ME470, Engineering Design Processes and Methodology Mid-Term Exam, Spring, 2011 Name:______________________________________________________________ 1. (10 points) Your company is trying to select a welding process to use in the construction of steam drums for a pressurized water reactor. The company is considering several different welding procedures. In order to choose between the procedures, the weld lab has fabricated the required test specimens for testing. The data is from tensile tests and stronger is better. The statistical results of the test are shown below: Tukey 95.0% Simultaneous Confidence Intervals Response Variable Strength All Pairwise Comparisons among Levels of Process ID Process ID = F123 subtracted from: Process ID Lower Center Upper -----+---------+---------+---------+- M123 -539.6 -457.5 -375.5 (-*-) Sa123 -261.8 -179.8 -97.8 (-*-) Su123 -37.0 45.0 127.0 (-*--) Th123 -131.2 -49.1 32.9 (--*-) Tu123 -398.3 -316.3 -234.3 (-*-) W1234 -248.5 -166.5 -84.4 (-*--) -----+---------+---------+---------+- -350 0 350 700 What Process IDs are not statistically separable from F123 at the 95% confidence limit? Assume that the company wants the highest strength process with the lowest cost. Given the following cost data for each process per linear foot, which process would you choose? Explain your reasoning. Process ID Cost per linear foot F123 $110.00 M123 $25.00 Sa123 $65.00 Su123 $115.00 Th123 $95.00 Tu123 $85.00 W1234 $135.002. (30 points) Parts manufactured in an injection molding process are showing excessive shrinkage. This is causing problems in assembly operations downstream from the injection molding area. A quality improvement team has decided to use a designed experiment to study the injection molding process so that shrinkage can be reduced. The team decided to investigate six factors – mold temperature, screw speed, holding time, cycle time, gate size and holding pressure – each at two levels with the objective of learning how each factor affects shrinkage and also, something about how the factors interact. The team decides the use the 16-run, two-level fractional factorial design shown below. Run MoldTemp ScrewSpeed HoldTime CycleTime GateSize HoldPress Shrinkage 1 -1 -1 -1 -1 -1 -1 6 2 1 -1 -1 -1 1 -1 10 3 -1 1 -1 -1 1 1 32 4 1 1 -1 -1 -1 1 60 5 -1 -1 1 -1 1 1 4 6 1 -1 1 -1 -1 1 15 7 -1 1 1 -1 -1 -1 26 8 1 1 1 -1 1 -1 60 9 -1 -1 -1 1 -1 1 8 10 1 -1 -1 1 1 1 12 11 -1 1 -1 1 1 -1 34 12 1 1 -1 1 -1 -1 60 13 -1 -1 1 1 1 -1 16 14 1 -1 1 1 -1 -1 5 15 -1 1 1 1 -1 1 37 16 1 1 1 1 1 1 52 The observed shrinkage (x10) is shown for the test part produced at each of the 16 runs in the designs. A fractional factorial is analyzed the same as a full factorial. In order to test your understanding of the meaning of the statistical analysis, a Pareto Chart, a mean effects plot, and an interaction plot are included. Study each of these plots and make suggestions concerning the proper levels for each of the parameters so that the shrinkage can be minimized. You must justify each of your parameter settings with information from the plots. You should not do any analysis in Minitab. Everything that you need is provided.BEFBDBFFEAFCDACAEABFADABAB403020100TermEffect2.41A MoldTempB Screw S peedC HoldTimeD C y cleTimeE G ateS izeF HoldPressF actor NamePareto Chart of the Effects(response is ObservedShrinkage, Alpha = 0.05)Lenth's PSE = 0.9375 Mean of ObservedShrinkage1-150403020101-1 1-11-150403020101-1 1-1MoldTemp ScrewSpeed HoldTimeCycleTime GateSize HoldPressMain Effects Plot (data means) for ObservedShrinkageMoldTempMoldTempHoldTimeHoldTimeCycleTimeCycleTimeScrewSpeedScrewSpeed1-1 1-1 1-1604020604020604020MoldTemp-11ScrewSpeed-11HoldTime-11Interaction Plot (data means) for ObservedShrinkage Which factors are significant at a 95% confidence limit? Which interactions are significant at a 95% confidence limit? After analyzing the graphs, complete the table below: Parameter Suggested Setting Reason Mold Temp. Screw Speed Holding Time Cycle Time Gate Size Holding Pressurehttp://commons.wikimedia.org/wiki/File:Gear_pump_exploded.png http://www.britannica.com/EBchecked/topic-art/227609/7032/External-gear-pump 3. (15 points) Consider the gear pump shown above (with more schematic functional drawing above right). The drive shaft turns the drive gear which causes the idler gear to also turn. Oil enters the suction port or inlet and exits the pressure port or outlet (at a higher pressure). a) Create a Subtract and Operate table for two items, the Idler Gear and the Seal. b) State one function (in verb noun form) for the idler gear c) State one function (in verb-noun form) for the seal d) For the System that is the gear pump, sketch and label all the inputs and outputs (indicating Material, Energy, and Signal) Gear Pump4. Does the following “need statement” comply with the guidelines in the textbook? If yes, explain why it complies. If no, explain how it is not in compliance. Customer Statement: I hate it when my backpack bounces when I run. Need Statement: An adjustable sternum strap should be added to the backpack. 5. Write a “need statement” for the following customer statement. Customer Statement: When I’m canoeing and my hands are wet, I can’t keep hold of my backpack zipper. Need Statement: 6. For the following “need statement”, assign a metric (name the units and describe what you will measure. Need Statement: The backpack protects a laptop. Units: What is measured?7. You have met the standard for “competence” to undertake a public works engineering project only if a) You hold an appropriate professional engineering license in that discipline. b) The project outcome will protect the safety, health and welfare of the public. c) You hold a degree in that engineering discipline d) You follow appropriate codes and specifications 8. You are the chief engineer for Boiler Drum Company and have specialized in the design and construction of high pressure steam drums. As a result, you were invited to join the industry’s Boiler and Drum Design Code committee. With the advent of higher pressure steam plants, the industry saw a need to revise the Boiler and