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Six Sigma - Understanding basic concepts. Business Relevance of 6 σ. Substitution. Improvement (in Qly, Cost, Del & Serv.). Govt. Policies. Competition. Maintenance (Old Products & Services). Customer. Gap analysis – Do’s & Needs. Quality . Supplier. Defect Free. Needs. Customer.
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Business Relevance of 6σ Substitution Improvement (in Qly, Cost, Del & Serv.) Govt. Policies Competition Maintenance (Old Products & Services) Customer
Gap analysis – Do’s & Needs Quality Supplier Defect Free Needs Customer Delivery Do’s Cycle Time Price Cost Gaps to be addressed continuously
Six sigma – Simple concept 6 σ is a level of performance that reduces the defects in products & services significantly A set of statistical tools that helps to measure, analyse, improve and control processes. A commitment to customers to achieve an acceptable level of performance Mind Set + Tool Set = Six σ
6 Sigma Theme Customer focussed Processes are key drivers Fact driven and Proactive for creativity Result oriented - demands financial analysis to verify gains
6 Sigma Theme • Voice of Customer(VOC): Specs decided by customers (Dependent variable, say Y) - Response time; TAT; Breakdowns; Product performance, waiting time at ATM/counter etc. • Voice of Process (VOP): Variability of a process; Process variations cause defects (Independent variable, say x)
6 Sigma Quality Theme Six Sigma Quality Hitting the Target (Centralise the Process) Elimination of Process variability Process should be with minimum variability and on the target
What does 6 Sigma do? Statistical problem Statistical solution Real life problem Y y y = f(xi) Real life solution
Step 6 Control Step 5 Improve Step 4 Analyse Step 3 Measure Step 2 Define Step 1 Recognition 6 Sigma Steps - RDMAIC
Step 1 Recognition 6 Sigma Steps - RDMAIC • To identify the major business issues • To recognise key processes that need improvement • Areas that need break throughs • Identify critical to customer (CTC) • Drill down to CTQ (translating expectations to parameters); • Define specs, UL & LL, Targets Y= f (xi)
Step 1 Recognition 6 Sigma Steps - RDMAIC • Tools generally used • QFD Matrix • Importance gain matrix • Project selection criteria • high gain • low hanging fruits • Urgency • Efforts required
Step 2 Define Step 1 Recognition 6 Sigma Steps - RDMAIC • Define the key requirements to customer • Customers know their language • Listening to customers means understanding their needs. • Drill down the CTC • Define step will deliver • Project Chartering • (Goal, Milestone, Roles) • Process Mapping (SIPOC model) • Customer say… Engineers say.. • Long life 20,000 Hrs life • Reliable 3000 MTBF • Comfort cooling 24 ± 1 Deg C
Step 3 Measure Step 2 Define Step 1 Recognition 6 Sigma Steps - RDMAIC • Input, Process and output measures are to be defined • Measure process stability • Measure repeatability and reproducability • Measure current process capability Standard softwares are available to process the data
3 Sigma process 99.78% 95.44% 68.26% Upper Control Limit Total surface area 100% Lower Control Limit 1 1 1 1 1 1 X
Customer perceive and register the variance more than average
6 Sigma process (statistical vision) Upper Spec. Lower Spec. 6 6 X
Defects vs Defectives Defects Countable failures that are associated with a single unit. A single unit can be defective but may contain more than one defect. Defectives Completed units that are classified as bad or not meeting specs. Whole unit is said to be of defective.
Terminologies used DPU DPU= Defects / unit DPMO DPU x 1,000,000 DPMO = Opportunities per unit Defects = x 1,000,000 Opportunities = Defects per million opportunities
6 Sigma process (measures) Sigma Defects per Million (DPMO) 2 308,537 3 66,807 4 6,210 5 233 6 3.4 % non-defective 69.1% 93.32% 99.379% 99.9767% 99.99966% 24% 6% 0.6% 0.023%
Example 1 : 52 defects, 250 AMC proposals, 4 defects opportunities / proposal DPMO = [(52)/ (250*4)] X 1000000 = 52,000 = 3.1 Sigma level Traditional approach 5 applications were rejected (contains 52 defects) 5/250 = 2% rejection Example 2 : 99 defects, 750 products, 150 defects opportunities /product DPMO = [(99)/ (750*150) ]X 1000000 = 880 = 4.65 Sigma level Traditional approach 10 products were rejected (contains 99 defects) 10/750 = 1.33% rejection
Software (Minitab) outputs – some screens….. P > 0.05 Data follows normal distribution
Short term Long term Software (Minitab) outputs – some screens…..
Step 4 Analyse Step 3 Measure Step 2 Define Step 1 Recognition 6 Sigma Steps - RDMAIC • Identify cause & effect [ y = f (x) ] • Use analytical tools to vital few • Short list causes that are vital few which can be taken to improve phase
6 Sigma Steps - RDMAIC Identify and formulate causes Identify Opportunities Quantify and verify causes • process mapping • FMEA • QFD • Process Capability • Stratification • Seven QC tools • Why-why analysis • Brainstorming • Hypothesis tests • DOE • Identify success factor • List of opportunities in vital few Y = f(x1, x2, x3, x4, x5,……..xn) This s the function that models and quantifies the relationship between X & Y
Step 5 Improve Step 4 Analyse Step 3 Measure Step 2 Define Step 1 Recognition 6 Sigma Steps - RDMAIC • To find out vital causes (x) • Optimal value of causes • Verify optimal setting with set tolerances DOE is one of the tools used to establish relationship between inputs & outputs
Step 6 Control Step 5 Improve Step 4 Analyse Step 3 Measure Step 2 Define Step 1 Recognition 6 Sigma Steps - RDMAIC • Measurement System validation for inputs • Process capability • Implementation of SPC Charts
FMEA FMEA is an analytical technique used by designers, engineers and analysts to ensure that all design or manufacturing or process failure modes have been considered and are assessed with a view of elimination. • System FMEA • Process FMEA • Product/Design FMEA What is a failure? A component or system not meeting or not functioning as per design (Ex. Break failure) What is a failure mode? The manner in which a component or a system failure occurs (Ex. leakage of break oil ) What is an Effect? The impact or consequence of failure (vehicle meeting accident)
FMEA Degree of chances that it gets detected before it goes to customer • Severity of effect? (Scale 1-10) • Possibility of failure? (scale 1-10) • Possibility of detecting? (scale 1-10) Severity of impact Prob. of occurrence RPN (Risk Priority Number) Detectability 1. 8 4 2 64 (Max 1000, Min 1) 2. 4 9 216 6 Work on high RPN Reduce severity, rarely changes Reduce prob of occurrence (Have parallel system, hand break) Improve detectability (process, tests, reliability)
Y Importance y1 y2 y3 y4 y5 QFD Tool used priorities the areas to focus. Correlation between X’s H M L X1 X2 X3 X4 X5 3 2 6 5 2 4 3 4 4 Customer Requirements 3 2 2 3 7 1 3 1 1 5 1 57 32 56 Proj to focus
DOE Structured proactive process for finding relationship between input and output factors. Multiple input factors are considered and controlled simultaneously to ensure that the effect on the output is significant. • Why DOE? • To find out vital few Xs that influence the quality of Y • To identify the best combination of values of Xs to get the optimal value of process performance
Sigma level of different sectors Tax advice Prescription writing Restaurant bill Payroll processing 1000,000 Air Lines Baggage handling 100,000 10,000 Best in Class Air Lines safety 1000 Defects in PPM 100 10 1 2 3 4 5 6 7 1