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In the 27th Minitab tutorial, we will accompany the quality team of Smartboard Company as they analyze the process capability of the die casting process for the production of skateboard axles as part of a quality improvement process. Before we get into the actual process capability analysis, we will first see which work steps are required in advance. We will see how the quality team uses the probability plot, and the associated Anderson- Darling test, to work out whether the sample data set available for the process capability follows the laws of normal distribution. We will learn how to use appropriate quality control charts to check whether the die casting process provides the necessary process stability, in the run-up to the actual process capability analysis. The core of this Minitab tutorial will be to get to know all relevant capability indicators within the framework of the process capability analysis, which relate to the overall process capability on the one hand, and the potential process capability on the other. In particular, we will get to know the central capability indicators CP, CPK, PP, or PPK, but also work on the so-called Taguchi Capability Index CPM, which belongs to the so-called second-generation capability indicators. We will use simple calculation examples to calculate the most important key figures step by step including manually, in order to understand how the capability figures shown in the output window are created in the first place. We will also understand what the z-benchmark performance indicator means, and how it relates to the sigma level. Using other performance indicators such as observed performance or expected performance, we will then also be able to assess process capability both, within and between subgroups. We will get to know the very useful Capability Six Pack function, which will help us very quickly, especially in turbulent day-to-day business to calculate all the necessary analyses, which are also required in advance of the actual process capability analysis in just a few steps. Based on the knowledge we have learned and the analysis results available, we will then be able to assess the process capability of our die casting process in a differentiated manner, and thus derive appropriate measures to improve process capability. Once the improvement measures have been implemented, we will finally carry out a new process capability analysis, and use the capability indicators to compare the improved process with the original unimproved process in detail.


  • Fundamentals of standard regulations regarding process capability
  • Basic principle and logic of the process capability definition
  • Process yields versus process capability
  • Process capability indices: PP, PPL, PPU, PPk
  • Process capability for centered processes
  • Process capability for non-centered processes


MAIN TOPICS MINITAB TUTORIAL Minitab Training 27, Part 2

  • Preparatory work for the process capability analysis
  • Descriptive statistics as part of a process capability analysis
  • Test for normal distribution, Anderson-Darling test
  • Derivation of the probability plot from the probability function
  • Process stability analysis: Xbar and R-chart
  • Estimation methods for determining the standard deviation
  • Key figures for overall process capability
  • Key figures for potential process capability
  • Total standard deviation vs. standard deviation within the subgroups
  • Sigma level vs. process capability level
  • Observed performance, expected performance overall, expected performance within
  • Manual determination of the standard deviation for the potential process capability


MAIN TOPICS MINITAB TUTORIAL Minitab Training 27, Part 3

  • Manual derivation of key performance indicators
  • Manual derivation of the standard deviation with the R-bar method
  • Manual derivation of the „summarized standard deviation“
  • Benchmark-Z (Sigma level)
  • Working with the dot plot as part of a process capability analysis
  • Extraction of data information as part of a process capability analysis
  • Working with the „Capability Six Pack“ option