THE ASSIGNMENT IS ATTACHED
ENGG*3070 – Assignment No. 2 (Due Saturday, October 23, 2020 (11:59 pm) Marking: Only selected problems will be marked in detail and the remaining will be checked for completeness and correctness of final answers. The neatness and organization of your assignment report has a significant weight. • The due date for this assignment is extended from Oct 18 to Oct 23. • Moreover, the drobox will remain open for late submission without penalty until October 25, 11:59 PM. • Late submission after the grace period (Oct 25) will not be accepted unless academic consideration is granted. • NOTE: There are a total of 10 problems to be solved, and as such you need to start working on this assignment as early as possible. Problem No. 1 (Manual Assembly Line) A manual assembly line is to be designed to make a small consumer product. The work elements, their times, and precedence constraints are given in the table below. The workers will operate the line for 400 min per day and must produce 300 products per day. A mechanized belt, moving at a speed of 1.25 m/min, will transport the products between stations. Because of the variability in the time required to perform the assembly operations, it has been determined that the tolerance time should be 1.5 times the cycle time of the line. (a) Determine the ideal minimum number of workers on the line. (b) Use the larges candidate rule to balance the line. (c) Use the Kilbridge and Wester method to balance the line. (d) Use the ranked position to balance the line. (e) Compute the balance delay in part (b) (c), and (d). Problem No. 2 (Manual Assembly Line) Two models, A and B, are to be assembled on a mixed-model line. Hourly production rates for the two models are: A, 25 units/hr; and B, 18 units/hr. The work elements, element times, and precedence requirements are given in the table below. Elements 6 and 8 are not required for model A, and elements 4 and 7 are not required for model B. Assume E = 1.0, Er = 1.0, and Mi = 1. (a) Construct the precedence diagram for each model and for both models combined into one diagram. (b) Find the theoretical minimum number of workstations required to achieve the required production rate. (c) Use the Kilbridge and Wester method to solve the line balancing problem. (d) Determine the balance efficiency for your solution . (d) Determine the variable launching internal of each model, and provide a typical variable launching sequence and the time of each launch. (e) Determine the fixed rate launching interval, and the launch sequence of models A and B during for the first 10 launches (Note: the complete answer which you are not required to provide should list a total of 45 launches and can be better done using excel). Problem No. 3 (Manual Assembly Line) Three models A, B, and C are to be assembled on a mixed-model line. Hourly production rates for the three models are: A, 15 units/hr; B, 10 units/hr; and C, 5 units/hr. The work elements, element times, and precedence requirements are given in the table below. Assume E = 1.0, Er = 1.0, and Mi = 1. (a) Construct the precedence diagram for each model and for all three models combined into one diagram. (b) Find the theoretical minimum number of workstations required to achieve the required production rate. (c) Use the Kilbridge and Wester method to solve the line balancing problem. (d) Determine the balance efficiency for the solution. (e) Determine the fixed rate launching interval and the launching sequence of models A, B and C during 1 hour production. Problem No. 5 (Manual Assembly Line) A moving belt line is used to assemble a product whose work content = 22 min. Production rate = 35 units/hr, and the proportion uptime = 0.96. The length of each station = 2.0 m and station manning level = 1.0 for all stations. The belt speed can be set at any value between 0.6 and 3.0 m/min. It is expected that the balance delay will be about 0.08 or slightly higher. Time lost for repositioning each cycle is 6 sec. (a) Determine the number of stations needed on the line. (b) Using a tolerance time that is 50% greater than the cycle time, what would be an appropriate belt speed and spacing between parts?` Problem No. 6 (Transfer Line) A 30-station transfer line has an ideal cycle time of 0.75 min, an average downtime of 6.0 min per line stop occurrence, and a station failure frequency of 0.01 for all stations. A proposal has been submitted to locate a storage buffer between stations 15 and 16 to improve line efficiency. Determine (a) the current line efficiency and production rate, and (b) the maximum possible line efficiency and production rate that would result from installing the storage buffer. Problem No. 7 (Transfer Line) In Problem 6, if the capacity of the proposed storage buffer is to be 20 parts, determine (a) line efficiency, and (b) production rate of the line. Assume that the downtime (Td = 6.0 min) is a constant. Problem No. 8 (Transfer Line) An eight-station rotary indexing machine performs the machining operations shown in the table below, with processing times and breakdown frequencies for each station. Transfer time is 0.15 min. A study of the system was undertaken, during which time 4,000 parts were completed. The study also revealed that when breakdowns occur, the average downtime is 7.5 min. For the study period, determine (a) average hourly production rate, (b) line uptime efficiency, and (c) how many hours were required to produce the 4,000 parts. Station Process Process time Breakdowns 1 Load part 0.50 min 0 2 Mill top 0.85 min 22 3 Mill sides 1.05 min 31 4 Drill two holes 0.60 min 47 5 Ream two holes 0.43 min 8 6 Drill six holes 0.92 min 58 7 Tap six holes 0.75 min 74 8 Unload part 0.40 min 0 Problem No. 9 (Transfer Line) A 16-station transfer line can be divided into two stages by installing a storage buffer between stations 8 and 9. The probability of failure at any station is 0.01. The ideal cycle time is 1.0 min and the downtime per line stop is 10.0 min. These values are applicable for both the one-stage and two-stage configurations. The downtime should be a considered constant value. The cost of installing the storage buffer is a function of its capacity. This cost function is ?? = $0.60?/ hr = $0.01?/min, where ? = the buffer capacity. However, the buffer can only be constructed to store increments of 10 (in other words, ? can take on values of 10, 20, 30, etc.). The cost to operate the line itself is $120/hr. Ignore material and tooling costs. Based on cost per unit of product, determine the buffer capacity ? that will minimize unit product cost. Problem No. 10 (Transfer Line) A proposed synchronous transfer line will have 20 stations and will operate with an ideal cycle time of 0.5 min. All stations are expected to have an equal probability of breakdown, p = 0.01. The average downtime per breakdown is expected to be 5.0 min. An option under consideration is to divide the line into two stages, each stage having 10 stations, with a buffer storage zone between the stages. It has been decided that the storage capacity should be 20 units. The cost to operate the line is $96.00/hr. Installing the storage buffer would increase the line operating cost by $12.00/hr. Ignoring material and tooling costs, determine (a) line efficiency, production rate, and unit cost for the one-stage configuration, and (b) line efficiency, production rate, and unit cost for the optional two-stage configuration (assume a constant repair time).