exam 1 fall 07 solutions - PART 1 MULTIPLE CHOICE& SHORT...

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Unformatted text preview: PART 1. MULTIPLE CHOICE & SHORT QUESTIONS (50 points) 1) The reading from a micrometer in Fig. 1 is ’9, . W is ‘L inch (list 4 decimal places) 2) The reading from a micrometer in Fig. 2 is {a a if S 1 mm (list 3 decimal places). m ' ' Fig. 1: A micrometer with 2-3 inch range. 3) The defects in injection molding include: a) Bambooing, die swell, sink mark, and airtrap. b) Airtrap, weldline, short shot, and drag flow. c) Flashing, sink mark, weldline, and die swell. d) 'None of the above. Liquid (L) .4 O . 0 0 723°C (1333°F) Temperature, “C a 4- F930 Solid a 4 Fe. % Carbon (C) C Fig. 3: Phase diagram 4) Referring to the phase diagram in Fig. 3, select the best sentence from: a) A steel, with eutectic composition, has the lowest melting temperature of 2066°F. b A steel, with eutectoid composition, has the lowest melting temperature of 1333°F. \ c) _» A cast iron, with eutectic composition, has the lowest melting temperature of 2066°F. . d) A cast iron, with eutectoid composition, has the lowest melting temperature of 1333°F. 5) Considering blow molding process, select the incorrect sentence among: a) ,f The diameter swelling ratio is higher than that Of the thickness swelling ratio. 1)) The volume of parison polymer equals that of the product. 0) A thicker product wall thickness means higher air molding pressure is allowed. (1) The hoop stress is higher than the axial stress. 6) Compare the machining characteristic of tools with positive and negative rake angles using two criteria of your choice. Answer: Fig. 5: Gray cast iron microstructure. The dark areas are :_a ahite flakes m white' 11'011 matrix. Fig. 6: Plastic products. 7) Microstrueture of cast iron is shown in Fig. 5. How does graphite (carbon) contribute to machining property of cast iron? swer: ‘ flaihi+ A u Anw’ful Mi] «Ar-M busts 99:8be .—_—> H3 “figfifief 8) Fig. 6 shows a hollow plastic road divider (A) and fan blade (B). The suitable processes to manufacture them (in correct order) are: . a) Injection molding, extrusion. b) Injection molding, rotation molding. Rotation molding, injection molding. Compression molding, injection molding. 9) An aluminum bar is turned from 91.25 inch to 0 0.85 inch at 500 RPM on a lathe. What is the depth of cut for this operation? Answer: A: MllrlA-iO‘E; I 012 indq 10) Cite four safety violations in a machining shop. L ”mi We.” Cam slew PART 2: OPTIONAL PROBLEM (25 points) An engineer machines nickel-based alloy orthogonally. This material has tensile strength of 620 MPa (90,000 psi). A dynamometer attached to the workpiece allows measuring of difi'erent cutting forces during the experiment. Other machining parameters are: a Tool material: high speed steel 0 Width of out: 3.5 mm (0.138 inch) - Shear angle: 35° I Cutting force: 250 N (56 lbf) 0 Cutting fluid: oil 0 Depth of cut: 1.0 mm (0.040 inch) 0 Machine tool capacity: 1.65 HP 0 Tool: 5° relief angle, 0° top rake angle, 0 Machine tool efficiency: 0.88 0.70 mm (0.003 inch) radius Using SI units, show all your work to find: a) The maximum cutting speed in this experiment. b) The normal force (perpendicular to the fi'iction force). N «E; WON ~ g 3.“... = m... WM W e e \l_"-' #3? ("q/5 lg) WW1} Mermd's mafia . [email protected]*°’\):f§ QWLE Mb} Wwdfio as? = 91" (23569-9() :crt? => ESN 2'56““ PART 3. PROCESS PLAN (40 points) Figure 7 shows the assembly drawing of a clamp. The stainless steel threaded rod (#7) is inserted through the threaded hole of hinge B (#6) and into the through hole of hinge A (#5). The whole clamp can fit into a box of 8 x 5 x 3 cubic inches. - a) Suggest a specific material for the hinges (i.e., SAE nomenclature). 1)) Prepare a process plan to mass produce the hinge A using only the processes discussed in class so far. Ignore the part dimension and state your assumption(s) if there is any. Note: Use a table format. For each step you should label the step, suggest correct process name and write short notes to explain the step, and then sketch the relative position of a cutting tool, its direction, and the evolving workpiece. No essay, please! 9 DESCRIPTION 51* at -4 E SUPPORT LEI-7'8: RIG QUICK ACTING HOLD-DOWN CLAMP I Figure 7. A mechanical clamp. Material:? [OH-S" 9413-9. Mi # I W Le : amt! m AM}. j, 8) AM“ W93 - m9.» q) [450% ; Noam“? galm gfiwmhzr , Mn 7 5) DC 15'qu ...
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