Lecture 8.pdf - LECTURE 8 PROCESS CONTROL-II TEXTBOOK CHAPTER 7 INSE 6210 1 CONSTRUCTING CONTROL CHARTS Steps in constructing control charts Preparation

Lecture 8.pdf - LECTURE 8 PROCESS CONTROL-II TEXTBOOK...

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L E C T U R E 8 : P R O C E S S C O N T R O L - I I T E X T B O O K C H A P T E R 7 1 INSE 6210
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CONSTRUCTING CONTROL CHARTS Steps in constructing control charts Preparation of data Choose the variable or attribute to be measured. Determine the basis, size, and frequency of sampling. Setup the control chart. Data collection Record the data. Calculate relevant statistics: averages, ranges, proportions, and so on. Plot the statistics on the chart. Determination of trial control limits Draw the center line(process average) on the chart. Compute the upper and lower control limits. Analysis and interpretation Investigate the chart for lack of control Eliminate out-of-control points Re-compute control limits if necessary Use as a problem solving tool Continue data collection and plotting Identify out-of-control situations and take corrective action. Determination of process capability using the control chart data 2
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CONTROL CHARTS FOR VARIABLE DATA Commonly used control charts for variable data are the x-bar and R- chart. The x-bar chart is used to monitor the centering of the process (mean) and the R-chart is used to monitor the variation of the process (range). 3
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