JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV ADDITIVE MANUFACTURING Previous Question Paper (July/August - 2022 - R18)

Prototyping is the process of creating an early sample or model of a product to test concepts, verify designs, and identify potential failures before full-scale production. It serves as a bridge between design and manufacturing, allowing for iterative refinement.

Historically, prototyping evolved from manual craftsmanship, where skilled workers created models using wood, clay, or metal. The industrial revolution introduced machining and casting, which were time-consuming and expensive for one-off models. The shift toward modern Additive Manufacturing (AM) began in the 1980s with the invention of Stereolithography (SLA) by Chuck Hull, who patented the process in 1986. This marked the transition from subtractive methods to layer-by-layer material deposition. Subsequent developments included Selective Laser Sintering (SLS) and Fused Deposition Modeling (FDM) in the late 1980s and early 1990s, which revolutionized rapid prototyping by enabling the production of complex geometries directly from 3D CAD data without the need for specialized tooling.

Automated processes in additive manufacturing follow a systematic digital workflow that minimizes human intervention. The fundamental steps are:

• CAD Modeling: The process begins with the creation of a 3D solid model using Computer-Aided Design software.
• Conversion to STL: The CAD model is converted into a standard tessellation language (STL) file, which approximates the surface geometry using a mesh of triangles.
• Slicing: The software slices the 3D model into thin horizontal 2D cross-sections (layers). This step generates the G-code or toolpath instructions for the machine.
• Machine Setup: The build platform is prepared, and material (powder, filament, or resin) is loaded. Parameters such as layer thickness, scan speed, and temperature are defined.
• Layer-by-Layer Fabrication: The machine automatically deposits or solidifies material layer by layer according to the sliced data. This involves automated control of lasers, extruders, or print heads.
• Post-Processing: Once the build is complete, the part is removed, cleaned, and subjected to finishing processes like support removal, curing, or surface polishing to achieve the final functional state.