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A ‘helicopter view’ of Six Sigma

I have been asked about this several times in the last couple of weeks, so here is my very high-level view of Six Sigma:

Six Sigma is a business management strategy, developed by Motorola in the mid 1980s, that aims to improve quality by identifying and removing the causes of errors and variability in manufacturing and business processes.

The term ‘Six Sigma’ comes from statistics; if you look at a normal distribution of parameters, then at six standard deviations (sigma) between the process mean and the specification limit there will be only 3.4 items per million that are defective. Applying the six sigma acceptance standard to any process gives a particularly low defect rate so it is seen as a quality ideal, a very high quality standard that can be challenging to attain.

Although this is still a valid definition within statistical process control and manufacturing processes, ‘Six Sigma’ is now also used for a broader range of business quality improvement activities. It uses a range of quality management methods, including statistical techniques, and is implemented by specially trained expert practitioners. Six Sigma projects undertaken within an organisation all follow a defined sequence of activities and have specific, objective, financial targets.

As with other quality management approaches, Six Sigma requires the reduction of process variations, the measurement and improvement of processes, and the commitment of all staff in the organisation, especially management, to improve quality. In some regards it is simply an evolution of Total Quality Management, although it differs in that it has:

  • A focus on achieving quantifiable financial returns for each ‘project’
  • Increased emphasis on strong management leadership
  • Increased emphasis on using objective data and statistical analysis as a basis for decision-making
  • Implementation via trained experts: ‘Black Belts, ‘Green Belts’, etc; quite an industry has built up around the development and deployment of these experts and their working methods.

Six Sigma quality management uses formal, well-documented methodologies that are derived from Deming’s famous Plan-Do-Check-Act cycle and applied by the Black Belt or Green Belt (or any other colour…) trained practitioners.

DMAIC for improving an existing business process:

  • Define the improvement project with a defined team and clear goals
  • Measure key parameters and performance of the current process and collect relevant data
  • Analyse the data to identify the real root cause of current performance issues and to identify cause-and-effect relationships
  • Improve the process based upon data analysis and prove the required improvements have really been achieved
  • Control the new process to make sure that any deviations from the planned results are corrected before defects or errors are produced. Implement in production and continuously monitor the process to ensure it continues meeting requirements.

DMADV (or DFSS – ‘Design For Six Sigma’) for creating new processes:

  • Define design goals for the new process that match customer requirements and company strategy, and form a defined team
  • Measure and identify the key parameters or characteristics that are essential for meeting customer requirements
  • Analyse these parameters or characteristics and create high-level designs that will produce or meet them; evaluate and select the best design
  • Design the process in detail
  • Verify the design, make sure it performs as required, implement it in production and continuously monitor the process to ensure it continues meeting requirements.

In some regards, Six Sigma (and, for that matter, TQM) could be seen as merely the ‘formalisation of common sense’ in quality management. However, that would underestimate the benefit of applying a well planned, structured, consistent methodology – along with some analytical rigour – across a company to secure business improvement.

As far as quality management techniques go, Six Sigma is still the ‘new kid on the block’ and, although some observers criticise it as being too wrapped up in jargon and whizzy processes for its own good, the methodology has been thoroughly developed and proven in a wide range of organisations. Applying it well, consistently, and for the long-term can make a real difference to many businesses.

So what is Six Sigma in a nutshell? Think of it as a ‘Continuous Improvement technique for businesses and products that uses really well trained practitioners, a rigorous analytical methodology and very high quality standards’ and you won’t be far wrong.

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