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Multiple Cpk Charts Help

SPC for Excel can make multiple Cpk charts at one time. This page shows you how to make a multiple Cpk charts using the data that can be downloadedat this link. Once each chart is made, it is handled like a Cpk chart made individually. This page contains the following:

The options listed for the multiple Cpk charts are the same as for the Cpk chart. Please refer to the help for Cpk Charts for information on those options and updating/changing options.

Data Entry

The data are entered into a worksheet as shown below (using the first part of the data into the example workbook). The data can be anywhere on the spreadsheet, but with the Multiple Cpk, the data must be in columns (one column for each set of data). In this example, there are four machines and we want to create a Cpk chart for each machine.

There must be a row for the chart names. These are the names of the charts that will appear on the worksheet tabs containing the chart. These names must be unique to the workbook and meet the requirements for naming a worksheet tab in Excel (maximum length, no characters such as “/”). There must be a name for each chart. In this example, the names are Machine 1, Machine 2, etc.

The data in the column under each chart name applies to that chart. The additional rows include LSL, Nominal, USL and Target. Only one specification is required. Under Machine 1, the LSL = 70, Nominal = 100, USL = 130, and Target = 105. If the target is entered, the value of Cpm is calculated. The data for the Cpk analysis are then listed in the column for that the machine.

Creating a Multiple Cpk Charts

Options for Multiple Cpk Charts

If you select “Show Options” on the input screen above, the input display is changed to the following:

The four options are identical to those for the Cpk chart. Please refer to the Cpk chart options for details.

Options after Multiple Cpk Charts are Made

After the multiple Cpk charts are made, each is treated as single Cpk chart. See the Cpk Chart help page for the following:

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