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Products Software SPCView Program Features Process Control Data Screen

 

SPCView Statistical Process Control Analysis Software from Integrated Sciences Group  SPCView 1.7 - Process Control Data Screen

SPCView Statistical Process Control Software - Process Control Data  Screen

 

Process Control Data Screen Features

The overall functions and features of SPCView are accessed from the Process Control Data screen, which includes a menu bar and activation buttons for quick access to drill-down analysis screens and worksheets, a section containing key information about the subject parameter being analyzed, and a table containing process history data.

 

Menu Bar

The Menu bar provides access to a wide variety of program functions and options including saving and opening analysis files, printing options, editing options, data importing and exporting options, and an option for setting the default date format.

 

Parameter Identification Data

The upper portion of the screen includes parameter identification data, nominal value, estimated parameter value, estimated uncertainty, subject parameter bias, measuring parameter bias, in-tolerance probabilities, sample size, and control limit information.  Data can be entered directly or imported from an UncertaintyAnalyzer file.

 

Control Limit Options

This option allows you to display either the upper and lower control limits  or the upper and lower control offsets.  The upper control offset  is the difference between the upper control limit and the process nominal or mean value. The lower control offset  is the difference between the process nominal or mean value and the lower control limit.  The lower control offset is expressed as a negative number.

 

Control limits (or offsets) can be entered as two-sided asymmetric, two-sided symmetric, single-sided upper, or single-sided lower values.  Control limits can be entered directly in the Upper Control Limit (or Offset) and Lower Control Limit (or Offset) boxes and the associated confidence levels will be computed automatically.  When the option is exercised, the result is shown in the Upper and Lower Control Limit/Offset boxes of the Control Data part of the screen. 

 

Alternatively, the nominal value for a parameter or process, along with the estimated uncertainty from an UncertaintyAnalyzer session, can be used to set control limits for a specified level of confidence.  This second option is done using the Set Control Data button.

 
Process Control Options

There are four process control options to choose from. 

 

  1. Measurement Process

  2. Parameter Value vs. Date

  3. Parameter Interval Analysis

  4. Sampled Process

 

The Measurement Process option concerns the control of the measurement process itself. A measurement process is viewed as consisting of a measuring device or devices, a measuring environment, a measurement procedure and includes human and other perception elements. The option for displaying Control Limits (relative to the Nominal Value) is disabled and only Control Offsets are enabled.  This is because the Control "Limits" plotted on the Control Chart are bounding limits for deviations between measured check standard values and a priori assumed values -- not deviations from nominal. This is necessary because the check standard assumed value may change from control point to control point.
 
The Parameter Value vs. Date option focuses on parameter as the subject of control rather than the  process that measures it.  The parameter being measured is assumed to drift or change in value over time.  This option involves keeping a running history of the value of a parameter (or the parameter's deviation from nominal) over time. 
 

The Parameter Interval Analysis option also assumes that the value of a measured parameter changes from measurement date to measurement date.  For  many parameters, the longer the interval between measurements, the greater the change (on  average). The usual parameter data are entered in the process control history table along with "as-found" and "as-left" values for each control point.

 
The Sampled Process option applies statistical process control to the output of a manufacturing or other output process and not the measuring system.  The process is controlled by (1) measuring the value of a parameter characterizing the process output, (2) entering the measured value, together with measurement uncertainties, in a process control timeline and (3) evaluating the process statistically. 

 

Process Control Histories 
In controlling a measurement process, monitoring the drift in a parameter value, or monitoring the output of a process, measurements are made at various times to obtain a "process control history."  The history for a selected process is stored in the Control History Data table located on the bottom portion of the screen.  Each row of the table contains a process control record comprised of the measured value of the parameter or process of interest, the uncertainty in the measurement, the date of measurement, process sample size, and other relevant information.

 

Measurement data and uncertainty analysis results obtained from UncertaintyAnalyzer can be imported directly into the Control Data History table by clicking the Update Record button. A record update can be undone by clicking the Undo Update button.  Data can also be imported from an external application via the Run External Application screen, copied and pasted from the Windows clipboard or manually entered in the table.  Records can be deleted by clicking on any cell in the desired row and selecting the Delete Row option from the Edit menu.

 

Once enough process control history is assembled for  plotting (greater than or equal to three points), a control chart can be generated by clicking the View Chart button, which activates the Process Control Chart Screen.

 

 

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Integrated Sciences Group
14608 Casitas Canyon Road Bakersfield, CA 93306
Phone 1-661-872-1683 FAX 1-661-872-3669

 

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Page Updated February 12, 2015