Improving Processes With Six Sigma Tools

Importance of using Six Sigma Tools:

Six Sigma tools play a significant role in the implementation of Six Sigma in any organization. They are used in both DMAIC and DMADV approaches. They aid in quantifying the quality performance and aligning the company goals to achieve six sigma through constant improvements. They help to measure how the processes in manufacturing cycle are performing and which steps are inconsistent or inefficient. By knowing these stats, companies are better placed for process improvements and minimize defects to improve the quality of end products.

Types of Six Sigma tools:

There are many six sigma tools available that can be used for both six sigma and total quality management (TQM). Six Sigma inherits most of the tools from other quality management and statistical techniques in general, so adopting them isn’t a big deal for any organization that is aware of quality management principles. Following are major six sigma tools:

i.  Histograms:

Histogram is an old statistical tool used to estimate the probability distribution of a continuous variable. It is a graphical representation of frequency of occurrences of defects/issues for multiple processes or a single process over the time. It is somewhat similar to bar chart.

By drawing histogram, we are able to determine the probability curve to determine how a particular process is performing at various intervals or with specific inputs provided. Among other six sigma tools, Histogram provides an easy way to measure the performance of any process and helps analyze the effect of improvements or measures taken to ensure quality.

ii.  Pareto Chart:

It won’t be wrong if we say that Pareto Chart is a combination of both line and bar charts. It is a type of histogram to determine the frequency of issues/defects occurring in defined processes. In quality management Juran practiced the 80/20 principle of Vilfredo Pareto, which means that 80 percent of problems lie in 20 percent of causes. It means that if we emphasize on 20 percent of problematic processes, we are able to resolve 80% of our issues.

Pareto Chart helps us identify those 20 percent of problematic processes. We plot error frequency tally against the processes and the largest tally determines that which process is causing more defects. A Pareto chart can easily be created in Microsoft excel. It is considered one of the important six sigma tools for efficient continuous improvements.

iii.  Ishikawa diagram:

It is also called fishbone diagram or cause-and-effect diagram. In quality management, it is important to determine root cause of problems and take preventive measures accordingly. So, if we do preventive actions instead of corrective actions, our processes will eventually be creating fewer defects and hence six sigma objectives can become a reality. Along with Pareto chart, ishikawa diagram comes under the process of root cause analysis to determine the root causes of defects.

iv.  Control Chart:

As we know that defect is an outcome that is not desired by the customer. And in six sigma, we are basically controlling defects. Control Chart is an important six sigma tool that measures the performance of the processes to determine defects. In this chart, we define control limits or acceptable quality limits set out based on customer expectations and depict them with horizontal lines on Y and -Y axis. After that, we plot the outcomes of our processes or products on Y axis and count the number of occurrences that fall outside the control or acceptable limits. In this way we determine that how many defects are occurred.

v.  Others:

There are many other six sigma tools that are used by different organizations to maintain quality. They include:

• Pick chart
• Failure mode and effects analysis (FMEA)
• CTQ tree
• Chi-square test etc.