Additive Manufacturing Processes Overview
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What is the first step in the Generalized Additive Manufacturing Process Chain?

  • Conceptualization and CAD (correct)
  • Build
  • Post-processing of part
  • Machine setup

    • STL stands for Stereolithography.

    True

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

    Medical modeling

    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 different AM systems with their characteristics:

    <p>Photopolymer based systems = Use light to cure resin Powder-based systems = Utilize powdered material to build parts Molten material systems = Extrude melted material to create objects Solid sheets = Build layers from solid sheets of material</p> Signup and view all the answers

    Which of the following is NOT a step in the AM process chain?

    <p>Material quality assessment</p> Signup and view all the answers

    Additive Manufacturing is only applicable to metal systems.

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

    What is a key consideration in Design for AM when creating a part?

    <p>Part orientation</p> Signup and view all the answers

    Which process automatically generates supports for molten material systems?

    <p>Thermojet process</p> Signup and view all the answers

    Solid sheets used in lamination methods require supports for their production.

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

    What should be avoided when using material handling systems in additive manufacturing?

    <p>Moisture and excess light</p> Signup and view all the answers

    In additive manufacturing design, features that prevent parts from being easily removed are called __________ features.

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

    Match the application areas with their respective imaging techniques:

    <p>Medical modeling = 3D ultrasound Metal systems = Subtractive manufacturing</p> Signup and view all the answers

    What is one of the key considerations when working with metal systems?

    <p>Maintenance of equipment</p> Signup and view all the answers

    What is a laborious process required after using lamination methods?

    <p>Cleaning up the parts</p> Signup and view all the answers

    In the extrusion process, supports must always be generated automatically.

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

    What is a possible issue that can arise from poor technique in support removal during additive manufacturing?

    <p>Low product quality</p> Signup and view all the answers

    Post-processing is exclusively done using manual techniques.

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

    What is the term used to describe the part that should be separated from the build platform in additive manufacturing?

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

    Some additive manufacturing machines require __________ to prevent parts from collapsing during the building process.

    <p>support structures</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Post-processing = Manual finishing of parts for application purposes Anisotropic properties = Different properties in different directions Support structures = Stabilization during building Additive manufacturing (AM) = Process of creating objects layer by layer</p> Signup and view all the answers

    What characteristic do AM parts often exhibit due to the manufacturing process?

    <p>Trapped voids or bubbles</p> Signup and view all the answers

    The properties of parts created through additive manufacturing are often isotropic.

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

    Name one advantage of advancements in AM materials and processes.

    <p>Increased number of applications for components</p> Signup and view all the answers

    What is one benefit of reverse engineering data using laser scanning technology?

    <p>Creates architectural models with textures and colors</p> Signup and view all the answers

    The STL file format is effective for all additive manufacturing technologies.

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

    What future trend is expected in additive manufacturing regarding materials?

    <p>Color and multiple material systems becoming more common.</p> Signup and view all the answers

    Additive manufacturing technologies may integrate ______ processing elements as they evolve.

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

    Match the following topics with their corresponding descriptions:

    <p>Direct digital manufacturing = Increases the need for standardized software processes Software optimization = Enhances additive manufacturing processing efficiency Hybrid technologies = Combine additive and subtractive manufacturing methods Post-processing techniques = Refine and enhance printed models after creation</p> Signup and view all the answers

    What is the nominal layer thickness for most FDM Dimension machines?

    <p>0.254 mm</p> Signup and view all the answers

    Thicker layers in additive manufacturing lead to more precise builds.

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

    What common issue do fine details in a design cause for some AM technologies?

    <p>Problems with wall thickness.</p> Signup and view all the answers

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

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

    Match the following AM machine types with their characteristics:

    <p>Photopolymer-Based Systems = Good accuracy with thin layers but poor mechanical properties FDM Machines = Nominal layer thickness of 0.254 mm Powder-Based Systems = No supports needed for builds Zcorp Parts = Can be colored using binder material</p> Signup and view all the answers

    What is a requirement for post-processing that involves heat?

    <p>Knowledge of the melting temperature of the material</p> Signup and view all the answers

    With droplet deposition systems, support material cannot be modified as it comes out of the print head.

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

    What type of systems primarily use a vat of liquid photopolymer?

    <p>Photopolymer-Based Systems</p> Signup and view all the answers

    Which type of radiation is primarily used in photopolymerization processes?

    <p>Ultraviolet (UV) radiation</p> Signup and view all the answers

    Photopolymers were developed in the 1980s.

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

    Who conducted experiments with UV curable materials and contributed to sl technology?

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

    Photo-curable resins are commonly used in __________ to seal dental surfaces.

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

    Match the following types of radiation to their usage in curing photopolymers:

    <p>Gamma rays = Used in medical imaging X-rays = Applications in treatment and inspection Ultraviolet (UV) = Curing photo-curable resins Visible light = Used in some photopolymer systems</p> Signup and view all the answers

    What is one type of technology discussed in vat photopolymerization processes?

    <p>Two-Photon Vat Photopolymerization</p> Signup and view all the answers

    Laser-resin interaction is an important factor in photopolymerization process modeling.

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

    Name one component of the photopolymerization materials used in vat photopolymerization.

    <p>UV curable photopolymers</p> Signup and view all the answers

    In photopolymerization, the formation of a three-dimensional structure occurs through the process of __________.

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

    Match the following scan patterns with their descriptions:

    <p>WEAVE = A scan pattern characterized by back-and-forth motion STAR-WEAVE = A scan pattern that resembles a star shape ACES = A scan pattern designed to reduce build errors Layer-based = A technique focusing on building one layer at a time</p> Signup and view all the answers

    Which photopolymerization approach uses a large patterned radiation beam?

    <p>Mask projection</p> Signup and view all the answers

    In dentistry, UV radiation is predominantly used for photopolymerization.

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

    Name one advantage of the two-photon photopolymerization approach.

    <p>It does not require recoating.</p> Signup and view all the answers

    The ______ approach involves scanning laser beams in photopolymerization.

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

    Match the photopolymerization processes to their primary configurations:

    <p>Vector scan = Point-wise approach Mask projection = Layer-wise approach Two-photon = High resolution point-by-point Visible light = Used predominantly in dentistry</p> Signup and view all the answers

    What is the primary role of photoinitiators in photopolymer materials?

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

    UV curable photopolymers are mainly used in the food packaging industry.

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

    Name one type of polymerization used in photopolymer chemistry.

    <p>Free radical polymerization or Cationic polymerization</p> Signup and view all the answers

    The laser scan vat photopolymerization creates solid parts by selectively solidifying a liquid photopolymer resin using a __________ laser.

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

    Match the following types of radiation used for curing photopolymers with their characteristics:

    <p>Gamma rays = High penetration capabilities X-rays = Used in medical applications UV = Most prevalent in commercial use Electron beams = Effective for surface curing</p> Signup and view all the answers

    Which of the following is NOT a component of the machine subsystem hierarchy in Vector Scan VP machines?

    <p>Cooling system</p> Signup and view all the answers

    Interpenetrating polymer networks are formed primarily by the cationic polymerization of acrylates.

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

    What is the function of the recoater blade in the Vector Scan VP process?

    <p>To deposit a new layer of resin and smooth the surface of the vat</p> Signup and view all the answers

    What is the position accuracy in the x-y directions for the atypical point-wise Microsterolithography process?

    <p>0.25 µm</p> Signup and view all the answers

    Two-photon VAT photopolymerization has no notable speed advantage over laser scan SLA.

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

    What is one main drawback of using photopolymer materials in additive manufacturing?

    <p>Limited impact strength and durability compared to thermoplastics.</p> Signup and view all the answers

    The minimum size of the unit of hardened polymer in atypical Microsterolithography is ______.

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

    Match the following characteristics with their respective advantages or drawbacks in Additive Manufacturing:

    <p>Accuracy = Advantage of SLA-250 Surface finish = Submicron Ra for upfacing surfaces Flexibility = Supports many different configurations Aging of materials = Drawback of photopolymers</p> Signup and view all the answers

    What is the maximum size of the fabrication structure in the atypical Microsterolithography process?

    <p>10 mm x 10 mm x 10 mm</p> Signup and view all the answers

    Surface finishes for slanted angles in SLA can be better than for upfacing surfaces.

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

    What is the spot size of the UV beam in the specifications for atypical point-wise Microsterolithography?

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

    Study Notes

    Generalized AM Process Chain

    • The generalized AM process chain includes eight steps: conceptualization and CAD, conversion to STL, transfer and manipulation of STL file on AM machine, machine setup, build, part removal and cleanup, post-processing of part, and application.
    • There are variations in the AM process depending on the machine, material, and desired application.
    • Photopolymer-based systems are easy to set up, but have poor mechanical properties compared to other AM materials.
    • Powder-based systems do not require supports, while molten material systems do.
    • Solid sheet systems require waste material removal, which can be a laborious process.
    • Metal systems require careful attention to substrate usage, energy density, weight, accuracy, and speed.

    Maintenance of Equipment

    • AM machines may use fragile laser or printer technology, requiring careful monitoring and a clean, low-noise environment.

    Materials Handling Issues

    • Moisture and excess light should be avoided when handling AM materials.
    • Material loading is typically done offline using software systems.
    • Recycling of unused material from builds is sometimes possible.

    Design for AM

    • Consider part orientation, support removal, hollowing out, undercuts, interlocking features, part count reduction, and identification markings when designing parts for AM.

    Application Areas

    • Applications that do not involve conventional CAD modeling include medical modeling (using CT, MRI, and 3D ultrasound), reverse engineering data (using laser scanning technology), and architectural modeling.
    • Future developments in AM include thicker layers, processing regions rather than layers, and more complex processes within a single machine.
    • Color and multi-material systems will become more common in the future.
    • Software is increasingly being optimized for AM processing, including dedicated software for converting designs into printable formats.
    • As direct digital manufacturing becomes more common, standardized software processes based around AM will be needed.

    Vat Photopolymerization Processes

    • Vat Photopolymerization processes are used to cure liquid photopolymers using radiation to create 3D structures.
    • Photopolymers materials are primarily used for coating and printing industries and were developed in 1960.
    • Radiation sources for curing photopolymers include gamma rays, x-rays, electron beams, UV, and visible light.
    • UV and visible light are primarily used for SL systems.

    Photopolymerization Materials

    • UV curable photopolymers are used as photoresists in the microelectronics industry.
    • Photopolymer chemistry includes free radical polymerization (acrylates) and cationic polymerization (epoxies and vinylether).
    • Resin formulations use multifunctional monomers (MFM) along with photoinitiator system, monomer formulation, and interpenetrating polymer network formation.

    Laser Scan Vat Photopolymerization

    • Processes creates solid parts using an UV laser to selectively solidify liquid photopolymer resin.
    • Part building involves creating cross-sectional contours or slices, one on top of another.
    • Post-curing includes cleaning, post-curing, and finishing (removing support structures, sanding, and filing for desired surface finishes).

    Vector Scan VP Machines

    • Five main subsystems: recoating system, platform system, vat system, laser and optics systems, and control system.
    • Process: after a layer is cured, the platform dips down by a layer thickness, then the recoater blade deposits a new layer of resin and smooths the surface of the vat.

    SL Scan Patterns

    • Layer-based build phenomena and errors: discretization causes "stair steps".
    • WEAVE scan pattern: a back-and-forth zigzag pattern reduces staircase artifacts.
    • STAR-WEAVE scan pattern: reduces stair-stepping by alternating the direction of the laser beam.
    • ACES scan pattern: a complex pattern featuring serpentine and star-like patterns that reduces contour errors and increases fabrication efficiency.

    Vector Scan Micro-Vat Photopolymerization

    • Microfabrication applications: using lasers and X-rays as energy sources.
    • Atypical point-wise Microsterolithography process: 5-µm spot size of the UV beam, position accuracy of 0.25 µm in x-y directions and 1 µm in z-direction, minimum size of hardened polymer of 5 µm x 5 µm x 3 µm, maximum size of fabrication structure of 10 mm x 10 mm x 10 mm.

    Mask Projection VP Technologies and Processes

    • Mask Projection VP technology: uses a large radiation beam patterned by a device like a Digital Micromirror Device to irradiate entire layers at one time.

    Two-Photon VP

    • High resolution point-by-point approach: using the intersection of two scanning laser beams.

    Process Benefits and Drawbacks

    • Advantages of vat photopolymerization: accuracy (0.002 in/in for SLA-250), surface finish (ranging from submicron Ra for upfacing surfaces to over 100 um Ra for slanted angles), and flexibility.
    • Drawbacks of vat photopolymerization: limited chemistries (acrylates and epoxies), low impact strength and durability compared to injection molded thermoplastics, material aging resulting in degraded mechanical properties, limitations for production applications.

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    Description

    This quiz explores the generalized additive manufacturing (AM) process chain, covering key steps from conceptualization to application. It also delves into maintenance considerations for AM equipment and material handling issues. Test your knowledge on the nuances and variations of different AM systems.

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