Production & Operations Management page 350

Tesla Case study PART B ONLY Questions 1-8 (all)

Case Part A: Tesla's Quality Challenge_ that lets a driver park and retrieve their car with no one When Tesla announced the release of its new Model 3 elec- inside. Many post-production issues have been addressed tric car, over 276,000 people from around the world put down through software updates downloaded to customers over $1,000 reservations for the car within three days. The inno- wireless connections. Other mechanical problems are more vative new car is a follow-up to the much more expensive difficult to resolve. Model S and Model X cars. Tesla, led by Elon Musk, the Owners have complained that the Model X falcon-wing brilliant CEO of the company, now sells over 500,000 cars doors will not open. When owners have problems like this, a year. The company will soon introduce the Cybertruck. Tesla typically schedules a time to pick up the car for repair and leaves a loaner for use by the customer. The fledgling Palo Alto, California, automaker has strug-_ Another recent issue was a latch on the third-row seat gled with ramping up manufacturing when new vehicles are to recall 2,700 undone during a collision. Tesla decided introduced. Consider the problems that Tesla had with the new design. Ti Model X cars to replace the latches with a Model X sport utility vehicle when it was introduced. The outlets with waits of totally overloaded Tesla's service company reported that there were many sourcing changes repair. Some customers wan two weeks to make the made late in the process of planning production. Tesla tends long wait. to make items, such as the middle seats in the Model X, in- So far, customers expect the "white-glove" treatment that house rather than outsourcing them, which is done by many Tesla currently offers, but a big concern is what Tesla will do when there are millions of vehicles on the road. Mr. Musk's The issues associated with the production of the cars Tesla cars have many loyal customers, even though problems are a complex combination of mechanical and computer have been encountered. But moving from hundreds of thousoftware problems. Popular features of the cars include sands of vehicles to millions may be difficult, unless some driving-assist autopilot functions, auto-parallel parking, and major service improvements are made. auto-braking. The cars even have an auto-summons feature Case Part B: Quality Control Analytics As part of the process for improving the quality of their cars, engineers have identified a potential improvement to the process that makes a washer that is used in the accelerator assembly. The tolerances on the thickness of the washer are fairly large since the fit can be loose, but if it does happen to get too large, it can cause the accelerator to bind and create a potential problem for the driver. (Note: This part of the case has been fabricated for teaching purposes.) Let's assume that as a first step to improving the process, a sample of 40 washers coming from the machine that produces the washers was taken and the thickness measured in millimeters. The following table has the measurements from the sample: Questions 1. If the specification is such that no washer should be greater than 2.4 millimeters, assuming that the thicknesses are distributed normally, what fraction of the output is expected to be greater than this thickness? 2. If there are upper and lower specifications, where the upper thickness limit is 2.4 and the lower thickness limit is 1.4, what fraction of the output is expected to be out of tolerance? 3. What is the Cph for the process? 4. What would be the Cp for the process if it were centered between the specification limits (assume the process standard deviation is the same)? 5. What percentage of output would be expected to be out of tolerance if the process were centered? 6. Set up X and range control charts for the current process. Assume the operators will take samples of 10 washers at a time. 7. Plot the data on your control charts. Does the current process appear to be in control? 8. If the process could be improved so that the standard deviation were only about 0.10 millimeter, what would be the best that could be expected with the processes relative to the fraction defective