hw09
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University of California, Los Angeles *
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183A
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Aerospace Engineering
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Dec 6, 2023
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5
Uploaded by GrandLemurMaster943
MAE 183A: Spring Quarter 2023 Last Name First Name Page 1 of 1 Homework Assignment #09: Due Thursday, June 08, 2023 Multiple Choice: MC37.1: Human resources are never required in a fully automated manufacturing system: (a) true or (b) false MC37.2: Process parameters are inputs to a process, whereas process variables are outputs of a process: (a) true or (b) false MC37.3: Which of these work situations promote the use of robots in place of human workers: (a) frequent job changeovers, (b) hazardous work environment, (c) repetitive work cycle, (d) multiple work shifts, (e) task requires mobility MC38.1: Fixed routing is associated with which manufacturing systems? (a) automated production lines, (b) automated storage systems, (c) cellular manufacturing systems, (d) flexible manufacturing systems, (e) job shops, (f) manual assembly lines MC38.2: Repositioning time on a manual assembly line is defined as: (a) lost time each cycle on a mixed-model line due to differences between models, (b) lost time each cycle to reposition the worker, the work unit, or both, (c) time between batches in a batch-
model line, (d) time to relocate workstations on a batch- model line to prepare for the next product MC38.3: Parts classification and coding systems are based on which part attributes? (a) annual production rate, (b) date of design, (c) design, (d) manufacturing, (e) weight MC39.1: Which of the following are usual responsibilities of the manufacturing engineering department? (a) advising on design for manufacturability, (b) facilities planning, (c) marketing the product, (d) plant management, (e) process improvement, (f) process planning, (g) product design, (h) solving technical problems in the production departments, (i) supervision of production workers MC39.2: In a sequence of manufacturing processes used to produce a part, a basic process establishes the final geometry of the part, whereas secondary processes are used to enhance properties and provide coatings (e.g., painting or plating) on the part surface: (a) true or (b) false MC39.3: In lean production, which principles and objectives are associated with worker involvement (a) continuous improvement, (b) error prevention, (c) just-in-time, (d) standard work procedures, (e) total productive maintenance, (f) visual management MC40.1: Which of the following quality aspects would be classified as examples of freedom from deficiencies rather than product features? (a) components within tolerance, (b) location of ON/OFF switch, (c) no missing parts, (d) product weight, (e) reliability, (f) reputation of the company MC40.2: A control chart is a graphical technique in which statistics computed from measured values of a certain process characteristic are plotted over time to determine if the process remains in statistical control: (a) true or (b) false MC40.3: Which process capability index value will result in a greater proportion of out-of-tolerance parts? (a) 0.667, (b) 1.000, (b) 1.333 Review Questions: Chapter 37: 37.3, 37.20, 37.23 Chapter 38: 38.10, 38.17, 38.20 Chapter 39: 39.2, 39.10, 39.27 Chapter 40: 40.3, 40.14, 40.19 Problems: Chapter 37: 37.2, 37.14, 37.17 Chapter 38: 38.3, 38.9, 38.13 Chapter 40: 40.3, 40.6, 40.14, 40.18
HW 9 Review Questions 37.3 What is the difference between a closed-loop control system and an open-loop control system? The difference between a closed-loop control system and an open-loop control system is that a closed-loop control system incorporates sensors that give feedback for the system to be compared and the controller can be adjusted. 37.20 Under what circumstances is a closed-loop positioning system preferable to an open-loop system? A closed-loop positioning system is preferable to an open-loop system when there are significant reaction forces resisting motion. 37.23 What is control resolution in the operation of a positioning system? Control resolution is the distance that separates two adjacent control points in the axis movement. 38.10 What are two practical reasons why the minimum number of workers wmin given by the minimum integer ≥
Twc/Tc cannot be achieved on a manual assembly line, where Twc = work content time and Tc = cycle time? One practical reason is imperfect balancing is when some workers assigned an amount of work will take less time than Tc. Another practical reason is repositioning losses which is where some time is lost at each station to reposition the work or worker cycle. 38.17 What are some of the reasons for downtime on a machining transfer line? Some of the reasons for downtime on a machining transfer line is scheduled and/or unscheduled tool changes, mechanical and electrical malfunctions, hydraulic failures, and normal equipment wear. 38.20 What is the composite part concept in group technology? A composite part concept is a hypothetical part that includes all the design and manufacturing attributes of the family. 39.2 What is included within the scope of process planning? Process planning includes deciding what processes and methods should be used and in what order, determining tooling requirements, selecting production equipment and systems, and estimating costs of production for the chosen processes, tooling, and equipment.
39.10 Identify some important factors that should enter into the make or buy decision. Cost is the most important factor in the make or buy decision. Other important factors are process available in-house, production quantity, product life, standard items, supplier reliability, and alternative source. 39.27 How is a pull system distinguished from a push system in production and inventory control? A pull system of production control is when the order to produce parts at a given workstation comes from the downstream station that uses those parts. A push system of production operates by supplying parts to each station in the plant, in effect driving the work from upstream stations to downstream stations. 40.3 What are the natural tolerance limits? The upper and lower boundaries of tolerance when they are set to the process capability are defined as +/- 3 standard deviations from the mean. 40.14 How does quality control testing differ from quality control inspection? Quality control testing refers to subjecting the part to certain conditions that might be expected in service and observing its response to determine its performance level. Quality control refers to measurement and gaging techniques to determine whether a product meets specifications. 40.19 What are the three steps in the operation of a machine vision system? Briefly describe them. Image acquisition and digitizing is done through a video camera connected to a digitizing system that stores the image data for post processing. Image processing and analysis detects features that are in an image with a variety of methods including edge detection and identifying contrast in light intensity. Once the features are identified, the area of the object can be counted by tracking the number of pixels. Interpretation is where one wants to identify what the object is. A common technique is template matching which compares the features in the image to existing models.
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