Questions Bank - Chapters 3, 4, 5, & 6 PDF

Chapter 3&4 1. Which technology is utilized for reverse engineering data? A. 3D printing B. Virtual reality C. Computer-aided design D. Laser scanning technology Answer: Laser scanning technology (D) Laser scanning technology is speciﬁcally mentioned as a means for reverse engineering data. 2. Architectural modeling designs only depict the exact productionsof the ﬁnal design. A. True B. False Answer: False (B) Architectural modeling can include modiﬁcations that show textures, colors,and shapes that may not be exact representations of the ﬁnal product. 3. What is becoming more common in additive manufacturingprocesses? Answer: Color and multiple material systems The text notes that the use of color and diﬀerent materials in additivemanufacturing is increasing. 1 4. Standardized software processes are needed as direct digitalmanufacturing becomes more............................... Answer: common The growth of direct digital manufacturing creates a demand for standardizedsoftware processes. 5. Match the following types of manufacturing processes with theirdescriptions: 1. Additive A. Building up material layer by layer manufacturing 2. Direct digital B. Creating physical products directly manufacturing from digital ﬁles 3. Subtractive C. Combination of additive and manufacturing subtractive processes 4. Hybrid D. Removing material from a solid manufacturing block Answer: Additive manufacturing = Building up material layer by layer Subtractive manufacturing = Removing material from a solid block Hybrid manufacturing = Combination of additive and subtractive processes Direct digital manufacturing = Creating physical products directly from digital ﬁles 2 6. What is the ﬁrst step in the Generalized AM Process Chain? A. Conceptualization and CAD B. Conversion to STL C. Post-processing of part D. Machine setup Answer: Conceptualization and CAD (A) The ﬁrst step is to conceptualize the design and create a CAD model. 7. The STL format describes the CAD model in terms of color andtexture. A. True B. False Answer: False (B) STL describes the geometric surface of the model, not its color or texture. 8. Name one application area of additive manufacturing that doesnot involve conventional CAD modeling. Answer: Medical modeling Medical modeling is one area where traditional CAD is not typically used. 9. The process of converting a CAD model to STL involvesapproximating the surface of the model with a series of................................................... Answer: triangular facets STL uses triangular facets to represent the geometry of the CAD model. 3 10. Match the following types of AM machines with theircharacteristics: 1. A. Extrude heated materials to create Solid objects sheets 2. B. Utilize powdered materials for Powder- printing based systems 3. C. Layer materials that are cut then Molten bonded material systems D. Use liquid resin cured by light 4. Photopolymer based systems Answer: Photopolymer based systems = Use liquid resin cured by light Powder-based systems = Utilize powdered materials for printing Molten material systems = Extrude heated materials to create objectsSolid sheets = Layer materials that are cut then bonded 11. What type of ﬁle is created from the conversion of a CAD model? A. DXF B. STL C. OBJ D. JPEG Answer: STL (B) An STL ﬁle is created, which is used for additive manufacturing. 4 12. Energy density is a factor to consider in metal additivemanufacturing. A. True B. False Answer: True (A) Energy density plays a critical role in the quality and properties of the printedmetal parts. 13. List two design considerations for additive manufacturing. Answer: Part orientation, Removal of supports These considerations aﬀect the success and eﬃciency of the AM process. 14. What is one action required prior to building the part? A. Start building immediately B. Verify the part is correct C. Reduce part size D. Apply ﬁnal coating to the part Answer: Verify the part is correct (B) Verifying the part is important to ensure it meets the required speciﬁcationsbefore building. 5 15. All AM machines require the same setup parameters regardlessof the material used. A. True B. False Answer: False (B) Diﬀerent AM machines may have speciﬁc setup parameters based on thematerials they are designed to use. 16. What may be necessary for some parts before they are built? Answer: Shrinkage or coating allowances Shrinkage or coating allowances account for material changes during thebuilding process. 17. The ﬁrst few stages of the building process are......................................... Answer: semi-automated Initially, there is considerable manual control, interaction, and decision-makingrequired. 6 18. Match the actions with their descriptions: 1. Build A. Ensures speciﬁcations are met phase B. Layer-based manufacturing 2. process Machine setup 3. C. Adjusting speciﬁc parameters Verify based on material the part is correct D. Preparing the part for ﬁnal use 4. Removal and cleanup Answer: Verify the part is correct = Ensures speciﬁcations are met Machine setup = Adjusting speciﬁc parameters based on materialBuild phase = Layer-based manufacturing process Removal and cleanup = Preparing the part for ﬁnal use 19. What can happen if an incorrect setup procedure is followed? A. No part will be built B. Finishing will be unnecessary C. The part will be built with unacceptable quality D. The machine will shut down Answer: The part will be built with unacceptable quality (C) An incorrect setup may lead to the part being built, but its ﬁnal quality may becompromised. 7 20. All AM machines will alert the user when the build is complete orwhen there is no material remaining. A. True B. False Answer: True (A) AM machines are designed to provide notiﬁcations when they ﬁnish the build orrun out of material. 21. What might some unusual cases require concerning STL ﬁles? Answer: Segmentation of STL ﬁles Segmentation might be necessary to ensure eﬀective building of more complexparts. 22. Which of the following processes automatically generatessupport structures? A. Solid sheets B. Extrusion process C. Lamination methods D. Thermojet process Answer: Thermojet process (D) The Thermojet process is a droplet-based system that automatically generatessupport structures. 8 23. Solid sheets used in lamination methods require supportstructures during processing. A. True B. False Answer: False (B) In lamination methods, there is no need for support structures; waste materialneeds to be managed instead. 24. What is one common issue experienced by paper-basedsystems? Answer: Handling problems Paper-based systems often face challenges with handling due to their materialproperties. 25. Part orientation, removal of supports, and hollowing out partsare all considerations for................................................... Answer: Additive Manufacturing (AM) These considerations are crucial for optimizing designs in AdditiveManufacturing. 9 26. Match the following issues with their relevant considerations: 1. Material A. Fragility and monitoring exposure 2. B. Oﬄine loading using software Recycling material C. Moisture and light 3. Laser technology D. Clean environments 4. Equipment maintenance Answer: Laser technology = Fragility and monitoring Material exposure = Moisture and light Equipment maintenance = Clean environments Recycling material = Oﬄine loading using software 27. Which of the following factors is NOT a concern for metalsystems compared to polymer systems? A. Energy density B. Speed C. Support structure D. Weight Answer: Support structure (C) Both metal and polymer systems share concerns about support structures andprocessing. 10 28. Interlocking features are considered an advanced designelement in conventional CAD modeling. A. True B. False Answer: False (B) Interlocking features are part of design considerations speciﬁcally for AdditiveManufacturing, not conventional CAD modeling. 29. Name one application area for medical modeling that does notinvolve conventional CAD. Answer: CT or MRI Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) areexamples of medical modeling applications. 30. Why do some additive manufacturing machines require supportstructures? A. To provide additional material for ﬁnishing B. To increase the speed of production C. To prevent parts from collapsing or warping D. To enhance the cooling process Answer: To prevent parts from collapsing or warping (C) Support structures are necessary to maintain the integrity of the part during thebuilding process. 11 31. Post-processing is an automatic stage that requires no manualeﬀort. A. True B. False Answer: False (B) Post-processing usually involves manual stages of ﬁnishing the parts. 32. What may happen to parts created through additivemanufacturing under mechanical stress? Answer: They may fail due to small voids or bubbles trapped inside them. These voids can compromise the structural integrity of the parts. 33. In additive manufacturing, the initial part of the.................................................. stage is the cleanup stage. Answer: post-processing The cleanup stage is considered as the initial part of post-processing in additivemanufacturing. 12 34. Match the terms related to additive manufacturing with theirdeﬁnitions: A. An empty space within the 1. material that can cause structural Void weakness 2. Support B. The stage involving ﬁnishing and structures reﬁning parts after production 3. Post- C. Material properties that vary in processing diﬀerent directions 4. D. Temporary frameworks that Anisotropic prevent part warping during production Answer: Void = An empty space within the material that can cause structural weakness Post-processing = The stage involving ﬁnishing and reﬁning parts afterproduction Anisotropic = Material properties that vary in diﬀerent directions Support structures = Temporary frameworks that prevent part warpingduring production 35. What is the nominal layer thickness for most FDM Dimensionmachines? A. 0.05 mm B. 0.1 mm C. 0.254 mm D. 0.1 mm to 0.2 mm Answer: 0.254 mm (C) The nominal layer thickness for most FDM Dimension machines is typically 0.254 mm. 13 36. What is a potential downside of parts made via additivemanufacturing compared to traditional methods? A. They are always heavier than traditionally manufactured parts B. They lack design ﬂexibility C. They are more expensive to produce D. They may not behave according to standard material speciﬁcations Answer: They may not behave according to standard materialspeciﬁcations (D) Additive manufacturing parts may not behave according to standard materialspeciﬁcations due to inherent production characteristics. 37. Manual skill is unnecessary for the support removal stage inadditive manufacturing. A. True B. False Answer: False (B) A degree of manual skill is required in the support removal stage to avoid mishandling and achieve quality. 38. Thicker layers in additive manufacturing lead to more preciseparts. A. True B. False Answer: False (B) Thicker layers result in quicker builds but are less precise compared to thinnerlayers. 14 39. What are some post-processing tasks that can beneﬁt from theuse of power tools? Answer: Abrasive ﬁnishing, polishing, or application of coatings. Power tools can enhance eﬃciency and quality during post-processing tasks. 40. What must be considered during post-processing that involvesheat in additive manufacturing? Answer: Heat resistance or melting temperature of the material. Understanding the material properties is essential for eﬀective post-processing. 41. In powder-based systems, a bed of powder is deposited................................................... Answer: layer-by-layer Powder-based systems deposit material layer-by-layer, eliminating the need forsupports. 15 42. Match the following types of additive manufacturing systemswith their characteristics: 1. Binder A. No need to use supports Printing B. Use support from the same 2. material as the part Photopolymer- Based Systems C. Has a nominal layer thickness of 3. FDM 0.254 mm Dimension D. Can create colored parts 4. Powder- Based Systems Answer: Photopolymer-Based Systems = Use support from the same material as thepart Powder-Based Systems = No need to use supports Binder Printing = Can create colored parts FDM Dimension = Has a nominal layer thickness of 0.254 mm 43. What is a disadvantage of photopolymer-based systems? A. High mechanical properties B. Diﬃcult to set up C. Good accuracy with thin layers D. Poor mechanical properties compared to others Answer: Poor mechanical properties compared to others (D) Photopolymer systems generally exhibit poor mechanical properties comparedto other additive manufacturing materials. 16 44. Newer resins in photopolymer-based systems degrade rapidlywithout proper UV protection. A. True B. False Answer: True (A) Newer resins can show rapid degradation if UV protective coatings are notapplied. 45. What material processing category can aﬀect the time andresources required in additive manufacturing? Answer: Use of diﬀerent materials. Diﬀerent materials can impact the required skills and resources during themanufacturing process. 46. Which of the following is NOT a process discussed in vat photopolymerization? A. Mask Projection VP technologies B. Stereolithography C. Two-Photon Vat Photopolymerization D. Laser Scan Vat Photopolymerization Answer: Stereolithography (B) Stereolithography is a broader term that encompasses various vat photopolymerization processes. 17 47. Photopolymerization reaction rates are independent of theirradiance and exposure time. A. True B. False Answer: False (B) Photopolymerization reaction rates are actually inﬂuenced by factors likeirradiance and exposure time. 48. What is the purpose of using photo initiators in photopolymerization? Answer: To initiate the polymerization reaction upon exposure to light. Photo initiators are essential for starting the curing process in photopolymers. 49. The..................................................................pattern is one of the scan patterns used in vector scan VP machines. Answer: WEAVE The WEAVE pattern helps in optimizing build speed and accuracy during theprinting process. 18 50. Match the following components with their functions in vat photopolymerization: 1. Laser- resin A. Enhanced mechanical properties interaction B. Building the polymer structure 2. Monomer formulations C. Rate of reaction based on 3. exposure Interpenetrating polymer network D. Curing the resin with laser 4. Photospeed Answer: Monomer formulations = Building the polymer structurePhotospeed = Rate of reaction based on exposure Laser-resin interaction = Curing the resin with laser Interpenetrating polymer network = Enhanced mechanical properties 51. Which conﬁguration is used in Photopolymerization Processesthat irradiates entire layers at one time? A. Liquid resin B. Mask projection C. Two-photon approach D. Vector scan Answer: Mask projection (B) Mask projection is an approach that allows for simultaneous irradiation ofwhole layers. 19 52. Visible light is predominantly used in the microelectronicindustry. A. True B. False Answer: False (B) In the microelectronic industry, far UV and electron beams are commonlyutilized, whereas visible light is mostly used in dentistry. 53. What is a primary beneﬁt of the two-photon approach in photopolymerization? Answer: Recoat is unnecessary as the part is fabricated below the resinsurface. The two-photon approach eliminates the need for recoating, which simpliﬁesthe process. 54. In the....................................................................scan approach, scanning laser beams are needed. Answer: vector The vector scan approach typically requires scanning laser beams for operation. 20 55. What type of radiation is primarily used in photopolymerizationprocesses? A. Ultraviolet (UV) radiation B. Microwave radiation C. Radio waves D. Infrared radiation Answer: Ultraviolet (UV) radiation (A) Photopolymers mainly react to ultraviolet (UV) radiation, although somesystems also use visible light. 56. Match the following photopolymerization conﬁgurations withtheir characteristics: 1. Resin A. Reapplication of resin for each new application layer 2. Mask B. Layer-wise approach with large projection radiation beam 3. C. High resolution with no recoating Vector needed scan D. Point-wise approach with 4. Two- recoating required photon Answer: Vector scan = Point-wise approach with recoating required Mask projection = Layer-wise approach with large radiation beamTwo- photon = High resolution with no recoating needed Resin application = Reapplication of resin for each new layer 21 57. Photopolymers were developed in the 1980s. A. True B. False Answer: False (B) Photopolymers were developed in the 1960s, with signiﬁcant applicationsarising in the following decades. 58. Who is credited with the discovery of producing solid polymerpatterns through UV curing in the mid-1980s? Answer: Charles Hull Charles Hull experimented with UV curable materials, leading to thedevelopment of solid 3D parts through photopolymerization. 59. Photo-curable resins are often used in.................................................. to seal deep grooves in teeth. Answer: dentistry These resins help ﬁll in grooves to prevent cavities in dental applications. 22 60. Match the following types of radiation with their applications incuring photopolymers: 1. Gamma A. 3D printing processes rays B. Some photopolymerization 2. systems X- rays C. Medical imaging and treatment 3. Visible light D. Curing of photopolymers for coatings 4. UV radiation Answer: Gamma rays = Curing of photopolymers for coatingsX- rays = Medical imaging and treatment UV radiation = 3D printing processes Visible light = Some photopolymerization systems 61. What is one of the primary advantages of vat photopolymerization technology? A. Rapid material processing speed B. Automatic support structure generation C. Low material costs D. High accuracy and surface ﬁnish Answer: High accuracy and surface ﬁnish (D) Vat photopolymerization is known for its accuracy and the quality of surfaceﬁnishes. 23 62. Current stereolithography materials possess high impactstrength and durability compared to injection molded thermoplastics. A. True B. False Answer: False (B) Stereolithography materials are limited in impact strength and durability whencompared to traditional thermoplastics. 63. What is the minimum size of a hardened polymer unit producedin microfabrication applications? Answer: 5 µm x 5 µm x 3 µm The speciﬁcations of the microfabrication process deﬁne this minimum unit size. 64. The accuracy of the SLA-250 is................................................... Answer: 0.002 in/in This indicates the level of precision achievable with the SLA-250 system. 24 65. Match the following characteristics with their correspondingtechnologies: 1. Mask A. Speed advantage over laser scanSL Projection VP B. Used primarily for high-resolution 2. microfabrication SLA- 250 C. 5-µm spot size of the UV beam 3. Microsterolithography Precision of 0.002 in/in 4. Two- Photon D. VP Answer: 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 66. Which of the following is a drawback of using photopolymers inadditive manufacturing? A. Incompatibility with injection molds B. High cost of materials C. Ageing leading to degraded mechanical properties D. Limited production speed Answer: Ageing leading to degraded mechanical properties (C) Photopolymers are known to degrade over time, aﬀecting mechanical properties. 25 67. Mask projection technologies are less eﬃcient than laserscanning for SLA processes. A. True B. False Answer: False (B) Mask projection technologies have a speed advantage compared to laserscanning methods. 68. What constrains the chemistry of commercially usedphotopolymers? Answer: Acrylates and epoxies These are the main types of chemicals used in the formulation ofphotopolymers. 69. Which types of radiation are most commonly used to curecommercial photopolymers? A. X-rays and visible light B. Gamma rays and UV C. UV and electron beams D. Visible light and infrared Answer: UV and electron beams (C) UV and electron beams are the most prevalent types of radiation used forcuring photopolymers. 26 70. Photopolymers are primarily used as photoresists in thebiomedical ﬁeld. A. True B. False Answer: False (B) Photopolymers are primarily used as photoresists in the microelectronicindustry. 71. What is the role of a photoinitiator in photopolymer chemistry? Answer: To convert physical energy of light into chemical energy. Photoinitiators generate reactive intermediates which initiate thepolymerization process. 72. In laser scan vat photopolymerization, a UV laser selectivelysolidiﬁes a liquid photopolymer resin to create................................................... Answer: solid parts This process involves building the parts layer by layer using UV lasers. 27 73. Match the following types of polymerization with theirrespective materials: 1. Free radical polymerization A. Vinylether 2. Both B. Acrylate and Epoxy types 3. Cationic C. Epoxy polymerization 4. Vinylether D. Acrylate polymerization Answer: Free radical polymerization = Acrylate Cationic polymerization = Epoxy Vinylether polymerization = Vinylether Both types = Acrylate and Epoxy 74. What is the purpose of the recoater blade in the vector scan vat photopolymerization process? A. It dips the platform to create a new layer. B. It smooths the surface of the vat and deposits new resin. C. It removes unwanted cured parts from the build area. D. It cures the resin after each layer. Answer: It smooths the surface of the vat and deposits new resin. (B) The recoater blade smooths the surface of the vat and deposits a new layer ofresin after each layer has cured. 28 75. Acrylates polymerize through a radical mechanism, whileepoxides polymerize through a cationic mechanism. A. True B. False Answer: True (A) This distinction in polymerization mechanisms is a key characteristic of thesematerials. 76. What is the term for the network formation that occurs whenacrylates and epoxides polymerize? Answer: Interpenetrating polymer network formation This formation results from the diﬀerent polymerization mechanisms ofacrylates and epoxides. 29 Chapter 5&6 1. Which of the following is the ﬁrst commercialized Powder BedFusion process? A. Binder Jetting B. Direct Energy Deposition C. Selective Laser Sintering D. Fused Deposition Modeling Answer: Selective Laser Sintering (C) Selective Laser Sintering (SLS) was the ﬁrst PBF process to be commercialized. 2. Powder Bed Fusion processes include only metallic materials. A. True B. False Answer: False (B) Powder Bed Fusion processes can utilize polymers, metals, and ceramics. 3. What is one of the main powder fusion mechanisms mentioned inPowder Bed Fusion processes? Answer: Liquid-phase sintering Liquid-phase sintering is one of the mechanisms through which powder can befused in PBF processes. 30 4. The ﬁrst PBF process, Selective Laser Sintering, was developed atthe................................................... Answer: University of Texas at Austin This institution was key in the development of the SLS process. 5. Match the following powder fusion mechanisms with theirdescriptions: 1. Chemically A. Fusion through partial melting induced sintering 2. Liquid- B. Fusion without melting of particles phase sintering C. Complete melting of powder 3. Solid- particles state sintering D. Fusion induced by chemical reactions 4. Full melting Answer: Solid-state sintering = Fusion without melting of particles Chemically induced sintering = Fusion induced by chemical reactions Liquid-phase sintering = Fusion through partial melting Full melting = Complete melting of powder particles 31 6. What happens to the rate constant as activation energydecreases? A. It increases B. It remains the same C. It ﬂuctuates D. It decreases Answer: It increases (A) As activation energy decreases, the rate constant increases because less energyis needed for the reaction to occur. 7. The activation energy of a catalyzed reaction is larger than that ofan un-catalyzed reaction. A. True B. False Answer: False (B) The activation energy of a catalyzed reaction is typically much smaller than thatof an un- catalyzed reaction. 8. 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? Answer: 6.37 x 10^-36 M-1s-1 The rate constant is calculated using the Arrhenius equation, yielding thespeciﬁed value. 32 9. Chemically-induced sintering forms a by-product that binds thepowder together with the help of....................................................... reactions. Answer: thermally-activated Chemically-induced sintering relies on thermally-activated chemical reactions tofacilitate the bonding of powders. 10. Match the following reactions to their resulting compounds: 1. Laser processing A. ZrO2 of Al 2. Laser B. AlN processing of ZrB2 3. Laser C. SiO2 processing of SiC Answer: Laser processing of SiC = SiO2 Laser processing of ZrB2 = ZrO2 Laser processing of Al = AlN 33 11. Which of the following is a disadvantage of chemically-inducedsintering? A. Increased density of the product B. High activation energy C. High cost and time in post-processing D. Limited post-processing options Answer: High cost and time in post-processing (C) The cost and time associated with post-processing are signiﬁcant limitations of chemically-induced sintering in commercial applications. 12. Liquid-Phase Sintering (LPS) is the most versatile mechanism forPowder Bed Fusion (PBF). A. True B. False Answer: True (A) Liquid-Phase Sintering (LPS) is indeed recognized as the most versatilemechanism used in Powder Bed Fusion (PBF). 13. At what temperature is the rate constant 7 M-1s-1? Answer: 389K The speciﬁed temperature of 389K has a rate constant of 7 M-1s-1 in the contextof the Arrhenius equation. 34 14. Which of the following processes is primarily used for producingplastic prototypes? A. Electron Beam Melting B. Laser Sintering C. Powder Bed Fusion D. Selective Laser Sintering Answer: Laser Sintering (B) Laser Sintering is a common process utilized for creating plastic prototypes. 15. Thermoset polymers can be processed using Powder Bed Fusioninto parts. A. True B. False Answer: False (B) Thermoset polymers typically degrade and do not melt, making themunsuitable for PBF. 16. What is the typical thickness of the powder layers used in thepolymer laser sintering process? Answer: 0.075 - 0.1 mm The thickness of the powder layers is crucial for successful fusion during theprocess. 17. The build chamber for polymer laser sintering is ﬁlled with.................................................. gas to minimize oxidation. Answer: nitrogen Using nitrogen helps protect the powdered material from degradation. 35 18. Match the following materials with their classiﬁcation: 1. Cobalt- A. Thermoplastic polymer chromium 2. B. Ceramic Alumina 3. C. Metal alloy Nylon 4. D. Metal Titanium Answer: Nylon = Thermoplastic polymer Titanium = Metal Alumina = Ceramic Cobalt-chromium = Metal alloy 19. Which of these materials is commonly known to be processedusing Powder Bed Fusion? A. Thermoset polymers B. Fiber-reinforced plastics C. Thermoplastic polymers D. Wood composites Answer: Thermoplastic polymers (C) Thermoplastic polymers are commonly used in Powder Bed Fusion due to theirmelting properties. 36 20. Infrared heaters are used in the polymer laser sintering process. A. True B. False Answer: True (A) Infrared heaters are essential for maintaining an elevated temperature aroundthe part being formed. 21. What are the two types of molecular structures found inthermoplastic polymers? Answer: Amorphous and Crystalline Amorphous polymers have random structures, while crystalline polymers haveregular structures. 22. PBF technology is increasingly used for direct digital manufacturing of products. Answer: end-use This method is eﬀective for creating products that can be used in actualapplications. 23. Which of the following materials is NOT typically processed withPowder Bed Fusion? A. Ceramic compounds B. Cobalt-chromium alloys C. Thermoset polymers D. Stainless steel Answer: Thermoset polymers (C) Thermoset polymers cannot be processed using PBF due to their degradation. 37 24. What is the primary purpose of LPS in powder processing? A. To promote the wear of cutting tools B. To completely melt all powder constituents C. To act as a glue binding solid particles together D. To increase the melting point of particles Answer: To act as a glue binding solid particles together (C) LPS, or liquid-phase sintering, primarily acts as a binder to fuse solid powderparticles together. 25. LPS can be used in additive manufacturing as a fusionmechanism. A. True B. False Answer: True (A) LPS can indeed be utilized as a fusion mechanism in additive manufacturingprocesses. 26. What is the common material used in PBF processing? Answer: Nylon polyamide Nylon polyamide is widely used in powder bed fusion (PBF) processes due to itssemi- crystalline properties. 27. In LPS, the molten constituent acts as the.............................. which binds the solid particles together. Answer: glue The molten constituent in LPS functions as the binding material that holds solidparticles together. 38 28. Which of the following materials is NOT typically used in PBFprocessing? A. Cobalt Chromium B. Cemented Carbide C. Titanium D. Stainless Steel Answer: Cemented Carbide (B) Cemented carbide is not typically processed using PBF methods as compared tothe other materials listed. 29. Match the following terms with their descriptions: 1. A. Fusion of powder particles where PB some constituents melt F B. Process that melts the entire 2. region of material LPS C. Common material used in PBF 3. Co D. Low melting point constituent in cemented carbide tools 4. Nylon Polyamide Answer: LPS = Fusion of powder particles where some constituents meltPBF = Process that melts the entire region of material Nylon Polyamide = Common material used in PBF Co = Low melting point constituent in cemented carbide tools 39 30. Full melting means that only a portion of the material is meltedduring PBF processing. A. True B. False Answer: False (B) Full melting refers to the complete melting of the material subjected toimpinging heat energy. 31. What are two engineering alloys mentioned as utilized in PBFprocessing? Answer: Titanium and Stainless Steel Titanium and Stainless Steel are two examples of engineering alloys commonlyused in powder bed fusion processing. 32. What is a characteristic of an electron beam when it interactswith gas at atmospheric pressure? A. It heats the gas particles. B. It is signiﬁcantly enhanced. C. It passes through unaﬀected. D. It is deﬂected. Answer: It is deﬂected. (D) Electrons interacting with gas are subject to deﬂection due to their interactionswith atoms. 40 33. A laser beam requires a vacuum environment to functioneﬀectively. A. True B. False Answer: False (B) A laser beam can pass through a gas unaﬀected as long as the gas is transparent at the laser wavelength. 34. What is one of the primary beneﬁts of using Powder Bed Fusionover other additive manufacturing processes? Answer: It can process a wide variety of materials. PBF oﬀers versatility in material processing compared to many other methods. 35. PBF processes typically have accuracy and surface ﬁnish that are.................................................. compared to liquid-based processes. Answer: inferior The operating conditions and particle size can signiﬁcantly aﬀect the quality ofparts produced via PBF. 41 36. Match the following terms with their descriptions related toPowder Bed Fusion processes: 1. Total part A. Facilitates easier powder construction processing time 2. Loose B. Produces smoother, more accurate powder parts during part building C. Can take longer due to preheatand 3. cool-down cycles Larger particle size D. Suﬃcient support material for polymer PBF 4. Finer particle size Answer: Finer particle size = Produces smoother, more accurate partsLarger particle size = Facilitates easier powder processing Loose powder during part building = Suﬃcient support material forpolymer PBF Total part construction time = Can take longer due to preheat and cool-down cycles 42 37. Which of the following describes one possible process parameterthat can inﬂuence the ﬁnal microstructure of materials in Powder Bed Fusion? A. Beam wavelength B. Powder particle size C. Production environment pressure D. Material viscosity Answer: Powder particle size (B) The powder particle size directly inﬂuences the surface ﬁnish and accuracy ofthe parts. 38. Materials with high thermal conductivity typically producebetter accuracy in Powder Bed Fusion processes. A. True B. False Answer: False (B) Materials with low thermal conductivity lead to better accuracy. 39. What is a common drawback of using larger powder particlesizes in Powder Bed Fusion? Answer: It hurts surface ﬁnish and minimum feature size. While larger sizes are easier to handle, they negatively impact the quality of theﬁnal parts. 43 40. What is primarily used in Polymer Laser Sintering (pLS)machines to create parts? A. CO2 lasers B. UV lasers C. High-energy electron beams D. Nd-YAG lasers Answer: CO2 lasers (A) Polymer Laser Sintering machines use CO2 lasers for the processing of polymers. 41. Electron Beam Melting (EBM) uses laser beams for metal fusion. A. True B. False Answer: False (B) EBM uses high-energy electron beams, not laser beams, to fuse metal powderparticles. 42. What materials are commonly processed in Polymer LaserSintering machines? Answer: Nylon polyamide materials Nylon polyamide materials are among the most popular materials used inPolymer Laser Sintering processes. 43. In EBM, a stream of................................................................................moving near the speed of light is used for particle fusion. Answer: electrons EBM employs a high-energy stream of electrons to induce fusion between metalpowder particles. 44 44. Match the following PBF process variants with their maincharacteristics: 1. Selective A. Uses lasers to process polymersand Laser indirectly process metals. Sintering (SLS) 2. B. Commonly refers to laser-based Polymer sintering processes. Laser Sintering (pLS) C. Designed for processing a varietyof powdered polymer materials. 3. Laser Sintering (LS) D. Uses high-energy electron beamsfor metal fusion. 4. Electron Beam Melting (EBM) Answer: Selective Laser Sintering (SLS) = Uses lasers to process polymers and indirectly process metals. Electron Beam Melting (EBM) = Uses high-energy electron beams for metalfusion. Polymer Laser Sintering (pLS) = Designed for processing a variety of powdered polymer materials. Laser Sintering (LS) = Commonly refers to laser-based sintering processes. 45 45. Which of the following statements about the atmosphere inPolymer Laser Sintering machines is true? A. They require a hydrogen atmosphere. B. They operate in a vacuum environment. C. They maintain approximately 20-30% oxygen. D. They use nitrogen with approximately 0.1-3.0% oxygen. Answer: They use nitrogen with approximately 0.1-3.0% oxygen. (D) pLS machines utilize nitrogen atmosphere with a low percentage of oxygen foreﬀective polymer processing. 46. PLS machines are capable of directly processing pure metals. A. True B. False Answer: False (B) pLS machines are not designed to directly process pure metals; they workmainly with polymers and indirectly with metals. 47. What is the primary advantage of using Electron Beam Meltingcompared to laser- based systems? Answer: It uses a high-energy electron beam for fusion, allowing diﬀerentprocessing capabilities. EBM provides diﬀerent processing advantages by using electron beams insteadof lasers. 46 48. Which of the following is a primary approach used in extrusionprocesses? A. Using mechanical pressure to shape materials B. Using only thermal controls for material liquefaction C. Using electrical voltage to control ﬂuidity D. Using chemical changes for solidiﬁcation Answer: Using chemical changes for solidiﬁcation (D) Extrusion processes utilize both thermal controls and chemical changes forsolidiﬁcation. 49. Fused deposition modeling (FDM) requires a ﬁxed horizontalposition for the extruder. A. True B. False Answer: False (B) FDM systems use a vertically mounted extruder that can move along a plottingsystem. 50. What is the purpose of bonding in extrusion-based systems? Answer: To ensure that materials adhere properly during the extrusionprocess. Bonding is critical for the structural integrity of parts produced in extrusionsystems. 47 51. In extrusion-based systems, the term.................................................. refers to the control of the extruder'sposition during the printing process. Answer: Positional control Positional control is essential for accurate layering and shaping in additivemanufacturing. 52. Match the following FDM related terms with their descriptions: 1. A. Extrusion processes tailored for Bioextrusion biocompatible materials 2. Melt B. The process of melting materialsfor extrusion deposition 3. Scaﬀold C. Structures designed to support theof architectures growth cells in biomedical applications 4. Gel formation D. A state where material transitions into a gel before solidiﬁcation Answer: Gel formation = A state where material transitions into a gel before solidiﬁcation Scaﬀold architectures = Structures designed to support the growth of cellsin biomedical applications Melt extrusion = The process of melting materials for deposition Bioextrusion = Extrusion processes tailored for biocompatible materials 48 53. What limitation is often associated with FDM? A. High material viscosity B. Exclusively for metal applications C. Limited choice of extrudable materials D. Requires extremely cold temperatures Answer: Limited choice of extrudable materials (C) FDM is often limited by the range of materials that are suitable forbiocompatibility. 54. Contour crafting is considered one of the other systems inextrusion-based methods. A. True B. False Answer: True (A) Contour crafting is a method that falls under the category of extrusion-basedsystems. 55. What is the signiﬁcance of solidiﬁcation in the extrusion-basedprocess? Answer: Solidiﬁcation ensures that the extruded material maintains itsshape and structural integrity. Without solidiﬁcation, the printed structures would collapse or deform. 49

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