Introduction to Additive Manufacturing and Rapid Prototyping

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Questions and Answers

What is the primary classification of Rapid Prototyping Systems based on?

The application of the prototype

The method of prototyping

The type of material used in the final product

The initial form of its material (correct)

What is the process used to convert liquid into solid state in liquid-based RP systems?

Fusing

Curing (correct)

Melting

Sintering

What is the material used in Laminated Object Manufacturing (LOM) prototyping technology?

Photopolymer

Thermoplastics

Titanium alloys

Paper (correct)

What is the type of laser used in the Laser Engineered Net Shaping (LENS) process?

Nd: YAG laser Signup and view all the answers

What is the environment in which the fabrication process takes place in the LENS process?

Low-pressure argon chamber Signup and view all the answers

What is the primary purpose of the motion system in the LENS process?

To move the laser beam horizontally and laterally Signup and view all the answers

What is the purpose of tilting the object/cluster by 10 to 15 degrees in LOM, SLS, SGC, and 3D printing?

To avoid any surface becoming horizontal Signup and view all the answers

What is the primary function of the hot roller in the LOM process?

To stick the paper layer to the previous layer Signup and view all the answers

What is a major limitation of the LOM process?

Grid cutting takes much more time than object cutting Signup and view all the answers

What is the primary difference between 3D printing and SLS?

The use of a binder liquid in 3D printing Signup and view all the answers

What is the function of the nozzle in FDM?

To deposit the molten material Signup and view all the answers

Why are explicit support structures required in FDM?

To provide additional support for the model Signup and view all the answers

What is a major advantage of the LENS process?

Production of fully dense metal parts with superior material properties Signup and view all the answers

What is a limitation of the DMD process?

Limited to producing only metal parts Signup and view all the answers

What is a benefit of the DLD process?

Ability to add material to existing components for service and repair Signup and view all the answers

What is a drawback of building overhang parts using traditional DLD or RP processes?

Support structures are very often needed Signup and view all the answers

What is a challenge of the 'Cut and then paste' approach in LOM?

Handling the cut pieces is difficult Signup and view all the answers

What is an advantage of the 'Paste and then cut' approach in LOM?

Handling is easy Signup and view all the answers

What is the primary goal of companies in the current marketplace?

To respond quickly to changing customer demands Signup and view all the answers

What is a prototype?

A model from which further models and eventually the final product will be derived Signup and view all the answers

What is the term 'rapid prototyping' referring to?

A process for rapidly creating a system or part representation Signup and view all the answers

What are alternative names for Rapid Prototyping?

Additive Manufacturing, Layer Manufacturing, Direct CAD Manufacturing, Solid Freeform Fabrication Signup and view all the answers

What is the main difference between traditional prototyping and rapid prototyping?

The time consumed in the process Signup and view all the answers

What is the main advantage of rapid prototyping over traditional prototyping?

It gives better quality Signup and view all the answers

What is the primary method of depositing material in the Fused Deposition Modeling process?

Small droplets are shot by a nozzle onto a previously formed layer Signup and view all the answers

What is a major advantage of Fused Deposition Modeling over other RP processes?

It can be used in an office environment and is very easy to use Signup and view all the answers

What is a limitation of Electron Beam Melting (EBM) compared to other Powder Bed Fusion (PBF) processes?

It can only be used with metal powders and has a larger heat-affected zone Signup and view all the answers

What is the primary difference between Electron Beam Melting (EBM) and other Powder Bed Fusion (PBF) processes?

EBM uses an electron beam to fuse powder particles, whereas other PBF processes use a laser beam Signup and view all the answers

What is the purpose of the small mirror in the Selective Laser Sintering (SLS) process?

To position the laser beam and deflect it in two directions Signup and view all the answers

Why is it not necessary to use explicit support structures in Selective Laser Sintering (SLS)?

Because the powder itself acts as support and allows for complex geometries Signup and view all the answers

What is the purpose of using an inert environment in the selective laser sintering process?

To minimize fire hazards due to the high activation of fine particles Signup and view all the answers

What is the advantage of using selective laser sintering over other rapid prototyping techniques?

It is suitable for making injection molding tools Signup and view all the answers

What is the purpose of copper impregnation in the selective laser sintering process?

To improve the polishability of the part Signup and view all the answers

What is the limitation of selective laser sintering in terms of surface finish?

It is dependent on the particle size of the powder Signup and view all the answers

What is the purpose of the small mirror in the stereo lithography process?

To position the laser beam Signup and view all the answers

What is the purpose of the post-cure apparatus in the stereo lithography process?

To complete the polymerization of the part Signup and view all the answers

What is the pattern used for area filling in the stereo lithography process?

Grid pattern Signup and view all the answers

What is the purpose of the contra-rotating roller in the selective laser sintering process?

To level the layer of powder Signup and view all the answers

What is the advantage of using stereo lithography over other rapid prototyping techniques?

It has very low inertia and hence high speed and accuracy Signup and view all the answers

What is the purpose of the support structures in the stereo lithography process?

To provide additional support to the part during fabrication Signup and view all the answers

Study Notes

Introduction to Rapid Prototyping

Rapid prototyping (RP) is a class of technologies that create physical models from Computer-Aided Design (CAD) data.
Alternative names for RP include Additive Manufacturing, Layer Manufacturing, Direct CAD Manufacturing, and Solid Freeform Fabrication.

Traditional Prototyping vs. Rapid Prototyping

Traditional prototyping involves building a model from clay, carving from wood, bending wire, or using thermoplastic, photopolymer, metals, paper, or titanium alloys.
Traditional prototyping methods are time-consuming, lack quality, and cannot effectively evaluate alternative design concepts.
Rapid prototyping methods are faster, more accurate, and can effectively evaluate design concepts.

Classification of Rapid Prototyping Systems

RP systems can be classified into three categories: liquid-based, solid-based, and powder-based.

Liquid-Based RP Systems

Liquid-based RP systems include:
- 3D Systems' Stereo lithography Apparatus (SLA)
- Cubital's Solid Ground Curing (SGC)
- Sony's Solid Creation System (SCS)
- CMET's Solid Object Ultraviolet-Laser Printer (SOUP)
- Autostrade's E-Darts
- Teijin Seiki's Soliform System
- Meiko's Rapid Prototyping System for the Jewelry Industry
- Denken's SLP
- Mitsui's COLAMM
- Fockele & Schwarze's LMS
- Light Sculpting
- Aaroflex
- Rapid Freeze
- Two Laser Beams
- Micro fabrication

Additive Manufacturing Techniques

1. Laser Engineered Net Shaping (LENS)
- Builds components in an additive manner from powdered metals using a Nd:YAG laser.
- Produces fully dense metal parts with good metallurgical properties.
- Advantages: superior material properties, complex parts, and reduced post-processing requirements.
- Disadvantages: limited materials, large physical unit size, and high power consumption.
1. Direct Metal Deposition (DMD)
- Uses a laser to weld air-blown streams of metallic powders into custom parts.
- Can produce fully dense metal parts with good metallurgical properties.
- Advantages: ability to fabricate fully dense metal parts, efficient, and reduces production costs.
- Disadvantages: limited to building overhang parts and requires support structures.
1. Sheet Lamination (Laminated Object Manufacturing (LOM)
- Builds parts by laminating layers of paper or other materials.
- Advantages: fast, inexpensive, and ideal for patterns for casting.
- Limitations: grid cutting takes time, decubing is time-consuming, and horizontal surfaces pose problems.
1. 3D Printing
- Similar to SLS, except that a binder liquid is sprayed in selected regions.
- Can use a wide variety of powders.
- Advantages: fast, inexpensive, and ideal for concept models.
- Limitations: requires sintering, and supports are required.
1. Fused Deposition Modeling (FDM)
- Uses molten material to build parts.
- Advantages: uses any thermoplastic material, easy to remove support, and inexpensive.
- Limitations: slow, not very accurate, and requires explicit support structures.
1. Electron Beam Melting (EBM)
- Uses an electron beam to induce fusion between metal powder particles.
- Advantages: fast, efficient, and can process conductive materials.
- Limitations: can only be used with conductive materials, and has a larger heat-affected zone.
1. Selective Laser Sintering (SLS)
- Uses a laser to fuse together metal powder particles.
- Advantages: fast, uses a wide variety of powders, and ideal for making injection molding tools.
- Limitations: surface finish is poor, and Z accuracy is poor.
1. Photopolymerization (Stereo Lithography (SLA)
- Uses a laser to polymerize liquid photopolymer.
- Advantages: fast, accurate, and ideal for making prototypes.
- Limitations: requires explicit support structures, and post-processing is required.

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Description

Learn about the basics of additive manufacturing, rapid prototyping, and its applications, limitations, and classification. Compare traditional prototyping with rapid prototyping.