exam 2 fall 07 solutions

exam 2 fall 07 solutions - PART 1. MULTIPLE CHOICE...

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Unformatted text preview: PART 1. MULTIPLE CHOICE & SHORT QUESTIONS (50 points) 1) The reading from a micrometer in Fig. l is i. \ Li ‘L “i '5, inch (list 4 decimal places) 2) The reading from a micrometer in Fig. 2 is m (list 3 decimal places). Fi . 1: A micrometer with 2-3 inch ran e. Fig. 2: A micrometer with O-25mm range. 3) Referring to Figs. 3a and 3b, the processes to form these metal sheets (in correct order) are: a) Hemming and seaming. b) Hemming and curling. c) Lancing and flanging. d) Flanging and hemming. 4) Suggest a suitable process to economically carve a decorative egg shell (Fig. 4). Briefly justify your suggestion. _ i _ ‘ . . " (-1 . ‘ : r x l ‘ - ' ( b) Fig. 3‘. Sheet metal processes 5) A filler rod is commonly used with: a) Resistance spot welding. b) Electron beam welding. (3):“ Shielded metal arc welding. ' H) Solid state welding. 6) Name two advantages and two disadvantages of chemical etching. Answer: *7 :3 ii a x, ,- é. 5:VWeld beds 7) Select the best weld bead (choose a letter from Fig. 5) and briefly state your reason. Answer: Olan £211" UMI’C‘IW‘ Ema; mist (and thlm’itm \ 8) The strain hardening exponent of lead is practically zero at 200°C, then: a) Its tensile strength is the same as the strength coefficient. b) Its flow stress is the same as the yield strength. 0 Nether (a) and (b) is correct. Both (a) and (b) are correct. 9) Comment on the weld quality of 1010 and 1045 steels when welded with shielded metal are process: a) The weld on 1010 steel will have more slag. b) The weld on 1045 steel will have more slag. @ The weld on 1010 steel will have less chance for crack and be stronger. d) The weld on 1045 steel will have less chance for crack and be stronger. 10) An undercut is often associated with: Chemical etching. . Excimer laser drilling. 0) Electrical discharged machining. d) All of the above. PART 2: OPTIONAL PROBLEM 25 oints Electrode holder ./ Figure 6 shows the setup for gas Electrode (consumaelgmm tungsten arc welding. Since no tungsten ‘ is deposited in the weld, a filler rod is Dnecflon oftrave,+_ . Heweiding “acme - — I r a I or nonconsumable) E act Ode C b a used with this process for butt—welding m of 1040 steel. The filler material then _ :5 power . _ _ ._ weid metal contributes to 80% of the weld volume. , , some Motion weld metal e” Clamp \7 Work came Fig. 6: GTAW welding Given: Welding current: 25 amp Welding voltage: 32 volt DC Electrode size: (32.5 mm (0.098 in) Filler rod size: (2)3 mm (0.1 18 in) Shielding gas: C02 Gas flow rate: 0.14 mglmin (5 iii/min) Consuming rate of filler rod: 2 rum/s (0.079 infs) Sectioned weld area (below surface): 40 mm2 (0.062 inz) Arc area (on weld surface): 10 mm2 (0.015 inz) Steel tensile strength: 300 MPa (45 ksi) Steel yield strength: 175 MPa (25 ksi) Steel melting point: 1400°C (25500F) Unit melting energy: 9.32 J/mm3 (133 Btu/ma) 1) Should the electrode be connected to positive or negative end of the power supply? Why? 2) Calculate the power density. 3) Calculate total heat loss as percentage of the power source. 1 I i (. (fir C? p v ‘ r. ‘ 1 K, 1 r , u ; I a 4. r J, Lt‘i‘fl I i m“ [‘1 Erin“ “ l g a ll ,. .. l"- (‘1 V I :5 l 2‘_ . F f a a " '1 ‘t mi t‘ in”; k g f . .. a I 13 a {ll L PART 3. PROCESS PLAN 40 Figure 7 shows a set of garden tool. Each 8-inch metal part is mass-produced then inserted into a wooden handle. Your task is to revise the design and manufacture of the metal parts to minimize their cost. 1. Suggest a material for the trowel and its raw material form (shape and size). 2. Prepare a step-by-step process plan to mass-produce this tool using only the processes discussed in class so far. Ignore the dimensional details and state your assumption(s) if there is any. Note: Use a table format. For each step you must label the step, name specific process (as written in our textbook), write .l ‘ C (91% r mutiny-1t: PM 9 2 Hf litigant Fact :1; {r 1 [mi N». thorax} page, C ‘ ’5 Qiflflfir VOC‘i +3- liglnf'téfl :3 L} bend 795i. Z Skiff qu ,3Ufics‘: \ a 5 Wald mi iv 196mm; Fast Wn‘. it? TI‘G from $5: 6 CiQ if?“ V Y. C1?- {it {Pl £»(€¥‘2‘._ 'i'tl LU i) sit“: €199» If“. l ...
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exam 2 fall 07 solutions - PART 1. MULTIPLE CHOICE...

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