IET 302 Final Exam

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University of Southern Mississippi *

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302

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Mechanical Engineering

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Jan 9, 2024

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Final Exam IET 302 --- Industrial Quality Control Submission due: December 4 Instruction: Please submit your answers in one single document in the format of either word or excel. Do not submit Minitab file. If you use Minitab, please copy and paste the figures or the screenshots in the word or excel file. Please show your steps for each question in order to receive partial credit. 1 - The data given below are ´ x and R values for 24 samples where each sample includes 5 observations. The data measures the diameter of shock absorber, a mechanical part of vehicle’s suspension system. a) Calculate control limits (LCL, CL, UCL) for ´ x and R charts b) Plot ´ x and R charts. c) Is the process statistically in control? Sample Number ´ x R 1 34.5 3 2 34.2 4 3 31.6 4 4 31.5 4 5 35.0 5 6 34.1 6 7 32.6 4 8 33.8 3 9 34.8 7 10 33.6 8 11 31.9 3 12 34.2 9 13 35.4 8
14 34.0 6 15 37.1 5 16 34.9 7 17 33.5 4 18 31.7 3 19 34.0 8 20 35.1 4 21 33.7 2 22 32.8 1 23 33.5 3 24 34.2 2 (6 pints) 2 - The numbers shown below are inner diameters of piston-rings collected from a manufacturing process. Knowing that the specification range of piston-ring diameter is 30 ± 0.15 mm , then i. Calculate the process capability indices, c p c pk . ii. Analyze the capability of manufacturing process of piston-ring. Do you think the produced piston rings can be used by automotive manufacturers? Observation 1 Observation 2 Observation 3 Observation 4 Observation 5 Sample1 29.98 29.94 30.01 30.06 30.06 Sample 2 30.09 29.89 29.99 30.05 29.95 Sample 3 29.97 29.92 29.91 29.95 29.96 Sample 4 29.89 29.97 29.98 30.01 29.98 Sample 5 29.98 29.98 30.07 30.00 29.99 Sample 6 29.97 30.10 30.04 30.12 29.97 Sample 7 30.01 29.98 30.12 29.96 30.06 Sample 8 30.00 30.00 29.94 29.98 29.99 (6 points)
3 - Which of the following statements is not true? (1 point) a) The philosophy of Pareto chart is that the majority of defective items originate from a few defect types. b) Process capability indices depend on specification limits. c) Moving range is the best way to calculate variability of process when there is only a single observation in each sample. d) In the manufacturing process, expert operators determine the upper and lower control limits of the process. 4 - which phase of six sigma methodology aims to reduce the number of defects (1 point) a) Define b) Measure c) Analyze d) Improve e) Control 5 - Which of the following statement is not true? (1 point) a) Control charts help to examine whether the process is in control or not. b) Control charts determine upper and lower control limits. c) Control charts determine specification limits. d) Upper control limit or UCL is 3 σ greater than center line (CL).
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6 - A quality inspector at a tire manufacturing company has inspected the number of defective tires in 5 samples that are taken randomly with 20 tires in each sample. The number of nonconforming tires in each sample is listed in the table below. Calculate the control limits and plot the control chart. (6 points) Sample No. Number of nonconforming tires 1 3 2 2 3 1 4 2 5 1 7 - Which is the following is not a dimension of quality? (1 point) a) Performance b) Reliability c) Conformance d) cost 8 - Discuss 5 dimensions of quality and give an example for each one. (3 points) 9 - Assume that X is a random number that follows Normal distribution with an average of 5 and variance of 14, calculate a) P ( 2 < X < 6 ) b) P ( X > 7 ) (3 points)
10 - 5 samples have been taken to inspect the quality of tires. In each sample only one observation is made and the stiffness of tires is measured. The data below shows the stiffness of the tire in each sample. Calculates the Moving range (MR) for each sample. (2 points) Sample Observation MR 1 280 ? 2 288 ? 3 295 ? 4 302 ? 5 289 ?