Six Sigma means you can have 3.4 defects per 1000,000 opportunities.
2-Sigma 308,537 30.85
3-Sigma 67,000 6.7
4-Sigma 6,200 0.62
5-Sigma 233 0.02
6-Sigma 3.4 0.0034
99% defect free is 3.8 sigma. 99.99966% defects free is 6 sigma.
Defects means any product characteristic that deviates outside of specified limits.
Opportunity is anything you measure or test. By adopting Six sigma
You can implement Six Sigma in Five phases each phase has 3 steps.
Identify the scope of customer's problem. It is important to streamline the internal processes affecting CTQ.
1) Identify Project critical to quality (CTQ). These are the key processes required to meet customer needs.
Identify the key leaders ( Plant manager , Customer)
2) Develop team Charter. Create business case-Define the problem and goal statement and scope of the project. communicate this to all team member. Define team members role, responsibilities, and expectations. Team defines why the project is important, its benefits and consequences of not doing the project. prioritizes business. Define constraints, problems and goal statement with project requirement time..
3) High level process is created. 'COPIS' (Customer,Output,Process,Input,Supplier) story-board.
Drill down high-level process so that measurement can be taken to locate improvrmrnt souces.Convert process into numbers to measure and improvemnt support. Relate Customer meeds to a measurable internal process.
1) Select CTQ characteristic. High level CTQ is drill down (Fishbone).
Use QFD (Quality function deployment) - Framework for rating relationship between CTQ and internal processes. Narrow the focus by translating CTQ into small measurable processes. Customer expectations are 'What'(Rank 1 Low-5 Critical)- Internal processes are 'How'(Rank 1-Low,3-Medium,9-High) to solve it.In the second step 'how' become 'what' and have new set of how's.
Precess mapping is useful to graphically represent processes. Create shared view
Pareto chart - Need historical data, Narrow the focus, 80-20 principal, few factors impacting performance.
Fishbone diagram-known as cause and effect diagram, Its a structure to look at the effects finding causes.. FMEA-Failure Modes and effects analysis - Identifies ways a product/process can fail and plan to prevent failures. Documenting risk reduction action. This is advisable for high risk projects. Assign Severity, occurence and detection rating and calculate RPN (S * O * D). Take appropriate action to reduce RPN(Risk Priority number) . Recalculate RPN = S * O * D.
2) Define performance standard, Operation definition, Specification limits, Defect definition. It is important
to collect data. The data can be discrete (can not be divide yes/no, True/False, under/over) or Continuos ( refine to an infinite number $,amt,time,etc.)
Continuous data is
3) Establish measurement plan. Strategy for collecting data. It is important to have Precision, Accuracy and resolution while collecting the data. Repeatability ( same operator diff equipment) and Reproducibility ( same quipment but different oprator) is critical, this make sure we are collecting valid data. Collect the data on current process (Historical or Actual)
Evaluate and analyze.
1)Evaluate process capability,(Where are we now ?)
2) Performance objective is defined by team and create improvement goal (Where we are going ?)
3) Identify variation sources of current system (What can keep us from acheiving the goal ?)