Rapid Prototyping

1
Rapid Prototyping
Mechanical Engineering Department MENG 439 Dr. L.
K. Gaafar

• By,
• Khaled Nounou
• Medhat Nabet
• Youssef Shaheen

2
Outline

• Introduction
• Rapid Prototyping Technique
• Rapid Prototyping Processes
• SLS --- Selective Laser Sintering
• SLA --- StereoLithography
• LOM --- Laminated Object Manufacturing
• FDM --- Fused Deposition modeling
• Economic Evaluation
• Safety considerations
• Questions

3
Introduction

• Rapid Prototyping (RP) techniques are methods
  that allow designers to produce physical
  prototypes quickly.
• It consists of various manufacturing processes by
  which a solid physical model of part is made
  directly from 3D CAD model data without any
  special tooling.
• The first commercial rapid proto typing process
  was brought on the market in 1987.
• Nowadays, more than 30 different processes (not
  all commercialized) with high accuracy and a
  large choice of materials exist.
• These processes are classified in different ways
  by materials used, by energy used, by lighting of
  photopolymers, or by typical application range.

4
Rapid Prototyping Technique

• In the Rapid Prototyping process the 3D CAD data
  is sliced into thin cross sectional planes by a
  computer.
• The cross sections are sent from the computer to
  the rapid prototyping machine which build the
  part layer by layer.
• The first layer geometry is defined by the shape
  of the first cross sectional plane generated by
  the computer.
• It is bonded to a starting base and additional
  layers are bonded on the top of the first shaped
  according to their respective cross sectional
  planes.
• This process is repeated until the prototype is
  complete.

5
Rapid Prototyping Technique

• Process Flow

3D Solid modeling
Data preparation
Part Building
Pass
Reject
Redesign
6
Rapid Prototyping Technique
7
Rapid Prototyping Processes

• SLS --- Selective Laser Sintering
• SLA --- Stereolithography
• LOM --- Laminated Object Manufacturing
• FDM --- Fused Deposition Modeling
• Others

8
Rapid prototyping Processes
SLS SLA LOM FDM

• SLS

9
Rapid prototyping Processes

• Application Range
• Visual Representation models
• Functional and tough prototypes
• cast metal parts

10
Rapid prototyping Processes

• Advantages
• Flexibility of materials used
• PVC, Nylon, Sand for building sand casting cores,
  metal and investment casting wax.
• No need to create a structure to support the part
• Its parts do not require any post curing except
  when ceramic is used.
• Disadvantages
• During solidification, additional powder may be
  hardened at the border line.
• The roughness is most visible when parts contain
  sloping (stepped) surfaces.

11
Rapid prototyping Processes
SLS SLA LOM FDM

• SLA

12
Rapid prototyping Processes

• Application Range
• Parts used for functional tests
• Manufacturing of medical models
• Form fit functions for assembly tests

13
Rapid prototyping Processes

• Advantages
• Possibility of manufacturing parts which are
  impossible to be produced conventionally in a
  single process
• Can be fully atomized and no supervision is
  required.
• High Resolution
• No geometric limitations
• Disadvantages
• Necessity to have a support structure
• Require labor for post processing and cleaning

14
Rapid prototyping Processes
SLS SLA LOM FDM

• LOM (Laminated Object Manufacturing)

15
Rapid prototyping Processes

• Application Range
• Visual Representation models
• Large Bulky models as sand casting patterns

16
Rapid prototyping Processes

• Advantages
• Variety of organic and inorganic materials can be
  used
• Paper, plastic, ceramic, composite
• Process is faster than other processes
• No internal stress and undesirable deformations
• LOM can deal with discontinuities, where objects
  are not closed completely
• Disadvantages
• The stability of the object is bonded by the
  strength of the glued layers.
• Parts with thin walls in the z direction can not
  be made using LOM
• Hollow parts can not be built using LOM

17
Rapid prototyping Processes
SLS SLA LOM FDM

• FDM (Fused Deposition Modeling)

18
Rapid prototyping Processes

• FDM

19
Rapid prototyping Processes

• Application Range
• Conceptual modeling
• Fit, form applications and models for further
  manufacturing procedures
• Investment casting and injection molding

20
Rapid prototyping Processes

• Advantages
• Quick and cheap generation of models
• There is no worry of exposure to toxic chemicals,
  lasers or a liquid chemical bath.
• Disadvantages
• Restricted accuracy due to the shape of material
  used, wire is 1.27 mm diameter.

21
Rapid prototyping Processes

• Other Processes
• Ballistic Particle Manufacturing (BPM)
• This process uses a 3D solid model data to direct
  streams of material at a target.
• 3D Printing
• It creates parts by layered printing process. The
  layers is produced by adding a layer of powder to
  the top of a piston and cylinder containing a
  powder bed and the part is being fabricated.
• Model Maker
• It uses ink jet printer technology with 2 heads.
  One deposits building material, and the other
  deposits supporting wax.

22
Rapid Prototyping Products
23
Economic Evaluation

• Requires special labor, methods and equipments.
• High equipment cost approximately 200 000.
• Fast production of physical prototypes with no
  lead time required.
• Early introduction of products to markets.
• Encourages and Facilitates product development.
• High operational expenses (laser replacement 10
  000), (maintenance 15 000 per year).
• More cost effective for sophisticated and complex
  models.
• The spread of this technology can dramatically
  decrease the equipment cost.

24
Safety Considerations

• The door of the rapid prototyping machine should
  be locked.
• Special ventilation for the processes that emit
  toxic gasses.
• Wearing safety coat and gloves when using
  processes that use toxic chemicals.
• Avoid interference with laser beams, UV rays and
  hot waxed parts.

25
References

• Kochan D., Solid Freeform Manufacturing 1993.
• Zhang G., Richardson M., Economic Evaluation of
  Rapid Prototyping in the Development of new
  Products.
• http//ecoleing.uqtr.uquebec.ca/geniedoc/gmm/produ
  ctique/rp_gener.htm
• http//www.biba.uni-bremen.de/groups/rp/rp_intro.h
  tml
• http//www.cadcamnet.com/Default.htmRPReport