Manufacturing Processes Chapter 3 & 4

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Questions and Answers

Architectural modeling designs only depict the exact production of the final design.

False (B)

What is becoming more common in additive manufacturing processes?

Color and multiple material systems

Standardized software processes are needed as direct digital manufacturing becomes more ______.

common

Match the following types of manufacturing processes with their descriptions:

<p>Additive manufacturing = Building up material layer by layer Direct digital manufacturing = Creating physical products directly from digital files Subtractive manufacturing = Removing material from a solid block Hybrid manufacturing = Combination of additive and subtractive processes</p> Signup and view all the answers

The STL format describes the CAD model in terms of color and texture.

<p>False (B)</p> Signup and view all the answers

Name one application area of additive manufacturing that does not involve conventional CAD modeling.

<p>Medical modeling</p> Signup and view all the answers

The process of converting a CAD model to STL involves approximating the surface of the model with a series of ______.

<p>triangular facets</p> Signup and view all the answers

Match the following types of AM machines with their characteristics:

<p>Solid sheets = Layer materials that are cut then bonded Powder-based systems = Utilize powdered materials for printing Molten material systems = Extrude heated materials to create objects Photopolymer based systems = Use liquid resin cured by light</p> Signup and view all the answers

Energy density is a factor to consider in metal additive manufacturing.

<p>True (A)</p> Signup and view all the answers

List two design considerations for additive manufacturing.

<p>Part orientation, Removal of supports</p> Signup and view all the answers

All AM machines require the same setup parameters regardless of the material used.

<p>False (B)</p> Signup and view all the answers

What may be necessary for some parts before they are built?

<p>Shrinkage or coating allowances</p> Signup and view all the answers

The first few stages of the building process are ______.

<p>semi-automated</p> Signup and view all the answers

Match the actions with their descriptions:

<p>Build phase = Layer-based manufacturing process Machine setup = Adjusting specific parameters based on material Verify the part is correct = Ensures specifications are met Removal and cleanup = Preparing the part for final use</p> Signup and view all the answers

All AM machines will alert the user when the build is complete or when there is no material remaining.

<p>True (A)</p> Signup and view all the answers

What might some unusual cases require concerning STL files?

<p>Segmentation of STL files</p> Signup and view all the answers

Solid sheets used in lamination methods require support structures during processing.

<p>False (B)</p> Signup and view all the answers

What is one common issue experienced by paper-based systems?

<p>Handling problems</p> Signup and view all the answers

Part orientation, removal of supports, and hollowing out parts are all considerations for ______.

<p>Additive Manufacturing (AM)</p> Signup and view all the answers

Match the following issues with their relevant considerations:

<p>Material exposure = Moisture and light Recycling material = Offline loading using software Laser technology = Fragility and monitoring Equipment maintenance = Clean environments</p> Signup and view all the answers

Interlocking features are considered an advanced design element in conventional CAD modeling.

<p>False (B)</p> Signup and view all the answers

Name one application area for medical modeling that does not involve conventional CAD.

<p>CT or MRI</p> Signup and view all the answers

Post-processing is an automatic stage that requires no manual effort.

<p>False (B)</p> Signup and view all the answers

What may happen to parts created through additive manufacturing under mechanical stress?

<p>They may fail due to small voids or bubbles trapped inside them.</p> Signup and view all the answers

Newer resins in photopolymer-based systems degrade rapidly without proper UV protection.

<p>True (A)</p> Signup and view all the answers

Match the terms related to additive manufacturing with their definitions:

<p>Void = An empty space within the material that can cause structural weakness Support Structures = Temporary frameworks that prevent part warping during production Post-processing = The stage involving finishing and refining parts after production Anisotropic = Material properties that vary in different directions</p> Signup and view all the answers

Manual skill is unnecessary for the support removal stage in additive manufacturing.

<p>False (B)</p> Signup and view all the answers

Thicker layers in additive manufacturing lead to more precise parts.

<p>False (B)</p> Signup and view all the answers

What are some post-processing tasks that can benefit from the use of power tools?

<p>Abrasive finishing, polishing, or application of coatings.</p> Signup and view all the answers

What must be considered during post-processing that involves heat in additive manufacturing?

<p>Heat resistance or melting temperature of the material.</p> Signup and view all the answers

In powder-based systems, a bed of powder is deposited ______.

<p>layer-by-layer</p> Signup and view all the answers

Match the following types of additive manufacturing systems with their characteristics:

<p>Binder printing = Can create colored parts Photopolymer-Based Systems = Use support from the same material as the part Powder-Based Systems = No need to use supports FDM Dimension = Has a nominal layer thickness of 0.254 mm</p> Signup and view all the answers

In additive manufacturing, the initial part of the ______ stage is the cleanup stage.

<p>post-processing</p> Signup and view all the answers

What material processing category can affect the time and resources required in additive manufacturing?

<p>Use of different materials.</p> Signup and view all the answers

Photopolymerization reaction rates are independent of their radiance and exposure time.

<p>False (B)</p> Signup and view all the answers

What is the purpose of using photo initiators in photopolymerization?

<p>To initiate the polymerization reaction upon exposure to light.</p> Signup and view all the answers

The ______ pattern is one of the scan patterns used in vector scan VP machines.

<p>WEAVE</p> Signup and view all the answers

Match the following components with their functions in vat photopolymerization:

<p>Monomer formulations = Building the polymer structure Laser-resin interaction = Curing the resin with laser Photospeed = Rate of reaction based on exposure Interpenetrating polymer network = Enhanced mechanical properties</p> Signup and view all the answers

Visible light is predominantly used in the microelectronic industry.

<p>False (B)</p> Signup and view all the answers

What is a primary benefit of the two-photon approach in photopolymerization?

<p>Recoat is unnecessary as the part is fabricated below the resin surface.</p> Signup and view all the answers

In the ______ scan approach, scanning laser beams are needed.

<p>vector</p> Signup and view all the answers

Match the following photopolymerization configurations with their characteristics:

<p>Resin application = Reapplication of resin for each new layer Two-photon = High resolution with no recoating needed Mask projection = Layer-wise approach with large radiation beam Vector scan = Point-wise approach with recoating required</p> Signup and view all the answers

Photopolymers were developed in the 1980s.

<p>False (B)</p> Signup and view all the answers

Who is credited with the discovery of producing solid polymer patterns through UV curing in the mid-1980s?

<p>Charles Hull</p> Signup and view all the answers

Photo-curable resins are often used in ______ to seal deep grooves in teeth.

<p>dentistry</p> Signup and view all the answers

Match the following types of radiation with their applications incuring photopolymers:

<p>Gamma rays = Curing of photopolymers for coatings Visible light = Some photopolymerization systems UV radiation = 3D printing processes X-rays = Medical imaging and treatment</p> Signup and view all the answers

Current stereolithography materials possess high impact strength and durability compared to injection molded thermoplastics.

<p>False (B)</p> Signup and view all the answers

What is the minimum size of a hardened polymer unit produced in microfabrication applications?

<p>5 µm x 5 µm x 3 µm</p> Signup and view all the answers

The accuracy of the SLA-250 is ______.

<p>0.002 in/in</p> Signup and view all the answers

Match the following characteristics with their corresponding technologies:

<p>Mask Projection VP = Speed advantage over laser scan SL Two-Photon VP = Used primarily for high-resolution microfabrication SLA-250 = Precision of 0.002 in/in Microsterolithography = 5-µm spot size of the UV beam</p> Signup and view all the answers

Mask projection technologies are less efficient than laser scanning for SLA processes.

<p>False (B)</p> Signup and view all the answers

What constrains the chemistry of commercially used photopolymers?

<p>Acrylates and epoxies</p> Signup and view all the answers

Photopolymers are primarily used as photoresists in the biomedical field.

<p>False (B)</p> Signup and view all the answers

What is the role of a photoinitiator in photopolymer chemistry?

<p>To convert physical energy of light into chemical energy.</p> Signup and view all the answers

In laser scan vat photopolymerization, a UV laser selectively solidifies a liquid photopolymer resin to create ______.

<p>solid parts</p> Signup and view all the answers

Match the following types of polymerization with their respective materials:

<p>Free radical polymerization = Acrylate Both types = Acrylate and Epoxy Cationic polymerization = Epoxy Vinylether polymerization = Vinylether</p> Signup and view all the answers

Acrylates polymerize through a radical mechanism, while epoxides polymerize through a cationic mechanism.

<p>True (A)</p> Signup and view all the answers

What is the term for the network formation that occurs when acrylates and epoxides polymerize?

<p>Interpenetrating polymer network formation</p> Signup and view all the answers

Powder Bed Fusion processes include only metallic materials.

<p>False (B)</p> Signup and view all the answers

What is one of the main powder fusion mechanisms mentioned in Powder Bed Fusion processes?

<p>Liquid-phase sintering</p> Signup and view all the answers

The first PBF process, Selective Laser Sintering, was developed at the ______.

<p>University of Texas at Austin</p> Signup and view all the answers

Match the following powder fusion mechanisms with their descriptions:

<p>Full melting = Complete melting of powder particles Solid-state sintering = Fusion without melting of particles Chemically induced sintering = Fusion induced by chemical reactions Liquid-phase sintering = Fusion through partial melting</p> Signup and view all the answers

The activation energy of a catalyzed reaction is larger than that of an un-catalyzed reaction.

<p>False (B)</p> Signup and view all the answers

What is the rate constant found when the temperature is 289K, Activation Energy is 200kJ/mol, and pre-exponential factor is 9 M-1s-1?

<p>6.37 x 10^-36 M-1s-1</p> Signup and view all the answers

Flashcards

Laser Scanning Technology

A technology that uses a laser to scan a surface and record its geometry and shape. Used for reverse engineering.

Reverse Engineering

The process of creating a digital model of a physical object by taking measurements and converting them into digital data. This process usually involves detailed measurements.

Additive Manufacturing

A type of manufacturing that adds material layer by layer to create a 3D object.

Direct Digital Manufacturing

Creating physical objects directly from digital files, eliminating the need for traditional tooling and molds.

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Subtractive Manufacturing

A manufacturing process that removes material from a solid block to create a desired shape.

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Hybrid Manufacturing

A combination of additive and subtractive manufacturing processes, often used to leverage the strengths of each method.

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STL File Format

The representation of a 3D object as a series of triangles. Used for sharing 3D information between software programs.

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Conceptualization and CAD

The first step in the Generalized AM Process Chain, involving the creation and development of a 3D design.

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Conversion to STL

The process of converting a 3D model from a CAD format to an STL format, which is specifically used in additive manufacturing.

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Post-processing

The process of preparing a part for its final use after it has been built using additive manufacturing.

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Powder-based Systems

A system that utilizes powder material to build 3D objects. It is a common additive manufacturing technology.

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Photopolymer-based Systems

A type of AM system where a liquid resin is cured using light, typically from an ultraviolet (UV) laser.

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Energy Density

A parameter in additive manufacturing that describes the energy concentration delivered to the material being processed.

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Liquid-phase Sintering

A process used in powder-based systems to fuse powder particles together, often involving partial melting.

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Powder Bed Fusion (PBF)

A category of additive manufacturing processes that use a powder bed and a heat source, such as lasers, to fuse the powder into a solid object.

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Chemically-induced Sintering

The process of fusing powder particles through chemical reactions, often requiring high temperatures.

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Full Melting

A process that completely melts all powder constituents, creating a solid object with a high degree of density.

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Selective Laser Sintering (SLS)

A process that involves selectively melting a powder bed using a laser to create a 3D object. It is one of the oldest commercialized forms of PBF.

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Laser Sintering (LS)

The process of using lasers to fuse powdered materials together, commonly used for creating plastic prototypes.

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Electron Beam Melting (EBM)

A process that uses an electron beam to melt and fuse metal powder particles together, allowing for the creation of metal objects.

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Thermal Activation

A process that applies heat to a material uniformly which often increases the rate of chemical reactions.

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Rate Constant

The rate at which a chemical reaction proceeds.

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Activation Energy

The minimum energy required for a chemical reaction to occur. A lower activation energy means the reaction will happen more easily.

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Thermoset Polymer

A material that is able to withstand repeated cycles of heating and cooling without degrading significantly.

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Thermoplastic Polymer

A material that can be repeatedly softened and hardened by heating and cooling.

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Extrusion-based Systems

A process that involves heating and extruding a material through a nozzle to create a 3D object. It is a common additive manufacturing method.

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Bioextrusion

A type of extrusion process that specializes in materials suitable for biological applications, such as creating medical scaffolds.

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Fused Deposition Modeling (FDM)

A common extrusion-based additive manufacturing process that builds objects by depositing melted plastic filament onto a platform, building layer by layer.

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Solidification

The process of forming a solid, rigid object from a liquid or semi-solid material in additive manufacturing.

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Positional Control

The process of controlling the movement of the extruder during the printing process, ensuring accuracy and precision in the final object.

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Scaffold Architectures

Structures designed to support the growth of cells, commonly used in bioprinting and medical applications.

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Study Notes

Chapter 3&4

  • Laser scanning technology is used for reverse engineering data.
  • Architectural modeling designs may not precisely depict the final product, including textures, colors, and shapes.
  • Color and multiple material systems are becoming more common in additive manufacturing processes.
  • Standardized software processes are needed for direct digital manufacturing.

Manufacturing Processes

  • Additive manufacturing builds material layer by layer.
  • Direct digital manufacturing creates physical products from digital files, directly.
  • Subtractive manufacturing removes material from a solid block.
  • Hybrid manufacturing combines additive and subtractive processes.

Generalized AM Process Chain

  • The first step in the Generalized AM Process Chain is conceptualization and CAD.
  • The STL format describes the geometric surface of a CAD model, not its color or texture.
  • Medical modeling sometimes does not use conventional CAD.

AM Machine Characteristics

  • Solid sheets extrude heated materials to create objects.
  • Powder-based systems utilize powdered materials for printing.
  • Molten material systems extrude heated materials, which are cut and bonded.
  • Photopolymer-based systems use liquid resin cured by light.

General Information

  • Energy density is a factor in metal additive manufacturing.
  • Part orientation and support removal are design considerations for additive manufacturing.
  • Verifying the part is correct before building is crucial.
  • Some AM machines require different setup parameters for different materials. .
  • Shrinkage or coating allowances may be necessary for some parts before they are built.
  • The first few stages of building are often semi-automated.
  • All AM machines should alert the user when the build is complete or when there is no material remaining.
  • STL files are used when converting a CAD model.
  • Material exposure considerations include moisture and light resistance for laser technology.

Other Information

  • The cleanup stage is considered initial in additive manufacturing post-processing.
  • Some post-processing tasks can benefit from tools like power tools (abrasive finishing etc).
  • Post-processing requires manual stages of finishing parts.
  • Voids or bubbles trapped inside parts can cause failure under mechanical stress.
  • Solid sheets used in lamination methods may not need support structures, focusing instead on material management.
  • Paper-based systems sometimes experience handling problems
  • Part orientation, support removal, and part hollowing are additive manufacturing concerns
  • Additive manufacturing parts may not behave according to standard material specifications.
  • Manual skill is required for support removal stages
  • Thicker layers in additive manufacturing don't necessarily lead to more precise parts.
  • Different materials can affect the time and resources required in additive manufacturing processes
  • Stereolithography is a type of vat photopolymerization process.
  • Photopolymerization reaction rates depend on light and exposure time.
  • Various photopolymerization configurations have unique characteristics.
  • UV protection is important for newer resins in photopolymer-based systems.
  • Visible light is commonly used in dentistry.
  • Laser beams in vector scan approaches are typical.
  • Some specific types of radiation (like UV, visible light) are used for curing photopolymers.
  • Photopolymers are often used in photoresists.

Powder Bed Fusion (PBF)

  • Selective Laser Sintering (SLS) was the first commercialized PBF process.
  • PBF processes can use a variety of materials, not just metal.
  • The process may include Liquid-phase sintering, which involves partial melting.
  • Other PBF mechanisms include solid-state sintering, chemically induced sintering, & full melting, depending on the chosen material.
  • The powder particle size influences the accuracy and surface finish of the produced parts.
  • Powder Bed Fusion has an advantage over other additive manufacturing processes because it allows processing a variety of materials.
  • Total part construction time might be longer due to the preheating and cooling cycles in PBF.
  • Some parameters, such as powder particle size, influence the final microstructure of the produced parts.
  • Certain materials, like cobalt-chromium, are suitable for PBF processing.
  • Full melting in PBF refers to complete melting of the material.
  • Titanium and stainless steel are common alloys in PBF processes.
  • Electron beams are used in some processes, like Electron Beam Melting (EBM).
  • Laser scanning mechanisms may necessitate a vacuum environment.
  • The powdered material can be degraded with incorrect chamber gas/atmosphere control.
  • Various materials and components support the different approaches in PBF.

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