# 3D Printing and Modeling

# Rapid Prototyping

Rapid Prototyping is a group of techniques used to fabricate a model of a physical part or assembly using 3-dimensional computer aided design (CAD). Rapid prototyping usually includes 3D printing and additive layer manufacturing technology.

In rapid prototyping process, a valid geometric 3D model is created using CAD software. The CAD model is converted into geometrical or mathematical model which gets stored in .STL format. Now, this geometrical form of the model is sliced into layers and the layers are scanned into lines which generates the trajectory for toolpath.

Some techniques of rapid prototyping are given below:

  1. 3D Printing
  2. Fused Deposition Modelling(FDM)
  3. Selective Laser Sintering(SLS)
  4. Stereo Lithography(SLA)

# 3D Printing

3D printing is the action or process of making a physical object from a three-dimensional model by laying down many thin layers of a material in succession. 3D printing is the additive manufacturing process in which object is created by successive addition of material layer-by-layer instead of traditional material removal processes. 3D printing enables us to produce complex shapes using less material than traditional manufacturing methods.

# General Principles:

# Modeling

3D printable models are created using CAD softwares or 3D scanners. The models allow us to improve design, reduce errors and complete control over the object before it is formed. The model is stored in .STL format.

# Printing

The .STL file is processed in a slicer software, which converts model into series of thin layers. It also creates a G-code file containing instructions for pathways tailored to a specific 3D printer. This G code instructs 3D printer during the printing process.

# Finishing

The printed part is surface finished using different physical or chemical processes.So, The printed objects are desired to be slightly oversized to accommodate finishing.

# 3D printer

3D printer is a machine used for 3D printing of a model. It consists of three movable caretsian axes along x- , y- and z- directions. An extruder with hot end and a nozzle is attached to one of the axis. 3D printing filament is passed into the extruder which is heated to its melting temperature by the hot end. The melted filament is pushed out of the nozzle into very thin extrusion. This extrusion is deposited onto the print bed whose pathways are given by coordinated motion along each axes determined according to the G-code given to the printer. The filaments usually used in 3D printer are made up of PLA or ABS material.The print gets deposited layer by layer until the complete model is printed.

Melting temperature for PLA: 173 ℃
Melting temperature for ABS: 105 ℃

# Modeling Software:

AutoCAD, Fusion360, Solidworks, CATIA ,etc.

# Slicing Software:


# Applications:

3D printing techniques significantly reduce the time and cost of developing prototypes. The material requirement is substantially reduced due to additive manufacturing. 3D printing entered into much greater extent since 2010. This technology has touched each and every aspect of manufacturing till date. Additive manufacturing techniques are being used in clothing, fooding and daily production. In large scale, this technology is changing the aerospace, mechanical engineering, civil engineering, product development, automobile technologies and biotechnology.