【正文】 T Target A 3? Process 6? Overview Z Scale of Measure Z = A Unit of Measure Equivalent to the Number of Standard Deviations that a Value is Away from the Target Value Z Values USL LSL ?? ?? ??= Process Mean 181。 Note: Time is a Factor Only if Temperature Changes Significantly Step 9.....Establish Tolerances on “Vital Few” (Xs) How do we Ensure Oven Temperature is Controlled? ? Data Suggests 350 ( 5 ) is best Temperature to Reduce Taste Variation ? Brand A Flour to be Used Except in Case of Emergency ? “BETTER BREAD” to Search for Better Alternative Supplier of Flour Just in Case 176。6? Overview ? Six Sigma: A Definition Applied to GE GE Quality Initiative Why This Approach? Origin of Six Sigma The “Breakthrough Strategy” Arriving at Sigma ? Six Sigma Structure ? Key Concepts Tools ? A Practical Example An Overview....Not a lot of Details!! 6? Overview “ Six Sigma” ? If we can’t express what we know in the form of numbers, we really don’t know much about it. ? If we don’t know much about it, we can’t control it. ? If we can’t control it, we are at the mercy of chance. Mikel J. Harry President CEO Six Sigma Academy, Inc. A Rigorous Method for Measuring Controlling Our Quality “ ...will bring GE to a whole new level of quality in a fraction of the time it would have taken to climb the learning curve on our own.” John F. Welch, Jr. 1995 GE Annual Report 6? Overview What Does “Sigma” Mean? Sigma is a Measure of the Consistency of a Process It (???is Also the 18th Letter in the Greek Alphabet! Why Does GE Need A Quality Initiative? GE Raising The Bar – New Goal to be “Best in the World” vs. 1 or 2 – Customers are Expecting More, we Must Deliver – “Shipandfix” Approach no Longer Tolerated in the Market – Aim to Speed Past Traditional Competitors in 5 Years – Goal Consistent with Reduced Total Costs We Must Acknowledge Our Vulnerabilities ? Poor Quality That Impacts Customers ? Problems with NPI ? Too High Internal Costs 6? Overview We Need a Major Initiative to Move From Where we Are to Where we Want to be 6? Overview Why Does GE Need A Quality Initiative? 40% 35% 30% 25% 20% 10% 15% 5% Cost of Failure (% of Sales) Defects per Million 233 6210 66,807 308,537 500,000 Sigma 6 5 4 3 2 1 Estimated Cost of Failure in US Industry is 15% of Sales。 177。 The Potential Performance of a Process, Corrected for an OffTarget Mean LSL USL ?? ?? ??Process Mean 181。 Z T Target 0 A 3? Process The Definitions of Yield Final Test Process (Process 4) Pass Process 3 Process 1 Process 2 100 (Units Tested) 65 70 82 91 Yield 1 Yield 2 Yield 3 Loss 1 Loss 3 Rejects Loss 2 9 9 12 5 ? First Time Yield (Yft) = Units Passed Units Tested = 65 70 = ? Rolled Thruput Yield (Yrt) = (Yield 1) (Yield 2) (Yield 3) . . . . = 91 82 65 70 ( ( ( ( ) ) ) ) = 100 91 70 82 ? Normalized Yield (Ynm) = = 1/n (Yrt) () 1/4 = ( n: Total Number of Processes ) 6? Overview Yield Exclusive of Rework Probability of Zero Defects Average Yield of All Processes 6? Overview The Impact of Complexity Rolled Yield Number of Operations .4 .1 1 10 100 1,000 10,000 1,000,000 Process Mean Centered on Each Operation 1 10 100 1,000 10,000 1,000,000 Rolled Yield Number of Operations .5 As the Number of Operations Increases, a High Rolled Yield Requires a High ??for Each Operation 5?? 4?? 3?? 6?? 6?? 5?? 4?? 3??Process Mean Shifted ??at Each Operation 6? Overview Baselining Benchmarking an Existing Process p (x) Defects Benchmark Baseline Entitlement ? Benchmark.....A WorldClass Performance ? Entitlement.....Achievable Performance Given the Investments Already Made ? Baseline.....The Current Level of Performance Baselining = Current Process / Benchmarking = Ultimate Goal Some Basic 6?Related Tools 6? Overview Scatter Diagram Over Slept Car Would Not Start Weather Family Problems Other Pareto Diagram Frequency of Occurence Reasons for Being Late for Work Arrival Time at Work Time Alarm Went Off Materials People The Histogram Control Charts 6? Overview Some Basic 6?Related Tools The Fishbone Diagram Measurements Methods Technology Statement Cause Effect Being Late for Work Plot of Daily Arrival Time 9:15 7:00 7:15 7:30 7:45 8:00 8:15 8:30 8:45 9:00 Average Value Number of People Arriving at CRD Time 6? Overview LCL UCL Range Chart R Out of Control Condition LCL X UCL X Bar Chart Some Basic 6?Related Tools LCL = Lower Control Limit UCL = Upper Control Limit X = Mean R = Average Range Monitors Changes in Average or Variation Over Time Design of Experiments 6? Overview SCREENING OPTIMIZATION CHARACTERIZATION