MAYURBHANJ SCHOOOL OF ENGINEERING�(MSE)

SUBJECT: IE&M

SATYA SWARUP DAS

LECTURER MECHANICAL ENGINEERING,

SUMMER-2022, 4^TH SEMESTER

DEVELOPMENT OF �SIX SIGMA

• Motorola launched the Six Sigma program in the 1980s
• General Electric initiated the implementation of Six Sigma in the mid-1990s
• Organizations in all industries have applied Six Sigma in recent years
• Six Sigma has replaced TQM and BPR as the key strategy for quality improvement

DEFINITIONS

• σ – Standard Deviation, a measure of variability
• Six Sigma – A quality improvement philosophy that focuses on eliminating defects through reduction of variation in a process
• Defect – A measurable outcome that is not within acceptable (specification) limits

TQM VERSUS SIX SIGMA

KEY SUCCESS FACTORS FOR�SIX SIGMA

• Committed leadership from top management
• Integration with existing initiatives, business strategy, and performance measurement
• Process thinking
• Disciplined customer and market intelligence gathering
• A bottom-line orientation and continuous reinforcement and rewards
• Training

SIX-SIGMA METRICS – �MEASURING DEFECT RATE

• Defects per unit (DPU) = number of defects discovered ÷ number of units produced
• Defects per million opportunities (DPMO) = number of defects discovered ÷ opportunities for error × 1,000,000

ESTIMATING DEFECT RATE – PROCESS CAPABILITY INDEX (CP)

• USL/LSL : Upper & Lower Specification Limit
• Cp = (USL –LSL) / (6σ)
• Example : Time to process a student loan application (Standard = 26 working days)
• Specification Limits : 20 to 32 working days
• σ : 2 working days
• Cp = (32 – 20)/ (6*2) = 1.00 (Three Sigma)

CP INDEX AND DPMO

ESTIMATING PROCESS CAPABILITY INDEX FROM A SAMPLE - CPK INDEX

• XBAR : average outcome from a sample
• S : standard deviation from a sample
• Cpk = min { (USL-XBAR) / (3S),

(XBAR-LSL) / (3S) }

• Example : XBAR = 25 days, S = 3 days
• Cpk = min { (32-25)/(3*3), (25-20)/(3*3)}

= min {0.77, 0.55} = 0.55

Six-Sigma Quality (Cp =2 with Mean Shifting from the Center)

Ensuring that process variation is half the design tolerance (Cp = 2.0) while allowing the mean to shift as much as 1.5 standard deviations.

K-SIGMA QUALITY LEVELS

• Six sigma results in at most 3.4 defects per million opportunities

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GE’S SIX-SIGMA �PROBLEM SOLVING APPROACH

1. Define
2. Measure
3. Analyze
4. Improve
5. Control

DMAIC - DEFINE

• Identify customers and their priorities
• Identify business objectives
• Select a six sigma project team
• Define the Critical-to-Quality (CTQ’s) characteristics that the customers consider to have the most impact on quality

DMAIC - MEASURE

• Determine how to measure the processes
• Identify key internal processes that influence CTQ’s
• Measure the defect rates currently generated relative to those processes

DMAIC - ANALYZE

• Determine the most likely causes of defects.
• Identify key factors that are most likely to create process variation.

DMAIC - IMPROVE

• Identify means to remove causes of the defects.
• Confirm the key variables and quantify the effects on CTQ’s
• Identify maximum acceptable ranges for the key variables and a system to measure deviations of the variable
• Modify the process to stay within the acceptable ranges

DMAIC - CONTROL

• Determine how to maintain the improvement
• Put tools in place to ensure that the key variables remain within the maximum acceptable ranges under the modified process

TOOLS FOR SIX-SIGMA �AND QUALITY IMPROVEMENT

• Elementary and advanced statistics
• Product design and reliability analysis
• Measurement
• Process control & Process improvement
• Implementation and teamwork
• Customer survey and feedback
• Lean thinking

ORGANIZATION FOR SIX SIGMA

• Project Champions – project selection and management, knowledge sharing
• Master Black Belts – instructors, coaches, technical leaders
• Black Belts – project team leaders and team members
• Green Belts – project team members, temporary team members

THANK YOU