Additive Manufacturing Process Chain

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Questions and Answers

What is the primary purpose of converting a CAD model to STL format?

To export as a 3D printing file

To create a detailed engineering drawing

To enhance the visual quality of the model

To simplify the model's geometry for AM (correct)

The conversion to STL format is a manual process requiring significant user intervention.

False

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

Medical modeling

The eight steps in the Additive Manufacturing process include conceptualization and CAD, conversion to STL, transfer and manipulation of STL file, ________, build, part removal and cleanup, post-processing of part, and application.

machine setup Signup and view all the answers

Match the type of additive manufacturing system with its description:

Photopolymer based systems = Use light to cure liquid resin Powder-based systems = Utilize powdered materials that are fused together Molten material systems = Extrude melted materials layer by layer Solid sheets = Adhere layers of sheet materials together Signup and view all the answers

What are common considerations in the design for additive manufacturing?

Part orientation and removal of supports Signup and view all the answers

Energy density is an important factor in metal additive manufacturing systems.

True Signup and view all the answers

What is one of the initial actions required prior to building a part?

Use the visualization tool Signup and view all the answers

What is the significance of part removal and cleanup in the additive manufacturing process?

Ensures the final product is ready for use and free of excess material. Signup and view all the answers

All AM machines must run a variety of materials with numerous setup parameters.

False Signup and view all the answers

What is the purpose of repositioning the part before building?

To allow it to be built at a specific location within the machine. Signup and view all the answers

Parts may require _____ or coating allowances.

shrinkage Signup and view all the answers

Match the following actions with their related descriptions:

Verify the part = Ensure accuracy before building Segmentation of STL files = Divide parts for easier handling Machine setup = Configure parameters for operation Manual finishing = Prepare parts for final use Signup and view all the answers

During which phase does the process switch to computer-controlled building?

Layer-based manufacturing phase Signup and view all the answers

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

True Signup and view all the answers

What does significant manual finishing typically entail for parts produced by AM machines?

It involves cleaning and preparing parts for ready-to-use condition. Signup and view all the answers

What is the role of support structures in additive manufacturing?

To stabilize the part during the building process Signup and view all the answers

Post-processing tasks always require the use of power tools.

False Signup and view all the answers

What are some common post-processing techniques used in additive manufacturing?

Abrasive finishing, polishing, sandpapering, and application of coatings. Signup and view all the answers

AM materials often have small ______________ trapped inside them, leading to potential failure under stress.

voids Signup and view all the answers

What is a potential consequence of poor technique in support removal?

Low quality output of the part Signup and view all the answers

Match the additive manufacturing issues with their descriptions:

Anisotropic properties = Different properties in different directions Material degradation = Material not bonding or crystallizing optimally Support removal = Often requires manual skill to avoid damaging parts Application specificity = Varies by the requirements of the final product Signup and view all the answers

Many applications using AM processes do not require high performance from their __________.

components Signup and view all the answers

Why may parts produced by additive manufacturing behave differently than those made by conventional methods?

They may have voids, anisotropic properties, or material degradation. Signup and view all the answers

What is the nominal layer thickness range for most SL technology machines?

0.05 - 0.1 mm Signup and view all the answers

Thicker layers in additive manufacturing (AM) lead to parts being built more precisely.

False Signup and view all the answers

What material property must be considered during post-processing that involves heat?

Heat resistance or melting temperature Signup and view all the answers

In powder-based systems, there is no need to use __________.

supports Signup and view all the answers

Match the following AM technologies with their characteristics.

Photopolymer-Based Systems = Requires support from the same material used for the part Powder-Based Systems = Deposits a bed of powder layer-by-layer Droplet Deposition = Possible to modify the support material as it prints Binder Printing = Parts can be colored using colored binder material Signup and view all the answers

What is an advantage of photopolymer-based systems?

Good accuracy with thin layers Signup and view all the answers

Newer resins in photopolymer systems offer improved temperature resistance and strength.

True Signup and view all the answers

What type of machine typically has a nominal layer thickness of 0.254 mm?

FDM Dimension machines Signup and view all the answers

What is a key requirement for molten material systems that melt and deposit materials in a molten state?

Support structures Signup and view all the answers

Extrusion processes like FDM always generate supports automatically.

False Signup and view all the answers

What is one of the challenges faced when cleaning parts produced by lamination methods?

The laborious process of waste material removal. Signup and view all the answers

Exposure to _____ and excessive light should be avoided in material handling.

moisture Signup and view all the answers

Match the following application areas with their respective technology:

Computerized Tomography (CT) = Medical modeling Magnetic Resonance Imaging (MRI) = Medical modeling 3D ultrasound = Medical modeling FDM = Additive Manufacturing Signup and view all the answers

Which of the following is NOT a factor to consider in metal systems?

Color of the material Signup and view all the answers

List two design considerations for additive manufacturing.

Part orientation, Removal of supports Signup and view all the answers

Some machines in additive manufacturing must be kept away from _____ environments.

dirty or noisy Signup and view all the answers

Which of the following is a type of Vat Photopolymerization process?

Stereolithography Signup and view all the answers

Two-Photon Vat Photopolymerization offers only advantages and no drawbacks.

False Signup and view all the answers

What is one of the key components of photopolymer chemistry?

Photo initiator system Signup and view all the answers

The process that models irradiance and exposure in Vat Photopolymerization is known as __________.

Photopolymerization Process Modeling Signup and view all the answers

Match the following scan patterns with their descriptions:

WEAVE = A pattern that helps in smooth layering STAR-WEAVE = A complex pattern designed for intricate builds ACES = An advanced vector scan pattern for enhanced accuracy Layer-based build phenomena = Patterns related to the construction of layers in photopolymerization Signup and view all the answers

Which of the following radiation types is primarily used to cure commercial photopolymers?

UV light Signup and view all the answers

Epoxy and vinylether are examples of free radical polymerization.

False Signup and view all the answers

What is the role of a photoinitiator in photopolymerization?

To convert physical energy of light into chemical energy in the form of reactive intermediates. Signup and view all the answers

Photopolymer resins must be cleaned, post-cured, and ________ after building.

finished Signup and view all the answers

Match the following photopolymerization processes with their respective characteristics:

Free radical polymerization = Acrylate-based Cationic polymerization = Epoxy and vinylether Resin formulation = Uses multifunctional monomers Interpenetrating polymer networks = Acrylates and epoxides form networks Signup and view all the answers

What component of the laser scan VP machines is responsible for liquid resin application?

Recoating system Signup and view all the answers

Both di-functional and higher functionality monomers are commonly used in SL resins.

True Signup and view all the answers

Name two main subsystems of vector scan VP machines.

Laser and optics systems, control system. Signup and view all the answers

Which approach in photopolymerization does not require recoating of the resin layer?

Two-photon approach Signup and view all the answers

In the microelectronic industry, visible light is predominantly used for photomask materials.

False Signup and view all the answers

What device is used to pattern the large radiation beam in the mask projection approach?

Digital Micromirror Device Signup and view all the answers

In photopolymerization processes, the ___ scan approach is typical of commercial SL machines.

vector Signup and view all the answers

Match the photopolymerization approaches with their descriptions:

Vector scan = Scanning laser beams needed Mask projection = Entire layers irradiated at once Two-photon = High resolution point-by-point Layer-wise = Successive layer applications Signup and view all the answers

What type of light is primarily used in photopolymerization processes?

Ultraviolet (UV) Signup and view all the answers

Charles Hull discovered solid polymer patterns by exposing UV curable materials to a scanning laser.

True Signup and view all the answers

What is one common application of photo-curable resins in dentistry?

Sealing the top surfaces of teeth to prevent cavities Signup and view all the answers

The mid 1980s marked the beginning of SL technology due to Charles Hull's experiments with _____ curable materials.

UV Signup and view all the answers

Match the following radiation types with their uses in curing commercial photopolymers:

Gamma rays = Used in various curing applications X-rays = Used in treating medical materials Ultraviolet rays = Primarily used in photopolymerization processes Visible light = Alternative curing method Signup and view all the answers

What is a significant drawback of vat photopolymerization technology?

Limited chemistries for photopolymers Signup and view all the answers

The surface finish of SL parts can range from submicron to over 100 um Ra depending on the orientation of the surfaces.

True Signup and view all the answers

What is the maximum size of fabrication structure achievable with the specified microsterolithography process?

10 mm x 10 mm x 10 mm Signup and view all the answers

The minimum size of a hardened polymer unit in the microsterolithography process is ___ in the x and y directions.

5 µm x 5 µm Signup and view all the answers

Match the advantages of vat photopolymerization technology with their descriptions:

Accuracy = 0.002 in/in Surface finish = Varies based on surface orientation Flexibility = Supports different configurations Speed = Fast production compared to laser scanning Signup and view all the answers

Which of the following statements about mask projection VP technologies is true?

They are faster compared to laser scan SL technologies. Signup and view all the answers

Photopolymers used in additive manufacturing are known for their exceptional impact strength and durability.

False Signup and view all the answers

What is the position accuracy achieved in the x-y directions during the microsterolithography process?

0.25 µm Signup and view all the answers

Study Notes

Converting CAD Models to STL Format

Converting a CAD model to STL format is essential for additive manufacturing processes.
The STL format represents a 3D object as a mesh of triangular facets, making it suitable for additive manufacturing machines.
The conversion process can be manual, requiring user intervention, or automated using dedicated software tools.

Applications of Additive Manufacturing

Additive manufacturing, also known as 3D printing, offers various applications beyond conventional CAD modeling.
One example is bioprinting, where living cells and biomaterials are used to create 3D structures for tissue engineering and drug discovery.

Additive Manufacturing Process Steps

The eight key steps in an additive manufacturing process:
- Conceptualization and CAD design
- Conversion to STL format
- Transfer and manipulation of STL file
- Slicing and path generation (essential for machine control)
- Build process
- Part removal and cleanup
- Post-processing of the part
- Application of the manufactured part

Additive Manufacturing System Types

Fused Deposition Modeling (FDM): Uses a thermoplastic filament that is extruded layer by layer to build the part.
Stereolithography (SLA): Employs a vat of photopolymer resin that is selectively cured by a UV laser beam, layer by layer, to create the 3D object.
Selective Laser Sintering (SLS): Involves a powder bed of thermoplastic material that is selectively sintered by a laser, layer by layer, to form the object.
Electron Beam Melting (EBM): Uses an electron beam to melt and fuse metallic powder into a solid part, layer by layer.

Design Considerations for Additive Manufacturing

Design for manufacturability: Parts should be designed with consideration for overhangs, support structures, and ease of removal.
Material selection: Various materials, including thermoplastics, photopolymers, metals, and ceramics, are available for additive manufacturing.
Energy density: This factor is crucial for metal additive manufacturing systems, as it influences the melting and consolidation of the metal powder.

Initial Actions in Additive Manufacturing

One of the essential initial actions is part orientation before building, determining the build direction and support structure requirements.

Significance of Part Removal and Cleanup

Part removal and cleanup are important steps in additive manufacturing to remove support structures and excess material generated during the build process.
This ensures a clean and finished product ready for post-processing.

Repositioning the Part in Additive Manufacturing

Repositioning or relocation of the part during the build process is crucial for larger or complex parts.
This allows for a smooth transition between layers and ensures accurate geometry.

Allowances in Additive Manufacturing

Parts may require draft angles for easier removal from the build platform and prevent material sticking.
Coating allowances can be incorporated to accommodate post-processing treatments like painting or surface finishing.

Additive Manufacturing Process Phases

The phase where the process switches from manual to computer-controlled building is slicing and path generation.
During this step, the STL file is sliced into thin horizontal layers, and toolpaths are generated for the machine to follow.

Machine Alerts and Completion

Additive manufacturing machines typically alert the user via visual or auditory cues when the build is complete or when material is depleted.

Manual Finishing for Additive Manufacturing Parts

Significant manual finishing for AM parts usually involves removing support structures, smoothing surfaces, and improving surface quality.

Role of Support Structures

Support structures are essential in additive manufacturing to prevent overhangs and unsupported features from sagging or collapsing during the build process.
They are removed after building to reveal the final part.

Post-processing Techniques in Additive Manufacturing

Post-processing techniques include sanding, polishing, machining, heat treating, and cleaning to improve surface finish, dimensional accuracy, and material properties.

Material Properties in Additive Manufacturing

Common AM materials often contain tiny voids or pores trapped inside, potentially leading to weakness and failure under stress.

Consequences of Poor Support Removal Technique

Insufficient or improper support removal can result in damage to the part, incomplete removal of support structures, and compromised aesthetics.

Considerations for AM Parts

Many applications using AM do not require high performance from their components.
AM parts may exhibit different mechanical properties compared to conventionally manufactured parts due to anisotropic material properties and different internal microstructure.

Layer Thickness in Additive Manufacturing

The nominal layer thickness range for most SL technology machines is 0.05 to 0.25 mm.
Thicker layers in AM can result in decreased surface finish and dimensional accuracy.

Material Properties and Post-processing

The material property that needs consideration during post-processing involving heat is thermal stability.
Some materials can distort or degrade when exposed to high temperatures.

Powder-based Systems in Additive Manufacturing

In powder-based systems like SLS, there is no need to use support structures as the powder itself provides support for overhanging features.

Additive Manufacturing Technologies and Characteristics

Fused Deposition Modeling (FDM): Uses thermoplastic filament, relatively low cost, good for prototyping.
Stereolithography (SLA): Uses photopolymer resin, excellent surface finish, suitable for functional parts.
Selective Laser Sintering (SLS): Uses powder bed of thermoplastic material, strong and durable parts, good for complex designs.
Electron Beam Melting (EBM): Uses metallic powder, high-strength metal parts, suitable for aerospace and medical applications.

Photopolymer-based Systems

Photopolymer-based systems offer several advantages, including high resolution, precise dimensional accuracy, and a variety of materials.
Newer resins in these systems have improved temperature resistance and strength.

Layer Thickness in Molten Material Systems

Machines using molten material systems typically have a nominal layer thickness of 0.254 mm (0.01 inch).

Requirement for Molten Material Systems

A key requirement for molten material systems is a reliable melt-extrusion system that consistently melts and deposits materials in a molten state.

Challenges in Lamination Methods

One challenge faced when cleaning parts produced by lamination methods is removing excess material and achieving a smooth surface finish.

Material Handling Precautions

Exposure to humidity, excessive light, and ultraviolet radiation should be avoided in materials handling to prevent degradation and maintain material quality.

Application Areas and Technology

Biomedical applications: SLA, SLS, EBM.
Dental prosthetics: SLA.
Automotive prototyping: FDM, SLA.
Aerospace parts: SLS, EBM.
Jewelry and art: SLA, SLS.

Design Considerations for Metal Systems

Surface roughness: Metals typically require specific surface finishes for functionality and aesthetics.
Thermal conductivity: Metal parts can quickly heat up during the build process and may require special considerations to mitigate heat-induced stresses.
Melting point: The melting point of the metal is a critical factor in determining the appropriate laser power and build parameters.

Design Considerations for Additive Manufacturing

Design for manufacturability: Parts should be designed to minimize overhangs and ensure easy removal from the build platform.
Material selection: Choose appropriate materials that meet specific requirements in terms of mechanical properties, thermal stability, and chemical resistance.

Environment Considerations for AM Machines

Some machines in additive manufacturing must be kept away from humid environments to avoid corrosion and ensure proper material handling.

Vat Photopolymerization Processes

One type of Vat Photopolymerization process is Stereolithography (SLA).

Two-Photon Vat Photopolymerization

While Two-Photon Vat Photopolymerization (TPP) offers potential for high resolution and intricate structures, it also poses challenges like limited build volume, complex equipment setup, and slower build speeds.

Photopolymer Chemistry

A key component of photopolymer chemistry is photoinitiators: light-sensitive molecules that initiate the polymerization reaction when exposed to specific wavelengths of light.

Modeling Irradiance and Exposure

The process that models irradiance and exposure in Vat Photopolymerization is known as digital light processing (DLP).

Scan Patterns in Vat Photopolymerization

Raster Scan: The radiation source scans in a series of parallel lines, similar to a TV screen, creating a 2D pattern on the resin surface.
Vector Scan: The radiation source scans in a continuous, uninterrupted path, following a predefined vector, ensuring a smooth and continuous curing process.
Spiral Scan: The radiation source follows a spiral pattern, allowing for efficient and consistent curing of the resin layer.

Radiation Type for Photopolymers

Ultraviolet (UV) radiation is primarily used to cure commercial photopolymers due to its effectiveness in initiating the polymerization reaction.

Free Radical Polymerization

Epoxy and vinylether are examples of commonly used monomers in photopolymer resins.

Role of Photoinitiator

Photoinitiators in photopolymerization absorb light energy and initiate polymerization. They create free radicals that initiate the chain reaction, causing monomers to bond together and create a solid polymer.

Post-processing for Photopolymer Resins

Photopolymer resins must be cleaned, post-cured, and supported after building to enhance their properties and ensure proper functionality.

Photopolymerization Processes and Characteristics

Stereolithography (SLA): Uses a vat of photopolymer resin that is selectively cured by a UV laser beam, layer by layer, to create the 3D object.
Digital Light Processing (DLP): Uses a digital projector to project an image onto the resin surface, selectively curing the resin layer by layer.
Two-Photon Polymerization (TPP): Uses a femtosecond laser to selectively cure resin in a two-photon absorption process, enabling high resolution and complex structures.

Components of Laser Scan VP Machines

Liquid resin application system: This component is responsible for accurately dispensing and spreading the liquid resin onto the build platform.

Subsystems of Vector Scan VP Machines

Radiation source: Emits the specific wavelength of light required to activate the photopolymerization process.
Scanning system: Controls the movement and orientation of the radiation source, ensuring precise control of the curing pattern.

Approaches in Photopolymerization

Mask Projection: A mask pattern is projected onto the resin surface using a high-intensity light source, simultaneously curing the entire exposed area.
Scanning: A laser beam is used to selectively cure the resin layer by layer, following a defined scan path.

Microelectronic Industry and Visible Light

In the microelectronic industry, visible light is predominantly used for photomask materials because it offers adequate resolution for microchip fabrication.

Device for Patterning Radiation Beam

A spatial light modulator (SLM) is used to pattern the large radiation beam in the mask projection approach.

Scan Approach in Commercial SL Machines

The raster scan approach is typical of commercial SL machines due to its efficiency and ease of implementation.

Photopolymerization Approaches and Descriptions

Mask projection: A mask pattern is projected onto the resin surface, curing the entire exposed area.
Scanning: A laser beam selectively cures the resin layer by layer, following a defined scan path.

Light Type for Photopolymerization

Ultraviolet (UV) light is primarily used in photopolymerization processes to cure commercial photopolymers.

Charles Hull's Discovery

Charles Hull discovered solid polymer patterns by exposing UV curable materials to a scanning laser, marking the beginning of SL technology.

Application of Photo-curable Resins in Dentistry

One common application of photo-curable resins in dentistry is fabrication of dental crowns, bridges, and dentures.

Charles Hull's Experiments

The mid 1980s marked the beginning of SL technology due to Charles Hull's experiments with UV curable materials

Radiation Types for Curing Photopolymers

Ultraviolet (UV) radiation: Most commonly used for curing photopolymers in commercial SL machines.
Visible light: Used in some specialized photopolymerization processes, particularly in microelectronics.
Electron beam: A less common method, but potentially useful for high-throughput applications.

Drawback of Vat Photopolymerization Technology

A significant drawback of vat photopolymerization technology is the need for post-processing to remove support structures and achieve a smooth surface finish.

Surface Finish of SL Parts

The surface finish of SL parts can range from submicron to over 100 um Ra depending on factors like the orientation of surfaces, layer thickness, and post-processing methods.
Smaller layer thicknesses generally result in smoother surface finishes.

Fabrication Structure Size in Microsterolithography

The maximum size of a fabrication structure achievable with the specified microsterolithography process is 200 mm x 200 mm x 50 mm.

Harden Polymer Unit Size in Microsterolithography

The minimum size of a hardened polymer unit in the microsterolithography process is 100 nm in the x and y directions.

Advantages of Vat Photopolymerization Technology

High resolution: Offers detailed features and intricate designs due to the precise laser control.
Variety of materials: Supports a wide range of photopolymer resins with varying mechanical properties and optical characteristics.
Fast build speed: Can produce parts relatively quickly compared to other AM processes.
Excellent surface finish: Provides a smooth and detailed surface finish, often requiring less post-processing.

True Statement About Mask Projection VP Technologies

Mask projection VP technologies offer high-throughput, simultaneous curing of the entire resin layer, and are suitable for large-scale production.

Position Accuracy in Microsterolithography

The position accuracy achieved in the x-y directions during the microsterolithography process is 10 nm.

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Description

Explore the key steps involved in the additive manufacturing process chain, from conceptualization and CAD modeling to post-processing and application. This quiz covers various types of AM systems and the specific considerations involved in metal and polymer production. Test your knowledge on machine setup, material handling, and the importance of equipment maintenance.