Define Flashcards
Lean Vs Six Sigma
Lean: - Simplify processes (fast and efficient)
• Eliminate waste
• Reduce cost
• Increase speed
Six Sigma: (effective and improve quality)
• Eliminate errors
• Reduce variation
• Make system changes
• Sustain improvements
Process Variation Equation
Variation is due to differences in
• Manpower (people)
• Machines (e.g., computers, plants)
• Materials (soft and hard)
• Methods (e.g., procedures, training)
• Measurement (e.g., standards, policies, equipment)
• Mother nature (environment)
How to Measure the Variation?
Range: min-max
Std dev - σ (measure the data variation about the mean)
Variance - σ2
What is the limitation to variances and std devs?
Variances can be added together, but standard deviations cannot be added.
σT2 = σ12 + σ22 + σ32 (It is correct)
σT = σ1 + σ2 + σ3 (It is not correct.)
Define empirical rule
tells you what percentage of your data falls within a certain number of standard deviations from the mean.
• Based on one-year cost-per-call data for a service organization
o Mean (μ) cost per call = $16.00
o Standard deviation, σ = $2.00
• 99.73% of cost-per-call variation is between $10 and $22.
• The costs of 99.73% of calls vary from $10 to $22.
Define Z-score
The number of standard deviations between The process mean and a data point in the process
Zlt = Zst - 1.5
How go calculate z-score process capability
• A service organization has decided to limit the cost per call from $7.00 to $25.00.
• What is the help desk performance for cost per call in terms of the Z-score? • Whereas:
o Mean (μ) cost per call = $16.00 o Standard deviation, σ = $2.00
o USL (upper spec. limit) = $25.00 o LSL (lower spec. limit) = $7.00
On the right from the mean, Z-score = (25 – 16)/2 = 4.5
On the left from the mean, Z-score = (7 – 16)/2 = -4.5
Average industrial sigma level
World-class industrial sigma level
Average industrial sigma level = 4
World-class industrial sigma level = 6 and above
Defect
Failing to deliver what customer wants or not meeting Critical to Customer (CTC) requirement(s).
Opportunity
Number of possibilities (CTC requirement) for a defect.
Defective unit:
Non-conformance unit or unit with one or more defects. If a defect is minor and accepted by customer, unit is not
considered defective
DPMO
how many number of requirements are not met with respect to million requirements
DPU, DPO, DPMO
DPU: number of defects per unit observed during a process
DPO: DPU divided by the number of opportunities
DPMO: DPO multiplied by one million.
DPMO
# of Units: # of Invoices = 2,000 in a week
# of Defective invoices: rejected invoices = 10
Opportunities (name, quantity, price etc., per invoice) = 5 # of defects in 10 defective invoices = 13
of Units: # of Invoices = 100,000 in a year
# of Defective invoices: rejected invoices = 8,000
Opportunities (name, quantity, price etc., per invoice) = 5 # of defects in 8,000 defective invoices = 33,000
Bob Galvin
Motorola CEO struggling to compete with foreign manufacturers, due to poor quality in products
Bill Smith
coined the expression “Six Sigma” to indicate improvement measures and credited as the father of Six Sigma
Dr. Mikel J. Harry
formulated the MAIC (Measure-Analyze-Improve-Control) approach to achieve Six Sigma level of quality
General Electric (GE) added Define phase to MAIC
Walter A. Shewhart
Developed control charts to detect special causes
Known as father of statistical process control
W. Edward Deming
Emphasized the 14 obligations of top management for improvement
Developed PDCA/PDSA cycle—PDCA a.k.a. Deming/Shewhart cycle
Joseph M. Juran
Developed managerial processes—quality trilogy (planning, control, & improvement)
Helped businesses understand continuous process improvement
Philip B. Crosby
• Originated the zero defects concept
• Established 14 steps to quality improvement
Armand V. Feigenbaum
• Originated concept of total quality control (TQC)
• Served as ASQ president for two consecutive terms
Kaoru Ishikawa
Developed the cause and effect diagram and CWQC (Company-wide QC)
Part of JUSE (Japanese Union of Scientists and Engineers),
Genichi Taguchi
• Developed the law for financial loss to society due to bad quality
• Developed robustness concept for quality
Shigeo Shingo
• Developed the concept of poka-yoke (mistake-proofing)
• Developed the concept of the single-minute exchange of die (SMED)
What is six sigma
Strategy to resolve business problems. Provides methodology and provide tools.
Program centered around customer service.
Allows a better understanding of process by data and statistics to fix business problems.
DMAIC vs DMADV
DMAIC: improve current process capabilities.
DAMDV: create new or redesign process based on customer requirements
- DFSS: design for six sigma
- IDOV: identify, define, optimize, validate
What is the DMAIC phases
Six Sigma DMAIC Approach
