Computer Aided Design
CAD programs (AutoCAD, Inventor, Revit, CATIA, SolidWorks, SketchUp) allow engineers to make precisely scaled drawings. These drawings can be used to manufacture equipment and construct infrastructure. CAD drawing allows designers to display designs with complete specifications and detail. Orthographic views (top, bottom, side, front, back, etc.) can be used to document every aspect of the technical drawing needed for production. Isometric views can be used to interpret the final 3D representation of the product.
This lab will train the components of CAD software, file formats, and the basics of 3D drafting. It will provide enough information to learn how to create drawings, as well as explore the other tools and functions.
3D Printing
3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer control, with material being added together (such as plastics, liquids or powder grains being fused), typically layer by layer.
The various additive manufacturing techniques are as follows
This lab will cover two types of additive manufacturing techniques
- Materials Based – Fused Deposition Modeling
- Vat Polymerization – Stereo lithography
Fused Deposition Modeling also known as Fused Filament Fabrication is an additive manufacturing process that contains a plastic filament or metal wire which is unwound from a coil and supplies material to an extrusion nozzle which can turn the flow on and off. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism. The model or part is produced by extruding small beads of thermoplastic material to form layers as the material hardens immediately after extrusion from the nozzle. The schematic diagram of fused deposition modeling is shown below. Stereo lithography is an additive manufacturing process which employs a vat of liquid ultraviolet curable photopolymer resin and an ultraviolet laser to build part layers one at a time. For each layer, the laser beam traces a cross-section of the part pattern on the surface of the liquid resin. Exposure to the ultraviolet laser light cures and solidifies the pattern traced on the resin and joins it to the layer below. Scanning speeds ~ 500 to 2500 mm/s. Thinner layers provide better resolution and more intricate shapes; but processing time is longer. Starting materials are liquid monomers epoxies, acrylates (brittle). The following figure shows the schematic diagram of stereo lithography process at the start of the process, in which the initial layer is added to the platform and after several layers have been added so that the part geometry gradually takes form.
Fused Deposition Modeling
Stereolithography
Joses Samuel Sasthriga S
Technical Illustrator, IPC DepartmenT
Boeing, Chennai.
Navin Sales Michael J
Piping Design Engineer
SAIPEM projects private limited, Chennai
