(SEM VIII) THEORY EXAMINATION 2016-17 ADDITIVE MANUFACTURING

SECTION A (Brief Answers)

Classification of Additive Manufacturing
Additive manufacturing can be classified into vat photopolymerization, material extrusion, powder bed fusion, binder jetting, material jetting, sheet lamination, and direct energy deposition. These categories are based on the method of material deposition and energy source used.

Additive Engineering vs CNC Machining
Additive manufacturing builds parts layer by layer by adding material, while CNC machining removes material from a solid block. AM reduces material waste and enables complex geometries, whereas CNC provides high dimensional accuracy and surface finish.

STL File
An STL (Stereolithography) file is a standard file format used in AM that represents the 3D surface geometry of a part using triangular facets.

AM Process Chain
The AM process chain includes CAD modeling, conversion to STL file, slicing, tool path generation, layer-by-layer fabrication, post-processing, and final inspection.

Sheet Lamination Process
Sheet lamination is an AM process where thin sheets of material are bonded layer by layer and cut to shape. Examples include Laminated Object Manufacturing (LOM).

DED Systems
Direct Energy Deposition (DED) systems use focused thermal energy such as laser or electron beam to melt and deposit material simultaneously. It is used for repair and large metal parts.

Quality of Additive Manufacturing
Quality in AM refers to dimensional accuracy, surface finish, mechanical properties, and structural integrity of printed parts.

Engineering Design Rules in AM
Design rules include minimizing support structures, maintaining proper wall thickness, optimizing orientation, and considering layer resolution.

Applications of AM
Applications include aerospace components, medical implants, automotive parts, rapid prototyping, tooling, and customized products.

Future Directions in AM
Future trends include multi-material printing, bio-printing, large-scale construction printing, and improved material properties.

SECTION B (Medium Length Answers)

Evolution from Rapid Prototyping to AM
Rapid prototyping initially focused on creating physical models for design validation. Over time, advancements in materials and precision allowed production of functional end-use parts. This transition expanded AM from prototyping to full-scale manufacturing.

Need for Post-Processing in Powder-Based AM
Post-processing is required to remove excess powder, improve surface finish, enhance mechanical properties, and perform heat treatment. It ensures dimensional accuracy and part strength.

Aerosol Printing and Bioplotter
Aerosol printing deposits fine material droplets for electronics and microstructures. Bioplotter is used in biomedical applications to print living tissues and scaffolds for regenerative medicine.

Design of AM Systems
AM systems include material feed system, energy source, motion control system, and control software. Proper integration ensures accurate layer deposition and dimensional control.

Hybrid Technologies in AM
Hybrid technologies combine additive and subtractive processes in a single machine. This improves surface finish and dimensional accuracy while maintaining design flexibility.

Potential and Prospectus of AM Design
AM enables lightweight structures, topology optimization, and mass customization. It reduces tooling cost and supports decentralized manufacturing.

Software Issues in AM
Major software issues include STL file errors, slicing inaccuracies, support generation challenges, and simulation of thermal distortion.

Secondary Rapid Prototyping Process
Secondary processes involve finishing, painting, machining, or coating to enhance appearance and mechanical performance.

SECTION C (15-Mark Style Answers)

Impact of AM on New Product Development
AM significantly reduces product development time by enabling quick prototyping and testing. Designers can rapidly modify designs without tooling changes. It supports customization and reduces production cost for small batches. This accelerates innovation and market entry.

Powder Based Fusion Process
Powder bed fusion uses laser or electron beam to selectively melt powder layer by layer. It produces high-strength metal and polymer components with good precision.

Material Jetting
Material jetting deposits droplets of liquid photopolymer, which are cured using UV light. It offers high surface finish and multi-material capability.

Direct Energy Deposition Process
DED uses focused energy to melt material as it is deposited. It is suitable for repair and manufacturing of large metal components.

Eight Steps in Additive Manufacturing
The eight steps include conceptualization, CAD modeling, STL conversion, file transfer to machine, machine setup, building process, removal and post-processing, and inspection/testing.