Rapid Prototyping in Mechanical Engineering | Classification of Rapid Prototyping.

-

Classification of Rapid Prototyping

These are the following classification that are discussed below further in details-
  1. Liquid - Based Rapid Prototyping
  2. Solid - Based Rapid Prototyping
  3. Powder-Based Rapid Prototyping
  4. Extrusion Based Rapid Prototyping
  5. Sheet Based Rapid Prototyping
  6. Binder Jetting Process

1. Liquid Based Rapid Prototyping:

  • In liquid based Rapid Prototyping, liquid resign is used and solidify layer by layer. For Example - SLA (Stereolithography Apparatus).
  • The Main features of this RP process are High accuracy, smooth surface finish, costly material.

2. Solid Based Rapid Prototyping:

  • In solid based RP solid material (sheet / filament / wire) is used and after cutting layer by layer to produce product. For Example FDM, LOM.
  • The Main features are low cost, easy operation, medium accuracy.

3. Powder Based Rapid Prototyping:

  • In Powder based RP, powder is fused in binder or laser. For Example SLS, SLM, EBM.
  • The Main features are strong parts, metal component possible, industrial use.

4. Extrusion Based Rapid Prototyping: 

  • In extrusion based RP material is extrude from nozzle and making layer. For Example FDM.
  • The Main features are used of recyclable thermoplastic material and widely used in desktop 3D Printing.

5. Sheet Based Rapid Prototyping:

  • In sheet based RP, thin sheets are cut and making bond to make models. For Example LOM
  • The Main features are most fast RP process and used of lower cost materials like paper, plastics, metal sheets used.

6. Binder Jetting Process:

  • In binder jetting process powder bed spray by liquid binder to make models. For Example 3DP(3 Dimensional Printing)
  • The Main features are color printing possible and also post processing required.

Rapid Prototyping processes

1. STEREOLITHOGRAPHY APPRATUS (SLA)
  • Definition: Stereolithography Apparatus is a additive manufacturing process where, through leaser beam solidifying photosensitive liquid resin layer-by-layer to make any model.
  • Key points are that the control unit slices the model and slices under cross section of 0.025 to 0.5mm.
    Components of SLA:
  1. UV Laser
  2. Galvanometer mirror
  3. Resin Vat
  4. Build Platform
  5. Control System
    Working Process of Stereolithography apparatus:
    1. Making of CAD Model - 
  • A 3D CAD model is made through relevant CAD software.
  • after virtual model is completed, Converting it into STL (stereolithography) file.
    2. Liquid resin vat -
  • A tank called vat is filled with liquid photopolymer resign.
  • The resign is UV sensitive.
  • The resin is thermosetting polymer.
    3. UV laser scanning -
  • UV laser scanning the surface.
  • The place where UV concentrated causes resin to solidify.
  • Solidification can be done by polymerization reaction.
    4. Platform movement -
  • By completing one layer platform moves downward.
  • Fresh layer liquid will come above.
  • In inverted SLA platform moves in upward.
    5. Repetition -
  • Whole process repeat itself up to part completation.
    6. Post processing -
  • Remove part from resign.
  • post curing in UV oven.
  • Removing supports.
Materials used in SLA: 
    In SLA generally used of materials like Epoxy based photopolymers and Acrylic based                            photopolymers.
Support in SLA:
  • Compulsory supports for over hanging parts.
  • Supports are made by same resign.
  • Supports are generated by automatic softwarel.