Exam 17: Process Improvement Using Control Charts

In a manufacturing process,if the limits for a control chart are set too _____________,the risk of unnecessarily tampering with the process ____________.

When using and R charts to analyze and improve a process,first,the chart is analyzed and the necessary action(s)to correct assignable causes of variation is (are)taken before the R chart is analyzed.

How well a process is able to meet the requirements set forth by the process design is called the quality of _____________.

A range chart is a control chart in which ranges between individual process measurements within subgroup are plotted.

A motorcycle manufacturer produces the parts for its vehicles in different locations and transports them to it 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 = 4.50 and an average range = 1.01. Calculate the control limits for the R chart.

Periodic sampling is observing the output of a process at random intervals.

A motorcycle manufacturer produces the parts for its vehicles in different locations and transports them to it 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 = 4.50 and an average range = 1.01. How many standard deviations of leeway exist between x and the specification closest to x?

Control charts are used to reduce 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,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 and each subgroup consists of the four thickness measurements taken across the windows at a particular time with the following results: mean of the means = = 50.05 and the average range of 8.85. Find the sigma level capability of the process.

A p-chart is a control chart on which the proportions of nonconforming units are plotted versus time.

A fastener company produces a certain type of bolt for the automobile industry with a nominal (target)length of 2.00 inches.The specifications for the length of the bolt are 2.00 $\pm$ .006 inches.An automobile manufacturing company will only purchase from this company if the sigma level of capability of the process is at least 4.If the process mean is equal to 2.001,determine the maximum process standard deviation necessary for the fastener manufacturing company in order to qualify as a supplier for the automobile manufacturing company.

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 $\pm$ .005 inches.Assume that the process is in statistical control with = 1.0002 inches, = .003 inches and subgroup size of 5. Determine the estimated number of standard deviations of process leeway.

Consider two processes.Process 1's mean is equal to its target (nominal)value,while the process 2's mean is not equal to its target value.The Cpkvalue for process 1 will _____,Cpkvalue for process 2.

A fastener company produces bolts with a nominal (target)length of 2.00 inches.The specifications are 2.00 $\pm$ .006 inches. If the process mean is 2.001 and the process standard deviation is .0016,determine the estimated standard deviations of leeway for this process.

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 $\pm$ .005 inches.Assume that the process is in statistical control with = 1.0002 inches, = .003 inches and subgroup size of 5. Calculate the estimated proportion of out of specification sleeve inside diameters.

The quality of an electronic component used in manufacturing cell phones is monitored with a p-chart.In the last 20 days daily samples of 75 units resulted in the following number of defective units per sample: 8,4,3,7,3,1,0,7,4,2,0,1,6,2,4,3,1,2,8,5 Find the LCL and UCL for the p-chart

Among other quality measures,the quality of an electronic component used in manufacturing stereo speakers is monitored with a control chart.In the last 25 days daily samples 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,and 0.Determine the appropriate upper and lower control limits for this process.

Unusual sources of process variation that can be attributed to specific reasons are called _____ causes of variation.

For a given control chart,zone boundaries consist of UCL and LCL.

Suppose that and R charts are based on subgroups of size four are being used to monitor the tire diameter size of a new radial tire manufactured by a tire company.The and R charts are found to be in statistical control with inches.A histogram of the tire diameter measurements indicates that distribution of these measurements is approximately normally distributed.Compute the natural tolerance limits for this process.