Midterm Exam-II Chapter 3&4 Answers PDF

What is the primary purpose of converting a CAD model to STL format? A. To export as a 3D printing file B. To create a detailed engineering drawing C. To enhance the visual quality of the model D. To simplify the model\'s geometry for AM ANSWER: D The conversion to STL format is a manual proce...

What is the primary purpose of converting a CAD model to STL format? A. To export as a 3D printing file B. To create a detailed engineering drawing C. To enhance the visual quality of the model D. To simplify the model\'s geometry for AM ANSWER: D The conversion to STL format is a manual process requiring significant user intervention. A. True B. False ANSWER: B Name one application area of additive manufacturing that does not involve conventional CAD modeling. ANSWER: 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. ANSWER: machine setup Match the type of additive manufacturing system with its description: Molten material systems \| Utilize powdered materials that are fused together Solid sheets \| Use light to cure liquid resin Powder-based systems \| Extrude melted materials layer by layer Photopolymer based systems \| Adhere layers of sheet materials together ANSWER: 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 What are common considerations in the design for additive manufacturing? A. Part orientation and removal of supports B. Cost of materials C. Material color and texture D. Packaging and shipping dimensions ANSWER: A Energy density is an important factor in metal additive manufacturing systems. A. True B. False ANSWER: A What is one of the initial actions required prior to building a part? A. Ignore part orientation B. Verify the part is incorrect C. Skip the machine setup D. Use the visualization tool ANSWER: D What is the significance of part removal and cleanup in the additive manufacturing process? ANSWER: Ensures the final product is ready for use and free of excess material. All AM machines must run a variety of materials with numerous setup parameters. A. True B. False ANSWER: B What is the purpose of repositioning the part before building? ANSWER: To allow it to be built at a specific location within the machine. Parts may require \_\_\_\_\_ or coating allowances. ANSWER: shrinkage Match the following actions with their related descriptions: Segmentation of STL files \| Divide parts for easier handling Manual finishing \| Configure parameters for operation Verify the part \| Prepare parts for final use Machine setup \| Ensure accuracy before building ANSWER: 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 During which phase does the process switch to computer-controlled building? A. Initial manual stages B. Machine setup phase C. Removal and cleanup phase D. Layer-based manufacturing phase ANSWER: D All AM machines alert the user when the build is complete or when there is no source material remaining. A. True B. False ANSWER: A What does significant manual finishing typically entail for parts produced by AM machines? ANSWER: It involves cleaning and preparing parts for ready-to-use condition. What is the role of support structures in additive manufacturing? A. To enhance the color of the part B. To stabilize the part during the building process C. To improve thermal conductivity D. To reduce production time ANSWER: B Post-processing tasks always require the use of power tools. A. True B. False ANSWER: B What are some common post-processing techniques used in additive manufacturing? ANSWER: Abrasive finishing, polishing, sandpapering, and application of coatings. AM materials often have small \_\_\_\_\_\_\_\_\_\_\_\_\_\_ trapped inside them, leading to potential failure under stress. ANSWER: voids What is a potential consequence of poor technique in support removal? A. Faster production times B. Low quality output of the part C. Increased costs of production D. Enhanced performance of the part ANSWER: B Match the additive manufacturing issues with their descriptions: Anisotropic properties \| Different properties in different directions Material degradation \| Often requires manual skill to avoid damaging parts Support removal \| Material not bonding or crystallizing optimally Application specificity \| Varies by the requirements of the final product ANSWER: 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 Many applications using AM processes do not require high performance from their \_\_\_\_\_\_\_\_\_\_. ANSWER: components Why may parts produced by additive manufacturing behave differently than those made by conventional methods? ANSWER: They may have voids, anisotropic properties, or material degradation. What is the nominal layer thickness range for most SL technology machines? A. 0.2 - 0.3 mm B. 0.05 - 0.1 mm C. 0.1 - 0.2 mm D. 0.01 - 0.05 mm ANSWER: B Thicker layers in additive manufacturing (AM) lead to parts being built more precisely. A. True B. False ANSWER: B What material property must be considered during post-processing that involves heat? ANSWER: Heat resistance or melting temperature In powder-based systems, there is no need to use \_\_\_\_\_\_\_\_\_\_. ANSWER: supports Match the following AM technologies with their characteristics. Binder Printing \| Requires support from the same material used for the part Droplet Deposition \| Parts can be colored using colored binder material Photopolymer-Based Systems \| Deposits a bed of powder layer-by-layer Powder-Based Systems \| Possible to modify the support material as it prints ANSWER: 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 What is an advantage of photopolymer-based systems? A. Good accuracy with thin layers B. Faster build times with thicker layers C. No need for supports D. Superior mechanical properties ANSWER: A Newer resins in photopolymer systems offer improved temperature resistance and strength. A. True B. False ANSWER: A What type of machine typically has a nominal layer thickness of 0.254 mm? ANSWER: FDM Dimension machines What is a key requirement for molten material systems that melt and deposit materials in a molten state? A. Advanced CAD modeling B. Immediate cooling C. Use of laser technology D. Support structures ANSWER: D Extrusion processes like FDM always generate supports automatically. A. True B. False ANSWER: B What is one of the challenges faced when cleaning parts produced by lamination methods? ANSWER: The laborious process of waste material removal. Exposure to \_\_\_\_\_ and excessive light should be avoided in material handling. ANSWER: moisture Match the following application areas with their respective technology: FDM \| Medical modeling Computerized Tomography (CT) \| Additive Manufacturing 3D ultrasound \| Medical modeling Magnetic Resonance Imaging (MRI) \| Medical modeling ANSWER: Computerized Tomography (CT) = Medical modeling Magnetic Resonance Imaging (MRI) = Medical modeling 3D ultrasound = Medical modeling FDM = Additive Manufacturing Which of the following is NOT a factor to consider in metal systems? A. Color of the material B. Energy density C. Speed D. Weight ANSWER: A List two design considerations for additive manufacturing. ANSWER: Part orientation, Removal of supports Some machines in additive manufacturing must be kept away from \_\_\_\_\_ environments. ANSWER: dirty or noisy Which of the following is a type of Vat Photopolymerization process? A. Selective Laser Sintering B. Stereolithography C. Binder Jetting D. Fused Deposition Modeling ANSWER: B Two-Photon Vat Photopolymerization offers only advantages and no drawbacks. A. True B. False ANSWER: B What is one of the key components of photopolymer chemistry? ANSWER: Photo initiator system The process that models irradiance and exposure in Vat Photopolymerization is known as \_\_\_\_\_\_\_\_\_\_. ANSWER: Photopolymerization Process Modeling Match the following scan patterns with their descriptions: WEAVE \| A complex pattern designed for intricate builds Layer-based build phenomena \| An advanced vector scan pattern for enhanced accuracy ACES \| Patterns related to the construction of layers in photopolymerization STAR-WEAVE \| A pattern that helps in smooth layering ANSWER: 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 Which of the following radiation types is primarily used to cure commercial photopolymers? A. X-rays B. Gamma rays C. UV light D. Infrared light ANSWER: C Epoxy and vinylether are examples of free radical polymerization. A. True B. False ANSWER: B What is the role of a photoinitiator in photopolymerization? ANSWER: To convert physical energy of light into chemical energy in the form of reactive intermediates. Photopolymer resins must be cleaned, post-cured, and \_\_\_\_\_\_\_\_ after building. ANSWER: finished Match the following photopolymerization processes with their respective characteristics: Cationic polymerization \| Acrylates and epoxides form networks Interpenetrating polymer networks \| Uses multifunctional monomers Resin formulation \| Acrylate-based Free radical polymerization \| Epoxy and vinylether ANSWER: Free radical polymerization = Acrylate-based Cationic polymerization = Epoxy and vinylether Resin formulation = Uses multifunctional monomers Interpenetrating polymer networks = Acrylates and epoxides form networks What component of the laser scan VP machines is responsible for liquid resin application? A. Control system B. Vat system C. Platform system D. Recoating system ANSWER: D Both di-functional and higher functionality monomers are commonly used in SL resins. A. True B. False ANSWER: A Name two main subsystems of vector scan VP machines. ANSWER: Laser and optics systems, control system. Which approach in photopolymerization does not require recoating of the resin layer? A. Two-photon approach B. Layer-wise approach C. Vector scan approach D. Mask projection approach ANSWER: A In the microelectronic industry, visible light is predominantly used for photomask materials. A. True B. False ANSWER: B What device is used to pattern the large radiation beam in the mask projection approach? ANSWER: Digital Micromirror Device In photopolymerization processes, the \_\_\_ scan approach is typical of commercial SL machines. ANSWER: vector Match the photopolymerization approaches with their descriptions: Two-photon \| High resolution point-by-point Layer-wise \| Successive layer applications Mask projection \| Scanning laser beams needed Vector scan \| Entire layers irradiated at once ANSWER: 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 What type of light is primarily used in photopolymerization processes? A. Ultraviolet (UV) B. Infrared C. X-ray D. Visible light ANSWER: A Charles Hull discovered solid polymer patterns by exposing UV curable materials to a scanning laser. A. True B. False ANSWER: A What is one common application of photo-curable resins in dentistry? ANSWER: Sealing the top surfaces of teeth to prevent cavities The mid 1980s marked the beginning of SL technology due to Charles Hull\'s experiments with \_\_\_\_\_ curable materials. ANSWER: UV Match the following radiation types with their uses in curing commercial photopolymers: Ultraviolet rays \| Primarily used in photopolymerization processes X-rays \| Used in various curing applications Visible light \| Alternative curing method Gamma rays \| Used in treating medical materials ANSWER: 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 What is a significant drawback of vat photopolymerization technology? A. High production speed B. Superior mechanical properties C. Low material flexibility D. Limited chemistries for photopolymers ANSWER: D The surface finish of SL parts can range from submicron to over 100 um Ra depending on the orientation of the surfaces. A. True B. False ANSWER: A What is the maximum size of fabrication structure achievable with the specified microsterolithography process? ANSWER: 10 mm x 10 mm x 10 mm The minimum size of a hardened polymer unit in the microsterolithography process is \_\_\_ in the x and y directions. ANSWER: 5 µm x 5 µm Match the advantages of vat photopolymerization technology with their descriptions: Surface finish \| Varies based on surface orientation Accuracy \| Supports different configurations Speed \| Fast production compared to laser scanning Flexibility \| 0.002 in/in ANSWER: Accuracy = 0.002 in/in Surface finish = Varies based on surface orientation Flexibility = Supports different configurations Speed = Fast production compared to laser scanning Which of the following statements about mask projection VP technologies is true? A. They are faster compared to laser scan SL technologies. B. They do not produce intricate designs. C. They support only one machine configuration. D. They have a slower production speed than laser scan SL. ANSWER: A Photopolymers used in additive manufacturing are known for their exceptional impact strength and durability. A. True B. False ANSWER: B What is the position accuracy achieved in the x-y directions during the microsterolithography process? ANSWER: 0.25 µm When laser light is focussed on a particular area for a long time, then that particular area alone will be heated.\ A. True\ B. False ANSWER: A Laser technology is well suited for integration into modern systems like CAD and CAM? A. True\ B. False\ Answer: A Electromagnetic waves that applied in Mobile Phones are called: A. Infrared waves B. Microwaves C. Radio waves D. Visible light ANSWER: C Purposes of laser material processing is based on the Interaction of lasers with solid materials? A. True B. False ANSWER: A The Relations between the wavelength λ and Frequency is: A. Directly proportional B. Inversely proportional C. There are the same D. No Relation ANSWER: B All the radiation in the Electromagnetics waves have the same wavelength? A. True B. False ANSWER: B What is the full form of LASER and the acronym stand for? A. Light Absorbent and Stimulated Emission of Radiations B. Light Absorbing Solar Energy Resource C. Light Amplification by Stimulated Emission of Radiations D. Light Amplification of Singular Emission of Radiations ANSWER: C The Smallest particle (Quantum) in Light is called \_\_\_\_\_\_\_\_\_\_\ A. Electrons\ B. Photons\ C. Protons\ D. Neutrons ANSWER: B