Exam 7: Statistical Process Control

The specifications for a manifold gasket that installs between two engine parts calls for a thickness of 2.500 mm ± .020 mm. The standard deviation of the process is estimated to be 0.004 mm. What are the upper and lower specification limits for this product? The process is currently operating at a mean thickness of 2.50 mm. (a) What is the Cp for this process? (b) About what percent of all units of this liner will meet specifications? Does this meet the technical definition of Six Sigma?

The __________ is the percent defective in an average lot of goods inspected through acceptance sampling.

Producer's risk is the probability of

Which of the following is true of a p-chart?

A run test is used

A c-chart is appropriate to plot the number of flaws in a bolt of fabric.

What is the difference between the process capability ratio Cp and the process capability index Cpk?

A part that connects two levels should have a distance between the two holes of 4". It has been determined that x-bar and R-charts should be set up to determine if the process is in statistical control. The following ten samples of size four were collected. Calculate the control limits, plot the control charts, and determine if the process is in control. Mean Range Sample 1 4.01 0.04 Sample 2 3.98 0.06 Sample 3 4.00 0.02 Sample 4 3.90 0.05 Sample 5 4.03 0.06 Sample 6 3.97 0.02 Sample 7 4.02 0.02 Sample 8 3.99 0.04 Sample 9 3.98 0.05 Sample 10 4.01 0.06

A Cp of 1.33 indicates how many sigma limits

A Type II error occurs when

A consultant has been brought in to a manufacturing plant to help apply six sigma principles. Her first task is to work on the production of rubber balls. The upper and lower spec limits are 21 and 19 cm respectively. The consultant takes ten samples of size five and computes the sample standard deviation to be .7 cm and the sample mean to be 19.89 cm. Compute Cp and Cpk for the process. Give the consultant advice on what to do with the process based on your findings.

The __________ is the chief way to control attributes.

Averages of small samples, not individual measurements, are generally used in statistical process control.

A quality analyst wants to construct a sample mean chart for controlling a packaging process. He knows from past experience that the process standard deviation is two ounces. Each day last week, he randomly selected four packages and weighed each. The data from that activity appears below. $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\text { Weight }$ Day Package 1 Package 2 Package 3 Package 4 Monday 23 22 23 24 Tuesday 23 21 19 21 Wednesday 20 19 20 21 Thursday 18 19 20 19 Friday 18 20 22 20 (a) Calculate all sample means and the mean of all sample means. (b) Calculate upper and lower control limits that allow for natural variations. (c) Is this process in control?

The normal application of a p-chart is in

The width of a bronze bar is intended to be one-eighth of an inch (0.125 inches). Inspection samples contain five bars each. The average range of these samples is 0.01 inches. What are the upper and lower control limits for the x-bar and R-chart for this process, using 3-sigma limits?

Statistical process control charts

What are the three possible results (or findings) from the use of control charts?

A process is operating in such a manner that the mean of the process is exactly on the lower specification limit. What must be true about the two measures of capability for this process?

An acceptance sampling plan is to be designed to meet the organization's targets for product quality and risk levels. Which of the following is true?