Cylinder Liner Boring Case Study
Cylinder Liner Boring Case Study
Introduction
The cylinder liner boring case study demonstrates the use and application of X bar and R charts in manufacturing. The use of these control charts help in identification of both sporadic and chronic faults in the process, and help to formulate improvement actions.
A supplier to an engine manufacturer produces cast iron cylinder liners. Due to a recent management change, the supplier is initiating a companywide quality improvement strategy. A vertically and horizontally study team was formed to identify sources of variation in the process of the cylinder liner production. The first action performed by this team was to conduct a flow chart of the cylinder liner production. After the flow chart for the manufacturing process was completed, the new specifications were applied to the subset of historical data. A Pareto chart was prepared that showed the defect data when the new specifications were applied. By examining the Pareto chart, out-of-spec liner inside diameter was shown to be the most sensitive to the planned change in specification. The focus of the group shifted to drawing a cause-and-effect diagram, summarizing the collective knowledge relative to the potential root causes for out-of-spec inner diameter liner.
Data Collection #1
Data was collected to assess the stability of the boring process. A sample of size n = 5, was taken every 25 minutes, for a total of 40 separate samples throughout the day. For each sample, the sample mean and sample range was calculated. The grand average and the average range were calculated to be 200.25” and 7.60” respectively. For the X bar chart the upper control limit (UCL) and lower control limit (LCL) were calculated to be 204.64” and 195.86” respectively. The R chart UCL and LCL were 16.07” and 0” respectively.
When examining the X bar and R charts, it is important to examine the R chart first. By examining the R chart for the initial sample set it showed that
Introduction
The cylinder liner boring case study demonstrates the use and application of X bar and R charts in manufacturing. The use of these control charts help in identification of both sporadic and chronic faults in the process, and help to formulate improvement actions.
A supplier to an engine manufacturer produces cast iron cylinder liners. Due to a recent management change, the supplier is initiating a companywide quality improvement strategy. A vertically and horizontally study team was formed to identify sources of variation in the process of the cylinder liner production. The first action performed by this team was to conduct a flow chart of the cylinder liner production. After the flow chart for the manufacturing process was completed, the new specifications were applied to the subset of historical data. A Pareto chart was prepared that showed the defect data when the new specifications were applied. By examining the Pareto chart, out-of-spec liner inside diameter was shown to be the most sensitive to the planned change in specification. The focus of the group shifted to drawing a cause-and-effect diagram, summarizing the collective knowledge relative to the potential root causes for out-of-spec inner diameter liner.
Data Collection #1
Data was collected to assess the stability of the boring process. A sample of size n = 5, was taken every 25 minutes, for a total of 40 separate samples throughout the day. For each sample, the sample mean and sample range was calculated. The grand average and the average range were calculated to be 200.25” and 7.60” respectively. For the X bar chart the upper control limit (UCL) and lower control limit (LCL) were calculated to be 204.64” and 195.86” respectively. The R chart UCL and LCL were 16.07” and 0” respectively.
When examining the X bar and R charts, it is important to examine the R chart first. By examining the R chart for the initial sample set it showed that