MECH 3170 Assignment #1 This assignment covers material from Chapters 1, 5, and 6 of Operations and Supply Chain Management by Jacobs and Chase (13th Edition) from your reading package as well as topics discussed in class and tutorials. Instructions:
Please answer all questions. You are welcome to work with fellow students on the assignment, however, each student is required to submit their own hard copy assignment for grading. If you work with others, please list their names on your assignment. Assignment #1 is worth 1% of your final grade in the course. Assignment #1 is due on Monday, January 26, 2015 before 8:30 am (in class).
Questions: 1) Using Exhibit 1.3 (from Chapter 1 of Jacobs and Chase, 13th Edition) as a model, describe the source‐make‐deliver‐return relationships (i.e. what types of organizations might be included in each of these categories) in the following systems: a. An airline b. An automobile manufacturer c. A hospital d. An insurance company 2) An engineering university team is about to manufacture control arms for a Formula (or electric) SAE vehicle. There are 5 students working on the manufacturing and they will be arranged with 1 student per a station for the entire process. All students will begin at the exact same time. Please assume that no buffers exist (buffers are not allowed). One batch of parts consists of 8 complete parts and only one batch will be produced. The process consists of the following steps and predicted average task times per unit: Task
a) Manufacture spherical bearing housings using a lathe b) Cut Chromoly tubes to length c) Notch tube ends d) Assemble on jig and perform final tuning of fit (includes 3 bearing housings and 2 prepared tubes per a finished part) e) Weld assembled components on second jig
Prerequisite
None None parts from b 3 parts from a 2 parts from b Parts from d
Required Time / Unit 20 min. 1 min. 3 min. 10 min. 10 min.
a) b) c) d) e) f) g) h) i)
Draw the process flowchart. Is there a bottleneck and if so, which station is the bottleneck? Would any station(s) be subject to blocking and if so which station(s)? Would any station(s) be subject to starving and if so which station(s)? What is the cycle time? What is the throughput rate? What is the operation time for 1 complete batch? What is the utilization of Station b? Last year’s team manufactured control arms with a cycle time of 45 minutes, what is this year’s team’s efficiency compared to last year’s team? j) Assume that a buffer is added after station a. If the student at station a were to begin before the other students, how early (at a minimum), should this student begin in order to maximize the utilization of the welding equipment?
3) Hipit is a biomedical company which manufactures custom total hip replacement stems based on patient MRI data. The company combines each of their stems with a head‐cup assembly from a single supplier. It takes 5 hours to make a total hip replacement and the company ships an average of 40 total hip replacements each 8 hour shift. Hipit holds an average inventory level of 500 head‐cup assemblies as raw materials. How many head and cup assemblies are in the plant (raw materials and work in progress)? 4) The Goodparts Company produces a component that is subsequently used in the aerospace industry. The component consists of three parts (A, B, and C) that are purchased from outside and cost 40, 35, and 15 cents per piece, respectively. Parts A and B are assembled first on assembly line 1, which produces 140 components per hour. Part C undergoes a drilling operation before being finally assembled with the output from assembly line 1. There are in total six drilling machines, but at present only three of them are operational. Each drilling machine drills part C at a rate of 50 parts per hour. In the final assembly, the output from assembly line 1 is assembled with the drilled part C. The final assembly line produces at a rate of 160 components per hour. At present, components are produced eight hours a day and five days a week. Management believes that if need arises, it can add a second shift of eight hours for the assembly lines. The cost of assembly labour is 30 cents per part for each assembly line; the cost of drilling labour is 15 cents per part. For drilling, the cost of electricity is 1 cent per part. The total overhead cost has been calculated as $1,200 per week. The depreciation cost for equipment has been calculated as $30 per week.
a. Draw a process flow diagram and determine the process capacity (number of components produced per week) of the entire process. b. Suppose a second shift of eight hours is run for assembly line 1 and the same is done for the final assembly line. In addition, four of the six drilling machines are made operational. The drilling machines, however, operate for just eight hours a day. What is the new process capacity (number of components produced per week)? Which of the three operations limits the capacity? c. Management decides to run a second shift of eight hours for assembly line 1 plus a second shift of only four hours for the final assembly line. Five of the six drilling machines operate for eight hours a day. What is the new capacity? Which of the three operations limits the capacity? d. Determine the cost per unit output for questions b. and c. e. The product is sold at $4.00 per unit. Assume that the cost of a drilling machine (fixed cost) is $30,000 and the company produces 8,000 units per week. Assume that four drilling machines are used for production. If the company had an option to buy the same part at $3.00 per unit, what would be the break‐even number of units? 5) A firm is selling two products, chairs and bar stools, each at $50 per unit. Chairs have a variable cost of $24, and bar stools, $20. Fixed costs for the firm is $20,000. a. If the sales mix is 1:1 (one chair sold for every bar stool sold), what is the break‐even point in dollars of sales? In units of chairs and bar stools? b. If the sales mix changes to 1:4 (one chair sold for every four bar stools sold), what is the break‐even point in dollars of sales? In units of chairs and bar stools?
