Introducción al concepto de seis sigma

1. 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

2. Definitions
 s – 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

3. TQM Versus Six Sigma
TQM Six Sigma
A management
philosophy of quality
improvement
A philosophy that focuses
on defect reduction and
cost reduction
Encourages involvement
of all employees
Relies on a selected group
of highly-trained employees
Senior management
provides direct support
Senior management is held
accountable for results

4. 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

5. 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

6. Estimating Defect Rate –
Process Capability Index (Cp)
 USL/LSL : Upper & Lower Specification Limit
 Cp = (USL –LSL) / (6s)
 Example : Time to process a student loan
application (Standard = 26 working days)
 Specification Limits : 20 to 32 working days
 s : 2 working days
 Cp = (32 – 20)/ (6*2) = 1.00 (Three Sigma)

7. Cp Index and DPMO
Cp Index DPMO
1 2,700
1.33 63
1.5 6.8
2 0.002

8. 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

9. 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.

10. k-Sigma Quality Levels
 Six sigma results in at most 3.4 defects per
million opportunities

11. GE’s Six-Sigma
Problem Solving Approach
1. Define
2. Measure
3. Analyze
4. Improve
5. Control

12. 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

13. 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

14. DMAIC - Analyze
 Determine the most likely causes of
defects.
•Identify key factors that are most
likely to create process variation.

15. 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

16. 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

17. 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

18. 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