to obtain digitized data: portable handheld
scanner scans the residual stump and digital data is obtained.
1. Construct the CAD stump model: construction of a CAD
model using the scanned points. This step screens abnormal
points and utlizes an in-house interface system to build a mesh
model.
1. Modifying the CAD stump model: pressure releif and sensitive
area are modified according to prosthetist wishes.
1. Create socket 3D model: this step generates a CAD model so
that the RP machine can fabricate a socket.
● The geometric shape of the socket should be larger than the
stump.
● Using CATIA system , extending the length at the end of the
modified stump model to keet the amoutee requirement.
● The method then acquires a socket model with 2 mm thickness
and transfer its data in STL format to an RP madhine.

31. Contd.
● Fabricate preliminary RP socket: This study chooses an FDM machine, and
designates polycarbonate (a widely adopted RP material) to form a
preliminary RP socket.
● Coat the UPR layer to reinforce RP socket: laimination is done over the RP
socket.

32. Thank you.