Download Automation Migration strategy - Computer Integrated Manufacturing - Past Exam and more Exams Computer Integrated Manufacturing in PDF only on Docsity!
Spring Examinations 2008/ 2009
Exam Code(s) 3BI1, 1EM Exam(s) B.E. Degree in Industrial Engineering Erasmus
Module Code(s) IE Module(s) Computer Integrated Manufacturing
Paper No. 1 Repeat Paper
External Examiner(s) Prof. J Antony Internal Examiner(s) Dr. David O’Sullivan Dr. Ke Ning
Instructions: Answer any 5 questions.
All questions will be marked equally.
Duration (^) 3 Hours
No. of Pages Cover + 4 pages Department(s) Industrial Engineering Course Co-ordinator(s) Dr. David O’Sullivan
Requirements: MCQ Handout Statistical Tables Graph Paper Log Graph Paper Other Material
1. Answer each of the following questions in relation to computer integrated
manufacturing and related mathematical models and metrics. Use illustrations and mathematical models to describe your answers throughout.
(a) (i) What is computer integrated manufacturing? (ii) Name five reasons why organizations automate their operations. (iii) What are the three phases of a typical automation migration strategy?
(3 marks each)
(b) The XYZ Company is planning to introduce a new product line and will build a new factory to produce the parts and assembly the final products for the product line. The new product line will include 100 different models. Annual production of each model is expected to be 1000 units. Each product will be assembled of 600 components. All processing of parts and assembly of products will be accomplished in one factory. There are an average of 10 processing steps required to produce each component, and each processing step takes 30 sec. (includes an allowance for setup time and part handling). Each final unit of product takes 3.0 hours to assemble. All processing operations are performed at work cells that each includes a production machine and a human worker. Products are assembled on single workstations consisting of two workers each. If each work cell and each workstation require 20m^2 , and the factory operates one shift (2000 hr/yr), determine: (a) how many production operations, (b) how much floorspace, and (c) how many workers will be required in the plant. (11 marks)
2. Answer each of the following questions in relation to industrial control systems
and hardware for automation and process control. Use illustrations and mathematical models to describe your answers throughout.
(a) (i) What is industrial control? (ii) Name and briefly define each of the three different types of discrete variables. (iii) What are the three functions of adaptive control? (3 marks each)
(b) A DC servomotor has a torque constant = 0.088 N-m/A and a voltage constant = 0.12 V/(rad/sec). The armature resistance is 2.3 ohms. A terminal voltage of 30 V is used to operate the motor. Determine (a) the starting torque generated by the motor just as the voltage is applied, (b) the maximum speed at a torque of zero, and (c) the operating point of the motor when it is connected to a load whose torque characteristic is proportional to speed with a constant of proportionality = 0.011 N-m/(rad/sec).
(11 marks)
Seq. Activity Time 1 Robot reaches and picks part from incoming conveyor and loads into fixture on machine tool.
5.5 sec.
2 Machining cycle (automatic) 33.0 sec. 3 Robot reaches in, retrieves part from machine tool, and deposits it onto outgoing conveyor.
4.8 sec.
4 Move back to pickup position 1.7 sec.
The activities are performed sequentially as listed. Every 30 workparts, the cutting tools in the machine must be changed. This irregular cycle takes 3.0 minutes to accomplish. The uptime efficiency of the robot is 97%; and the uptime efficiency of the machine tool is 98%, not including interruptions for tool changes. These two efficiencies are assumed not to overlap (i.e., if the robot breaks down, the cell will cease to operate, so the machine tool will not have the opportunity to break down; and vice versa). Downtime results from electrical and mechanical malfunctions of the robot, machine tool, and fixture. Determine the hourly production rate. (11 marks)
5. Answer each of the following questions in relation to discrete control using
programmable logic controllers and personal computers. Use illustrations and mathematical models to describe your answers throughout.
(a) (i) Briefly define the two categories of discrete process control? (ii) What is a ladder logic diagram? (iii) What are the five basic components of a PLC? (2 marks each)
(b) An emergency stop system is to be designed for a certain automatic production machine. A single "start" button is used to turn on the power to the machine at the beginning of the day. In addition, there are three ‘stop’ buttons located at different locations around the machine, any one of which can be pressed to immediately turn off power to the machine. (a) Write the truth table for this system. (b) Write the Boolean logic expression for the system. (c) Construct the logic network diagram for the system. (d) Construct the ladder logic diagram for the system. (14 marks)
6. Answer each of the following questions in relation to automated storage systems.
Use illustrations and mathematical models to describe your answers throughout.
(a) (i) Name and briefly describe three of the six measures used to assess the performance of a storage system? (ii) What are some of the objectives and reasons behind company decisions to automate their storage operations?
Question 6 continued overleaf …
(iii) What are the differences between the two basic types of automated storage systems? (3 marks each)
(b) A unit load AS/RS is being designed to store 1000 pallet loads in a distribution centre located next to the factory. Pallet dimensions are: x = 1000 mm, y = 1200 mm; and the maximum height of a unit load = 1300 mm. The following is specified: (1) the AS/RS will consist of two aisles with one S/R machine per aisle, (2) length of the structure should be approximately five times its height, and (3) the rack structure will be built 500 mm above floor level. Using the allowances a = 150 mm, b = 200 mm, and c = 250 mm, determine the width, length, and height of the AS/RS rack structure.
(11 marks)
7. Answer each of the following questions in relation to flexible manufacturing
systems. Use illustrations and mathematical models to describe your answers throughout.
(a) (i) What is a flexible manufacturing system? (ii) Name the four tests of flexibility that a manufacturing system must satisfy in order to be classified as flexible. (iii) What is the difference between the primary and secondary handling systems that are common in flexible manufacturing systems? (2 marks each)
(b) A flexible manufacturing cell consists of two machining workstations plus a load/unload station. The load/unload station is station 1. Station 2 performs milling operations and consists of one server (one CNC milling machine). Station 3 has one server that performs drilling (one CNC drill press). The three stations are connected by a part handling system that has one work carrier. The mean transport time is 2. min. The FMC produces three parts, A, B, and C. The part mix fractions and process routings for the three parts are presented in the table below. The operation frequency fijk = 1.0 for all operations. Determine (a) maximum production rate of the FMC, (b) corresponding production rates of each product, (c) utilization of each machine in the system, and (d) number of busy servers at each station.
Part j Part mix pj Operation k Description Station i Process time tijk A 0.2 1 Load 1 3 min 2 Mill 2 20 min 3 Drill 3 12 min 4 Unload 1 2 min B 0.3 1 Load 1 3 min 2 Mill 2 15 min 3 Drill 3 30 min 4 Unload 1 2 min C 0.5 1 Load 1 3 min 2 Drill 3 14 min 3 Mill 2 22 min 4 Unload 1 2 min
(14 marks)
