Exam 24: Quality Control

A manufacturer of a particular grade of copper tubing collects data on the number of flaws occurring in 500 foot coils. Suppose they sample a total of 40 coils to initiate control charting. The average number of defects per coil is 2.5. The lower and upper control limits for the appropriate control chart for these data are

A producer of specialty products uses a variety of natural and man-made materials to make unique countertops for kitchens and baths. One product line mixes concrete and natural river stone to make countertops that are polished to a high shine revealing unique patterns. Occasionally coarse sand will result in undesirable pitting and rough spots on surfaces. Consequently, as part of its quality control efforts, 8 by 4 foot polished slabs are checked periodically for imperfections. For each slab inspected the number of imperfections (pits, rough spots, etc.) is recorded. a. What type of control chart should be used for these data? b. If the average number of imperfections per 8 by 4 foot polished slab is 2.6, calculate the centreline and control limits for the appropriate control chart.

An importer of decorative ceramic tile samples 50 tiles each day from incoming shipments. Some tiles are cracked or broken before or during transit, rendering them useless scrap. Sampling from incoming shipments for 30 days reveals that a total of 250 tiles are cracked or broken. The lower and upper control limits on the p chart for these data are

An importer of decorative ceramic tile samples 50 tiles each day from incoming shipments. Some tiles are cracked or broken before or during transit, rendering them useless scrap. Sampling from incoming shipments for 30 days reveals that a total of 250 tiles are cracked or broken. The centreline on the p chart for these data is

Consider the following to answer the question(s) below: A company that fills 12 ounce soft drink bottles wishes to monitor the quality of their process. To do this, the company has taken a series of samples of 4 bottles. The overall average fill is 12.03 ounces. The average range for the samples has been 0.06 ounces. -What is the correct estimated process standard deviation ( )?

Consider the following to answer the question(s) below: A company that fills 12 ounce soft drink bottles wishes to monitor the quality of their process. To do this, the company has taken a series of samples of 4 bottles. The overall average fill is 12.03 ounces. The average range for the samples has been 0.06 ounces. -Based on this information, what is the value of the upper control limit for the R chart?

Machine oil is used by clothing manufacturers to lubricate and protect sewing machines. A company that produces machine oil must ensure that the viscosity of its product meets customer requirements. Consequently, the viscosity of every batch of oil produced is measured. Suppose that the process mean is 101 cP and the process standard deviation is 1.50 cP. a. What type of chart should be used to ensure the process remains in control? b. Determine the centreline and control limits for this chart. c. Suppose that customer specifications require viscosity of the machine oil to be 100 cP ± 4.5 cP (i.e., the LSL = 95.5 cP and the USL = 104.5 cP). Calculate and interpret both the Cp and Cpk indices.

Recently a shipping company took 30 samples of the delivery times of packages that it was responsible for. Each sample was of 100 packages. Out of the 3,000 total packages, 300 were delivered late. In setting up a process control chart, what would be the correct upper control limit for the appropriate control chart for these data?