Operations and Supply Chain Management The Core

346 OPERATIONS AND SUPPLY CHAIN MANAGEMENT
Put yourself in the position of a manager at Tesla responsible
for quality and customer satisfaction. What would you
suggest relative to the following questions?
Questions
1. Consumer Reports, the service that reports unbiased
testing and ratings on cars (together with about everything
else we buy), recommends avoiding new cars in
their first year of production, especially those loaded
with new technology. What can Tesla do to refute this
recommendation?
2. How should Tesla “manage” the delivery of the new
Model 3 during the initial production rampup? Think
about this relative to where cars should be delivered
geographically and how the service process should be
designed.
3. Should Tesla deliver cars to customers on a first-come,
first-served basis (i.e., in the order of when deposits
were placed)?
4. What other suggestions would you have for Tesla relative
to ensuring the quality of its new Model 3 car?
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:
1.9 2.0 1.9 1.8 2.2 1.7 2.0 1.9 1.7 1.8
1.8 2.2 2.1 2.2 1.9 1.8 2.1 1.6 1.8 1.6
2.1 2.4 2.2 2.1 2.1 2.0 1.8 1.7 1.9 1.9
2.1 2.0 2.4 1.7 2.2 2.0 1.6 2.0 2.1 2.2
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 C pk for the process?
4. What would be the C pk 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?
PRACTICE EXAM
1. This refers to the inherent value of the product in the
marketplace and is a strategic decision for the firm.
2. Relates to how well a product or service meets design
specifications.
3. Relates to how the customer views quality dimensions
of a product or service.
4. The series of international quality standards.
5. What is the enemy of good quality?
6. A Six Sigma process that is running at the center of its
control limits would expect this defect rate.
7. The standard quality improvement methodology
developed by General Electric.
8. Variation that can be clearly identified and possibly
managed.
9. Variation inherent in the process itself.
10. If a process has a capability index of 1 and is running
normally (centered on the mean), what percentage of
the units would one expect to be defective?
11. An alternative to viewing an item as simply good or
bad due to it falling in or out of the tolerance range.