1. Dr. Lotfi K. Gaafar 2002 Rapid Prototyping BY G.BHARATH REDDY

2. Dr. Lotfi K. Gaafar 2002 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 prototyping 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.

3. Dr. Lotfi K. Gaafar 2002 Rapid prototyping worldwide

4. Dr. Lotfi K. Gaafar 2002 Rapid Prototyping  What is Rapid Prototyping? A CAD technique to allow “Automatic” creation of a physical model or prototype from a 3-D model. Create a 3-D “Photocopy” of a part.  Computer Real life  Why use Rapid Prototyping? Decreases lead time Facilitates concurrent engineering Allows visualization of more ideas

5. Dr. Lotfi K. Gaafar 2002 Rapid Prototyping Traditional Methods CAD Only RP&M Rapid Prototyping Enables the Making of Enables the Making of Physical Models From Physical Models From Computer-Aided Design Computer-Aided Design (CAD) Data (CAD) Data

6. Dr. Lotfi K. Gaafar 2002 BASIC PROCESS All RP techniques employ the same basic five-step process 1 3 2 5 4

7. Dr. Lotfi K. Gaafar 2002 The principle of model generation by Rapid Prototyping

8. Dr. Lotfi K. Gaafar 2002 The 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.

9. Dr. Lotfi K. Gaafar 2002 1.Creation a CAD model of the design  First, the object to be built is modeled using a Computer-Aided Design (CAD) software package.  Solid modelers, such as Pro/ENGINEER, CATIA tend to represent 3-D objects more accurately than wire-frame modelers such as AutoCAD, and will therefore yield better results.  This process is identical for all of the RP build techniques.

10. Dr. Lotfi K. Gaafar 2002 2.Conversion CAD model to STL Format  To establish consistency, the STL (stereolithography, the first RP technique) format has been adopted as the standard of the rapid prototyping industry.  The second step, therefore, is to convert the CAD file into STL format. This format represents a three-dimensional surface as an assembly of planar triangles  STL files use planar elements, they cannot represent curved surfaces exactly. Increasing the number of triangles improves the approximation.

11. Dr. Lotfi K. Gaafar 2002  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 number of layers from 0.01 mm to 0.7 mm thick, depending on the build technique.  The program may also generate an auxiliary structure to support the model during the build. Supports are useful for delicate features such as overhangs, internal cavities, and thin-walled sections. 3.Slice the STL file into thin cross-sectional layers

12. Dr. Lotfi K. Gaafar 2002 4.Layer by Layer Construction  The fourth step is the actual construction of the part.  RP machines build one layer at a time from polymers, paper, or powdered metal.  Most machines are fairly autonomous, needing little human intervention.

13. Dr. Lotfi K. Gaafar 2002  The final step is post-processing. This involves removing the prototype from the machine and detaching any supports.  Some photosensitive materials need to be fully cured before use  Prototypes may also require minor cleaning and surface treatment.  Sanding, sealing, and/or painting the model will improve its appearance and durability. 5.Clean and Finish

14. Dr. Lotfi K. Gaafar 2002 Rapid Prototyping Processes 1.SLA --- Stereolithography 2..FDM --- Fused Deposition Modeling 3.SLS --- Selective Laser Sintering 4.LOM --- Laminated Object Manufacturing And Others…

15. Dr. Lotfi K. Gaafar 2002 1.Stereolithography  Stereolithography is the most widely used RP-technology.  It can produce highly accurate and detailed polymer parts.  SLA was the first RP-process, introduced in 1988 by 3D Systems Inc.  SLA uses a low-power, highly focused UV laser to produce a three dimensional object in a vat of liquid photosensitive polymer.

16. Dr. Lotfi K. Gaafar 2002 1.Stereolithography

17. Dr. Lotfi K. Gaafar 2002 1.Stereolithography

18. Dr. Lotfi K. Gaafar 2002 1.Stereolithography  The technique builds three-dimensional models from liquid photosensitive polymers that solidify when exposed to ultraviolet light.

19. Dr. Lotfi K. Gaafar 2002 Application Range  Parts used for functional tests  Manufacturing of medical models  Form –fit functions for assembly tests Advantages  Possibility of manufacturing parts which are impossible to be produced conventionally in a single process  Can be fully automized and no supervision is required.  High Resolution  No geometric limitations Disadvantages  Necessity to have a support structure  Require labor for post processing and cleaning. 1.Stereolithography

20. Dr. Lotfi K. Gaafar 2002 2.Fused Deposition Modeling  FDM was developed by Stratasys.  In this process, a plastic or wax material is extruded through a nozzle that traces the part´s cross sectional geometry layer by layer.

21. Dr. Lotfi K. Gaafar 2002 2.Fused Deposition Modeling

22. Dr. Lotfi K. Gaafar 2002 2.Fused Deposition Modeling  (FDM) is a solid-based rapid prototyping method that extrudes material, layer-by-layer, to build a model.  A thread of plastic is fed into an extrusion 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.

23. Dr. Lotfi K. Gaafar 2002 Rapid prototyping Processes- FDM M/C

24. Dr. Lotfi K. Gaafar 2002 Application Range  Conceptual modeling  Fit, form applications and models for further manufacturing procedures  Investment casting and injection molding 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. 2.Fused Deposition Modeling

25. Dr. Lotfi K. Gaafar 2002 3.Selective Laser Sintering

26. Dr. Lotfi K. Gaafar 2002 3.Selective Laser Sintering

27. Dr. Lotfi K. Gaafar 2002 3.Selective Laser Sintering

28. Dr. Lotfi K. Gaafar 2002 3.Selective Laser Sintering The process  The process operates on the layer-by-layer principle. At the beginning a very thin layer of heat fusible powder is deposited in the working space container. The CO2-laser sinters the powders.  The sintering process uses the laser to raise the temperature of the powder to a point of fusing without actually melting it. As the process is repeated, layers of powder are deposited and sintered until the object is complete.

29. Dr. Lotfi K. Gaafar 2002 3.Selective Laser Sintering  The powder is transferred from the powder cartridge feeding system to the part cylinder (the working space container) via a counter rolling cylinder, a scraper blade or a slot feeder.  In the not sintered areas, powder remains loose and serves as natural support for the next layer of powder and object under fabrication. No additional support structure is required.  An SLS system contains also an atmosphere control unit that houses the equipment to filter gas recirculated from the process chamber. It also maintains a set temperature on the air flowing into the process chamber.

30. Dr. Lotfi K. Gaafar 2002 Application Range  Visual Representation models  Functional and tough prototypes  cast metal parts 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 Disadvantages  During solidification, additional powder may be hardened at the border line.  The roughness is most visible when parts contain sloping (stepped) surfaces. 3.Selective Laser Sintering

31. Dr. Lotfi K. Gaafar 2002 4.Laminated Object Manufacturing The process:  The build material (paper with a thermo-setting resin glue on its under side) is stretched from a supply roller across an anvil or platform to a take- up roller on the other side.  A heated roller passes over the paper bonding it to the platform or previous layer.  A laser, focused to penetrate through one thickness of paper cuts the profile of that layer. The excess paper around and inside the model is etched into small squares to facilitate its removal.

32. Dr. Lotfi K. Gaafar 2002 4.Laminated Object Manufacturing

33. Dr. Lotfi K. Gaafar 2002 4.Laminated Object Manufacturing

34. Dr. Lotfi K. Gaafar 2002 Application Range  Visual Representation models  Large Bulky models as sand casting patterns. 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. 4.Laminated Object Manufacturing

35. Dr. Lotfi K. Gaafar 2002 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 are 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. Rapid prototyping Processes

36. Dr. Lotfi K. Gaafar 2002 Rapid Prototyping Products

37. Dr. Lotfi K. Gaafar 2002 Examples of parts made by rapid prototyping processes

38. Dr. Lotfi K. Gaafar 2002 Problems with Rapid Prototyping  Part accuracy Staircase appearance for a sloping part surface due to layering Shrinkage and distortion of RP parts  Limited variety of materials in RP Mechanical performance of the fabricated parts is limited by the materials that must be used in the RP process

39. Dr. Lotfi K. Gaafar 2002 THANK YOU FOR YOUR ATTENTION ! HAVE A NICE DAY !