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What is Six Sigma?

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What is Six Sigma?

• set of tools for significant improvements without huge investments,
• strategic initiative,
• systematic approach to reduce the occurrence of mistakes,
• disciplined methodology,
• company culture,
• decision-making based on facts,
• part of the company genetic code.

Six Sigma offers to companies the way to make fewer mistakes in all their activities (ranging from filling in an order to the most complicated manufacturing process or service delivery) by eliminating errors before they appear.

Basic Six Sigma concepts:

• Six Sigma – term coined by the company Motorola,
• Sigma (σ) – standard deviation as a measure of process variability,
• Sigma quality level – process capability to fulfil required specifications,
• Six Sigma quality level – 3.4 DPMO in relation to a CTQ characteristic,
• Critical to Quality Characteristic (CTQ) – quality attribute important for a customer.

DMAIC improvement methodology

5 phases indicated by DMAIC symbols

D-DEFINE

• project selection;
• problem definition, definition of aims and project scope;
• gaining facts about a process and customers;
• team selection, setting deadlines.

The aim of the Define phase is to identify „what, who, why, with whom, how much and by when“ will have been improved. It is to define goals clearly but not „how“ they will be achieved. „How“ is the aim of DMAIC Lean and Six Sigma project.

M-MEASURE

• determination of possible input factors (causes) which can influence a defective output (consequence);
• verification of a measurement system and its possible correction;
• analysis of the frequency with which defects occur;
• data collection on the defect occurence (monitoring an output) and recording input factors (inputs);
• process behaviour description in time, process stability evaluation;
• understanding the capability determining the occurrence of defects.

The aim of the Measure phase is to collect and evaluate information on the current situation (monitoring the defect occurrence, measuring process outputs and recording inputs).

A-ANALYZE

• analyzing data about the current situation according to single possible causes and determining the critical ones (input analysis);
• with the help of specific statistical methods and tools, identifying key process parameters important for explaining a number of non-conform products (determining the relation Y=f(x)).

The aim of the Analyze phase is to determine key causes of a problem, i.e. critical input factors that have a significant impact on the occurrence of mistakes.

I-IMPROVE

• creation of solutions removing main causes of mistakes;
• evaluating benefits, costs and risks of solutions;
• modelling and optimising the set-up.

The aim of the Improve phase is to create, test and implement solutions removing main causes of mistakes.

C-CONTROL

• process standardization to guarantee improvement viability;
• continuous monitoring key process characteristics that produce a product or service guarantees that the same problem will not occur again.

The aim of the Control phase is to quarantee continuous maintenance of an improvement.

During Six Sigma implementation a key role is performed by employees in these positions:

Champion

He presents the vision of a successful Six Sigma deployment. He determines projects for Black Belt training graduates and sets their priorities. He leads them strategically, gives them pieces of advice and supports their activities. He removes internal barriers that might prevent a successful project completion.

Sponsor

Process owner (responsible for a process) who participates in project selection. He is responsible for authorising process changes. He approves dates for employee trainings. He monitors team progress and supports it. He contributes to sustaining results of an improvement project.

Master Black Belt

He understands company strategy and has general knowledge of company activities. As a partner of a Champion, he creates and carries out trainings for different company levels. Ha has deep knowledge of Six Sigma methodology. He helps to identify projects. He coaches Black Belts in project work and helps with their training and certification. He cooperates in preparing project reports. He is acquainted with best practises and provides them to the whole company.

Black Belt

He is an expert in Six Sigma strategy, is enthusiastic about it and motivates others with his positive approach. He supports ideas of Champions and in urgent cases he asks for help. He identifies obstacles in projects, leads project teams and informs management about progress. He influences without a formal authority and has an impact on the application of the most effective tools. He receives input information from operators, supervisors and team leaders. He teaches and trains Six Sigma strategy methods and tools.

Green Belt

He devotes approximately 20 – 30% of his working time to solving Six Sigma projects. At the same time, he fulfils his ordinary duties. He cooperates in Black Belt projects within his existing duties. He learns Six Sigma methodology and applies it in his partial projects. He continues to study and implement Six Sigma methods and tools after the project completion.