Managing for Quality and Performance Excellence 10th Edition by James Evans ,William Lindsay

Exercise 5

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
An automated production system at Autosys Inc. consists of three operations: turning, milling, and grinding. Individual parts are transferred from one operation to the next by a robot. Hence, if one machine or the robot fails, the process stops. A production analyst has found that the failure rates for each machine can be described by an exponential distribution.
a. If the failure rates of the robot, turning center, milling machine, and grinder are 0.006, 0.004, 0.002, and 0.001, respectively, what is the reliability of the system for 120 hours of operation?
b. Suppose that the critical machine is found to be the grinder. If four grinders are available (in parallel), with the failure rate of 0.001 each, what is the reliability of the grinder subsystem for 120 hours of operation?