Exam 17: Process Improvement Using Control Charts

Among other quality measures,the quality of an electronic component used in manufacturing stereo speakers is monitored with a p chart.In the last 25 days,daily samples of 60 units resulted in the following number of defective units per sample: 8,4,3,7,6,2,5,3,1,0,7,4,2,0,1,6,2,4,3,1,2,8,5,6,0.Determine the center line for this process.

A manufacturer of windows produces one type that has a plastic coating.The specification limits for the plastic coating are 30 and 70.From time to time the plastic coating can become uneven.Therefore,in order to keep the coating as even as possible,thickness measurements are periodically taken at four different locations on the window.15 subgroups were observed,each consisting of four thickness measurements,with the following results: mean of the means = $\overline {\overline{ x } }$ = 50.05,and average range of 8.85.Calculate the control limits for the R chart.

When a process is influenced only by common causes of variation:

A manufacturer of windows produces one type that has a plastic coating.The specification limits for the plastic coating are 30 and 70.From time to time the plastic coating can become uneven.Therefore,to keep the coating as even as possible,thickness measurements are periodically taken at four different locations on the window.15 subgroups were observed,each consisting of four thickness measurements,with the following results: mean of the means = $\overline { \overline { x } }$ = 50.05,and average range of 8.85.Assuming that the process is in statistical control,calculate the natural tolerance limits for the process.

In 20 samples,there are 80 units defective.If each sample consists of 100 units,find the appropriate UCL and the LCL for the p chart.

The distance between natural tolerance limits and customer specifications is called ____________.

From 20 samples of size 100,a total of 80 units are defective.What is the centerline for the p chart?

A foreman wants to use an $\bar { X }$ Chart to control the average length of the bolts manufactured.He has recently collected the six samples given below. Sample 1 1.99 2.01 2.02 2.02 2 2.00 2.00 2.01 2.01 3 1.98 1.99 2.01 1.98 4 2.01 2.02 2.02 1.99 5 1.99 1.99 2.01 1.99 6 2.03 1.98 2.03 2.04 Determine the LCL and the UCL for the R chart.

How well a product or a service performs in the marketplace is called the quality of ______________.

Control charts are used to reduce common causes of variation.

A powder metal manufacturing company is producing sleeves for a locking mechanism.The target (nominal)value for the inside diameter is 1 inch.The inside diameter specifications are 1 ± .005 inches.Assume that the process is in statistical control with $\overline { \overline { X } }$ = 1)0002 inches, $\overline { \mathrm { R } }$ = )003 inches,and subgroup size of 5.Determine the estimated number of standard deviations of process leeway.

Auxiliary lines drawn on a control chart for accomplishing pattern analysis are called ___________ boundaries.

A motorcycle manufacturer produces the parts for its vehicles in different locations and transports them to its plant for assembly.In order to keep the assembly operations running efficiently,it is vital that all parts be within specification limits.One important part used in the assembly is the engine camshaft,and one important quality characteristic is the case hardness depth.Specifications state that the hardness depth must be between 3.0 mm and 6.0 mm.To investigate the process,the quality control engineer selected 25 daily subgroups of n = 5 and measured the hardness depth.The process yielded a mean of the means $\overline { \overline { x } }$ = 4)50 and an average range = 1.01.Find the sigma level capability of the process.

If 20 samples of size 7 are drawn,with $\overline { \overline X }$ = 33.33 and $\bar { R }$ = 5)65,what are the LCL and UCL for the R chart?

A sequence of steadily increasing plot points on a control chart is referred to as ___________.

The number of estimated process standard deviations between $\overline { \mathrm { X } }$ And the closest specification limit is the _____________ of the process.

A control chart on which the proportions of nonconforming units in subgroups of size n are plotted versus time is a(n)_____ chart.

When employing measurement data to study a process,the __________ monitors the process variation.

If $\overline { \overline { X } }$ = 16.1, $\bar { R }$ = )03,and n = 6,and if the specifications are [15.9,16.3],is the process capable?

A motorcycle manufacturer produces the parts for its vehicles in different locations and transports them to its plant for assembly.To keep the assembly operations running efficiently,it is vital that all parts be within specification limits.One important part used in the assembly is the engine camshaft,and one important quality characteristic is the case hardness depth.Specifications state that the hardness depth must be between 3.0 mm and 6.0 mm.To investigate the process,the quality control engineer selected 25 daily subgroups of n = 5 and measured the hardness depth.The process yielded a mean of the means $\overline {\overline{ x } }$ = 4)50 and an average range = 1.01.Calculate the control limits for the R chart.