Quiz set 2 f23

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Purdue University *

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Mechanical Engineering

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Jan 9, 2024

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Quiz set 2 Quiz 10 True of False (1-3) 1. The higher the aspect ratio of a fiber, the stronger it should be. T 2. Carbon-carbon FRCs get stronger as the temperature increases. T 3. Metal matrix composites are typically strong, stiff, conductive, and ductile. T 4. When a melted plastic flows smoothly and uniformly into a mold, its flow is probably _______ A. Laminar B. Turbulent C. unknown (cannot be determined) 5. The process for making the largest number of thermoplastic parts is ________ A. Compression molding B. Casting C. Injection molding Quiz 11 True or False 1. To address swell compensation, extrusion dies for parts with straight sides curve inward. T 2. Extrusion must be embedded into other molding processes. F 3. It is not physically possible for extruded parts to have knit lines. F 4. DLLR should be at least 3:1. F Quiz 12 1. The parting line is generally “hidden” on injection molded parts. ( Ture or False) 2. Cooling channels are only necessary for hot-runner injection molding processes. (Ture or False ) 3. For a cylindrical shampoo bottle with a blow ratio of 3 and a parison diameter of 20 mm, its bottle diameter is: A. 6.67 mm B. 20 mm C. 30 mm D. 60 mm 4. The preferred blow molding process for bottles that will be pressurized is ____ A. extrusion blow molding B. injection stretch blow molding C. injection blow molding

Quiz 13 (True or False) A microwave food tray is approximately 4” by 4”, with a depth of 1”. The tray’s base area of 16 in 2 plus four side areas of 4 in 2 each gives a surface area of 32 in 2 . (For Q1-2 ) 1. The tray’s areal draw ratio is 4:1. False – Ratio is surface Area/footprint = (32/16) = 2:1 2. A plug assist is not necessary for vacuum thermoforming the tray. True – Draw Ratio, DR = 1:4; use a plug assist if DR is above 2.5:1. 3. Rotational molding is potentially a good method of manufacturing storage and trash bins. T 4. Vacuum (reduced) pressure is an important rotational molding process consideration. F 5. In rotational molding, the major axis and minor axis refer to the axes of rotation of the molding machine. T Quiz 14 • A. Extrusion B. RIM (reaction injection molding) • C. Pultrusion D. Compression molding • E. Vacuum Bag method 1. The __D__ is the most common thermoset process which shapes thermosets or composites in granule, parison, preform, or putty-like (BMC, SMC) form. 2. ___A___ applies especially to thermosetting elastomers (as well as thermoplastics and laminar composites). 3. __B__ produces heat as part of its process. 4. __C__ is a two-step process where fibers are pulled first through a thermoset bath, then through heated dies. 5. The __E_ composite process relies on combining liquid thermoset resin matrix and reinforcement material with heat and negative pressure in an autoclave. Quiz 15 1. One of the steps for narrowing down the process for making a product is to screen using constraints. T 2. Materials selection for a product is based solely on intended use. F 3. Functional design of a product establishes its appearance and behavior. T

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