Exam 19: 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.The process is currently operating at a mean thickness of 2.50 mm.(a)What are the upper and lower specification limits for this product? (b)What is the Cp for this process? (c)About what percent of all units of this gasket will meet specifications? Does this meet the technical definition of Six Sigma?

A manufacturer uses statistical process control to control the quality of the firm's products.Samples of 50 of Product A are taken,and a defective/acceptable decision is made on each unit sampled.For Product B,the number of flaws per unit is counted.What type(s)of control charts should be used?

The higher the process capability ratio,the greater the likelihood that process will be within design specifications.

Mistakes stemming from workers' inadequate training represent an assignable cause of variation.

What do the terms producer's risk and consumer's risk mean?

Natural variations:

What is the statistical process chart used to control the number of defects per unit of output?

An acceptance sampling plan's ability to discriminate between low quality lots and high quality lots is described by:

Jars of pickles are sampled and weighed.Sample measures are plotted on control charts.The ideal weight should be precisely 11 oz.Which type of chart(s)would you recommend?

A nationwide parcel delivery service keeps track of the number of late deliveries (more than 30 minutes past the time promised to clients)per day.They plan on using a control chart to plot their results.Which type of control chart(s)would you recommend?

A process that is in statistical control will always yield products that meet their design specifications.

The upper and lower limits for diving ring diameters made by John's Swimming Co.are 40 and 39 cm. ,respectively.John took 11 samples with the following average diameters (39,39.1,39.2,39.3,39.4,39.5 39.6,39.7,39.8,39.9,40).Is the process in control?

A manager wants to build 3-sigma x-bar control limits for a process.The target value for the mean of the process is 10 units,and the standard deviation of the process is 6.If samples of size 9 are to be taken,what will be the upper and lower control limits,respectively?

The ________ is the percentage defective in an average lot of goods inspected through acceptance sampling.

A process is said to be in statistical control when assignable causes are the only sources of variation.

Which of the following statements about acceptance sampling is TRUE?

The specification for a plastic handle calls for a length of 6.0 inches ± .2 inches.The standard deviation of the process is estimated to be 0.05 inches.What are the upper and lower specification limits for this product? The process is known to operate at a mean thickness of 6.1 inches.What are the Cp and Cpk values for this process? Is this process capable of producing the desired part?

Statistical process control charts:

Cartons of Plaster of Paris are supposed to weigh exactly 32 oz.Inspectors want to develop process control charts.They take ten samples of six boxes each and weigh them.Based on the following data,compute the lower and upper control limits and determine whether the process is in control.

Larry's boat shop wants to monitor the number of blemishes in the paint of each boat.Construct a 3-sigma c-chart to determine if their paint process is in control using the following data.