Integral Logistics Management — Operations Management and Supply Chain Management Within and Across Companies

18.2.4 Quality Control: PDCA Control Phase, Part 1 — DMAIC Measure Phase and Analyze Phase, Part 1

Intended learning outcomes: Produce an overview on tools used in quality control in their original usage stemming from production engineering. Identify deliverables of the Measure phase as well as the Analyze phase.

Quality control encompasses the operational techniques and the activities used to fulfill and verify requirements of quality [ISO8402]. It is also defined as a set of activities or techniques such as measurement and inspection of one or more characteristics of a unit and comparison of the results with set requirements to ensure that conformance with quality requirements is being met.

Quality control is the attempt to implement the predefined targets from quality planning in reality; that is, it measures for conformance to quality requirements. The techniques of quality control can be used for both monitoring a process and correcting or eliminating defects or failures.

In the PDCA-cycle, the Control phase comprises the necessary tasks of quality control. In order to control the success of the Do phase, the respective tools have to be implemented before the Do phase and used for rechecking afterwards. In the Six Sigma method, quality control comprises two of the DMAIC phases, namely, Measure, and Analyze. Again, in order to control the success of the Improve phase, the respective tools have to be implemented before the Improve phase and used for rechecking afterwards.

In the Measure phase, the task is to determine how the spoken needs of the customers, the CTQs, will be specified in measurable terms using tools. The appropriate measurement system is then installed or an existing system improved. Here see Section 18.1.4. Further, actual current performance is quantified and the target goal determined (for example, increase process stability from three sigma to four sigma).

Some quality control tools and tests for this task are, for example, ABC classification or Pareto chart, sampling plans, and statistical process control to determine process capability and process performance.

The deliverables of the Measure phase can be reviewed and revisited as follows:

  • Is there agreement on the critical characteristics, and is there a detailed description of their measurability?
  • Has a plan been drawn up showing what data will be captured and what measurement system will be used? Have the data been gathered?
  • Has the current variation of the process (current sigma level) been calculated and opportunities for improvement defined?

In the Analyze phase, the task is to identify root causes of variation and defects. Now it is important to provide statistical evidence of current deviations and to then formulate options for improvement (improvement goals). Thus, the Measure and Analyze phases both encompass activities of quality control.

Quality control in its original usage stems from production engineering. The tools used include risk analysis, such as failure mode and effects analysis (FMEA), design of experiment (DOE), and hypothesis testing, such as analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA).

Further tools for this step are cause and effect diagram (fishbone, or Ishi­kawa diagram), histograms, quality control charts, correlation diagrams, checklists, and general graphical representations, such as time series diagrams, pie charts, bar charts, Gantt charts, or network diagrams.

The deliverables of the Analyze phase can be reviewed and revisited as follows:

  • Were data and process analysis conducted and the gaps between actual and target process performance determined?
  • Have the root causes of variation and defects been found and prioritized according to importance?
  • Were the performance deficits communicated and converted to financial quantities? (Here see the discussion in Section 1.3.1 on opportunity costs.)

Course section 18.2: Subsections and their intended learning outcomes

  • 18.2 Quality Management Tasks at the Operations Level

    Intended learning outcomes: Produce an overview on the Deming Cycle (PDCA Cycle) and the Shewhart Cycle as well as the Six Sigma Phases. Present the phases of quality planning, control, assurance, and activation of the Deming Cycle. Describe the Six-Sigma phases of define, measure, analyze, improve, and control. Differentiate between continual improvement and reengineering.

  • 18.2.1 The Deming Cycle (PDCA Cycle) and the Shewhart Cycle

    Intended learning outcomes: Produce an overview on The Shewhart cycle developed in statistical quality control. Present the Deming cycle. Describe quality management tasks in the Deming cycle.

  • 18.2.2 DMAIC — The Six Sigma Phases

    Intended learning outcomes: Present DMAIC, the Six Sigma phases. Describe the tasks in the Six Sigma phases. Differentiate between DMAIC, RDMAIC, DMAICT, and DMADV.

  • 18.2.3 Quality Planning: PDCA Plan Phase — DMAIC Define Phase

    Intended learning outcomes: Identify the cause of differences between stakeholders’ expectations and actual product or process characteristics. Explain quality function deployment – the house of Quality and 10 steps of implementation. Describe the SIPOC diagram and the CTQ matrix.