79  Quality Management and Six Sigma

79.1 Concept

Quality = fitness for use — Joseph Juran; conformance to requirements — Philip Crosby; meeting and exceeding customer expectations — Armand Feigenbaum. W. Edwards Deming turned Japan into a quality powerhouse with Plan-Do-Study-Act (PDSA). The 1980s TQM movement and 1986 launch of Six Sigma at Motorola transformed global manufacturing and services.

79.2 Quality Gurus

TipQuality gurus
Guru Contribution
Walter Shewhart (1924) Statistical Process Control (SPC); PDCA cycle
W. Edwards Deming 14 Points; PDSA; Japan quality revival
Joseph Juran Quality Trilogy (Planning, Control, Improvement); 80/20
Philip Crosby “Zero Defects”; Quality is Free; 14 steps
Armand Feigenbaum TQC (Total Quality Control)
Kaoru Ishikawa Fishbone diagram; Quality Circles
Genichi Taguchi Robust design; Quality Loss Function
Shigeo Shingo Poka-Yoke (mistake-proofing); SMED
Masaaki Imai Kaizen

79.3 Deming’s 14 Points (Key Highlights)

TipDeming’s 14 points (selected)
  • Create constancy of purpose.
  • Adopt the new philosophy.
  • Cease dependence on inspection.
  • End award by price tag alone.
  • Improve constantly.
  • Institute training.
  • Institute leadership.
  • Drive out fear.
  • Break down barriers between departments.
  • Eliminate slogans/exhortations.
  • Eliminate numerical quotas.
  • Remove barriers that rob workers of pride.
  • Institute education and self-improvement.
  • Top management commitment.

79.4 PDCA / PDSA Cycle

Plan → Do → Check (Study) → Act — Shewhart 1924; Deming refined.

79.5 Quality Costs (PAF Model)

TipCosts of quality
  • Prevention costs — training, planning.
  • Appraisal costs — inspection, testing.
  • Internal Failure costs — rework, scrap.
  • External Failure costs — warranty, returns, lost customers.

79.6 Quality Tools — Ishikawa’s 7 Basic Tools

TipIshikawa’s 7 QC tools
  1. Check sheet.
  2. Histogram.
  3. Pareto chart (80/20).
  4. Fishbone / Ishikawa / Cause-Effect diagram.
  5. Scatter diagram.
  6. Control chart (Shewhart).
  7. Stratification / Flow chart.

79.7 7 New Management & Planning Tools

Tip7 new tools
  • Affinity diagram · Tree diagram · Relations diagram · Matrix diagram · Matrix data analysis · Arrow diagram · Process Decision Program Chart (PDPC).

79.8 TQM (Total Quality Management)

TipTQM principles
  • Customer focus.
  • Total employee involvement.
  • Process-centred.
  • Integrated system.
  • Strategic and systematic approach.
  • Continual improvement (Kaizen).
  • Fact-based decision making.
  • Communications.

79.9 Six Sigma

Six Sigma = a disciplined, data-driven methodology to reduce process variation and defects to <3.4 per million opportunities (DPMO). Originated at Motorola (Bill Smith 1986), popularised by Jack Welch at GE (1995).

TipSix Sigma — sigma vs DPMO
Sigma DPMO Yield
1σ 691,462 30.85 %
2σ 308,538 69.15 %
3σ 66,807 93.32 %
4σ 6,210 99.379 %
5σ 233 99.977 %
6σ 3.4 99.9997 %

79.10 DMAIC and DMADV

TipSix Sigma methodologies
  • DMAIC — for improvement of existing processes.
    • Define · Measure · Analyse · Improve · Control.
  • DMADV (DFSS — Design For Six Sigma) — for new processes.
    • Define · Measure · Analyse · Design · Verify.

79.11 Six Sigma Belts

TipSix Sigma belt hierarchy
  • Champion / Sponsor — leadership.
  • Master Black Belt — full-time SS coach.
  • Black Belt — leads projects.
  • Green Belt — part-time project member.
  • Yellow Belt / White Belt — awareness.

79.12 Lean Six Sigma

Combines Lean (waste elimination — 7 wastes: TIMWOOD) with Six Sigma (variation reduction): - Transportation · Inventory · Motion · Waiting · Over-production · Over-processing · Defects (TIMWOOD); add S for Skills (TIMWOODS).

79.13 Statistical Process Control (SPC)

TipControl charts
  • X̄ chart — mean.
  • R chart — range.
  • σ chart — standard deviation.
  • p chart — proportion defective.
  • np chart — number defective.
  • c chart — defects per unit.
  • u chart — defects per unit varying lot.
  • CUSUM, EWMA — modern.

Control limits: UCL = X̄ + 3σ; LCL = X̄ − 3σ.

79.14 Process Capability

TipProcess capability
  • Cp = (USL − LSL) / 6σ — potential.
  • Cpk = min((USL − μ)/3σ, (μ − LSL)/3σ) — actual capability.
  • Cp / Cpk ≥ 1.33 acceptable; ≥ 2.0 for Six Sigma.

79.15 Quality Standards

TipQuality standards
  • ISO 9001 — Quality Management Systems.
  • ISO 14001 — Environment.
  • ISO 45001 — OH&S.
  • ISO 27001 — Information Security.
  • ISO/TS 16949 / IATF 16949 — Automotive.
  • HACCP — Food.
  • GMP — Pharma.
  • CMMI — IT/software (5 levels).
  • Malcolm Baldrige Award (US).
  • Deming Prize (Japan).
  • EFQM Excellence Model (Europe).
  • CII-Exim Bank Award (India).
  • IMC Ramkrishna Bajaj National Quality Award.

79.16 Indian Quality Movement

TipIndian quality movement
  • JRD Tata — early quality champion.
  • Tata Steel — Deming Prize 2008.
  • Sundaram-Clayton — Deming Prize 1998.
  • CII-TQM Division.
  • QCI — Quality Council of India.
  • BIS — Bureau of Indian Standards.
  • NABL — accreditation lab.
  • NABH — hospitals accreditation.
  • FSSAI — food safety.

79.18 Practice Questions

Q 01Six SigmaEasy

Six Sigma was developed at:

  • AMotorola (1986)
  • BToyota
  • CGE
  • DIBM
View solution
Correct Option: A
Motorola, Bill Smith, 1986.
Q 02DPMOMedium

Six Sigma DPMO is:

  • A3.4
  • B34
  • C340
  • D3,400
View solution
Correct Option: A
3.4 defects per million opportunities.
Q 03DMAICMedium

DMAIC stands for:

  • ADefine-Measure-Analyse-Improve-Control
  • BDefine-Manufacture-Analyse-Implement-Check
  • CDiscover-Measure-Adjust-Improve-Control
  • DDocument-Measure-Apply-Inform-Conclude
View solution
Correct Option: A
Improvement methodology.
Q 04FishboneMedium

Fishbone diagram is by:

  • AKaoru Ishikawa
  • BDeming
  • CJuran
  • DCrosby
View solution
Correct Option: A
Kaoru Ishikawa; aka cause-effect diagram.
Q 05CrosbyMedium

"Zero Defects" and "Quality is Free" are by:

  • APhilip Crosby
  • BDeming
  • CJuran
  • DTaguchi
View solution
Correct Option: A
Crosby.
Q 06JuranHard

Juran's Quality Trilogy is:

  • APlanning · Control · Improvement
  • BPDCA
  • CDMAIC
  • D5S
View solution
Correct Option: A
Juran Trilogy.
Q 07Poka-YokeHard

Poka-Yoke (mistake-proofing) is by:

  • AShigeo Shingo
  • BOhno
  • CIshikawa
  • DTaguchi
View solution
Correct Option: A
Shigeo Shingo.
Q 08TaguchiHard

Quality Loss Function is by:

  • AGenichi Taguchi
  • BDeming
  • CCrosby
  • DJuran
View solution
Correct Option: A
Taguchi.
Q 09PDCAMedium

PDCA cycle was created by:

  • AWalter Shewhart
  • BDeming
  • CJuran
  • DIshikawa
View solution
Correct Option: A
Shewhart originated; Deming popularised.
Q 107 wastesMedium

"TIMWOOD" represents:

  • ALean's 7 wastes
  • BSix Sigma steps
  • CQuality gurus
  • DISO standards
View solution
Correct Option: A
Transport · Inventory · Motion · Waiting · Overproduction · Overprocessing · Defects.
Q 11ISO 9001Easy

ISO 9001 is for:

  • AQuality Management Systems
  • BEnvironment
  • CInformation security
  • DFood safety
View solution
Correct Option: A
QMS standard.
Q 12WelchHard

Six Sigma was popularised at GE by:

  • AJack Welch
  • BJeff Immelt
  • CBill Smith
  • DTim Cook
View solution
Correct Option: A
Jack Welch 1995.
Q 13CpkHard

Cpk measures:

  • AActual process capability
  • BCustomer satisfaction
  • CCycle time
  • DDPMO
View solution
Correct Option: A
Captures mean position relative to specs.
Q 14Deming PrizeMedium

Deming Prize is given in:

  • AJapan
  • BUSA
  • CEurope
  • DIndia
View solution
Correct Option: A
JUSE Japan since 1951.
Q 15Match gurusHard

Match:

(i) Fishbone (a) Crosby
(ii) Zero Defects (b) Taguchi
(iii) Quality Loss Function (c) Ishikawa
(iv) Poka-Yoke (d) Shingo
  • A(i)-(c), (ii)-(a), (iii)-(b), (iv)-(d)
  • B(i)-(a), (ii)-(b), (iii)-(c), (iv)-(d)
  • C(i)-(b), (ii)-(c), (iii)-(d), (iv)-(a)
  • D(i)-(d), (ii)-(a), (iii)-(c), (iv)-(b)
View solution
Correct Option: A
Fishbone — Ishikawa; ZD — Crosby; QLF — Taguchi; Poka-Yoke — Shingo.

79.18.1 Advanced Format Questions

AR 1Assertion-ReasonHard

A: Six Sigma allows only 3.4 DPMO.
R: Higher sigma level implies lower defect rate.

  • ABoth true; R explains A
  • BBoth true; R does not explain A
  • CA true, R false
  • DA false, R true
View solution
Correct Option: A
S 1Statement-basedMedium

7 QC tools (Ishikawa): (i) Check sheet. (ii) Histogram. (iii) Pareto. (iv) Fishbone.

  • AAll four (+ Scatter, Control, Stratification)
  • B(i) and (ii) only
  • C(iii) and (iv) only
  • D(iv) only
View solution
Correct Option: A
N 1NumericalMedium

USL = 110; LSL = 90; σ = 2. Cp =

  • A1.67
  • B1.00
  • C2.00
  • D3.33
View solution
Correct Option: A
Cp = (USL−LSL)/6σ = 20/12 ≈ 1.67.
N 2NumericalHard

X̄ = 100; σ = 2. UCL (3σ) =

  • A106
  • B103
  • C102
  • D100
View solution
Correct Option: A
100 + 3×2 = 106.

79.19 Quick Recall

ImportantQuick recall
  • Gurus: Shewhart (SPC, PDCA) · Deming (14 points, PDSA) · Juran (Trilogy, 80/20) · Crosby (Zero Defects) · Feigenbaum (TQC) · Ishikawa (Fishbone, QC circles, 7 tools) · Taguchi (Robust design, QLF) · Shingo (Poka-Yoke, SMED) · Imai (Kaizen).
  • PDCA/PDSA: Plan-Do-Check/Study-Act.
  • PAF costs: Prevention · Appraisal · Internal failure · External failure.
  • 7 QC tools: Check sheet · Histogram · Pareto · Fishbone · Scatter · Control chart · Stratification.
  • 7 new tools (planning): Affinity, Tree, Relations, Matrix, Matrix data, Arrow, PDPC.
  • TQM: customer focus · employee involvement · process · continual improvement · facts.
  • Six Sigma — Motorola (Bill Smith 1986); GE Welch 1995. 3.4 DPMO, 99.9997 % yield.
  • DMAIC (improve) · DMADV / DFSS (new design).
  • Belts: Champion · MBB · BB · GB · YB/WB.
  • Lean — 7 wastes (TIMWOOD) + Skills.
  • SPC: X̄, R, σ, p, np, c, u, CUSUM, EWMA; UCL/LCL = mean ± 3σ.
  • Process capability: Cp = (USL−LSL)/6σ; Cpk uses mean position; ≥ 1.33 acceptable; ≥ 2 Six Sigma.
  • Standards: ISO 9001 (QMS) · 14001 · 45001 · 27001 · IATF 16949 · HACCP · GMP · CMMI · Baldrige · Deming Prize · EFQM · CII-Exim · IMC-RBNQA.
  • India: Tata Steel · Sundaram-Clayton · QCI · BIS · NABL · NABH · FSSAI.
  • Modern: Lean SS 4.0 · AI/ML quality · IoT · Digital Twin · Quality 4.0 · big-data SPC · blockchain traceability · VoC analytics · NPS · RPA.