1. Dave Dortman 920-207-1648 ddortman@yahoo.com Rolled Throughput Yield (RTY) Six Sigma Black Belt Presentation

2. Define Measure Analyze Improve Control What do we need to know about RTY? What is RTY and why is it important? The “Hidden Factory” How to calculate RTY How to estimate RTY using e -dpu 2

3. Define Measure Analyze Improve Control Rolled Throughput Yield (RTY) is the product of the observed yields from each step in a process. It is the probability of a unit passing through all steps of a process and incurring no defects. RTY shows the effect of variation on both rework and scrap. Rework is known as the “Hidden Factory.” What is Rolled Throughput Yield? 3

4. Define Measure Analyze Improve Control The Hidden Factory AKA “Classic Yield” 4 Rework Scrap OperationInspection N S Rework “The Hidden Factory” Classic Yield does not account for rework

5. Define Measure Analyze Improve Control Rolled Throughput Yield (RTY) Calculations 5 Inspection Rolled Throughput Yield, RTY: Rework N S Scrap OperationInspection Rework Scrap Operation FPY includes no defects Rework accounts for differences between Classic Yield and RTY

6. Define Measure Analyze Improve Control Rolled Throughput Yield (RTY) 6 Receiving Inspection: First Pass Yield #1 = 0.955 Machining Operations: First Pass Yield #2 = 0.970 Finishing Operations: First Pass Yield #3 = 0.944 RTY = FPY 1 x FPY 2 x FPY 3 RTY = 0.955 x 0.970 x 0.944 = 0.875 RTY = FPY 1 x FPY 2 x FPY 3 RTY = 0.955 x 0.970 x 0.944 = 0.875 Parts Receiving For every 1,000 parts received, only 875 reach this point without rework Dollars lost to rework and scrap

7. Define Measure Analyze Improve Control Measures the percent of product that goes through the process without being scraped or reworked. Reworks within an operation have no value and comprise what is termed “The Hidden Factory!” Is the yield calculated below a RTY? Yield = Amount of Material Exiting Process Amount of Material Entering Process No! It is an overall yield of scrapped product, it ignores rework. Why is RTY important? 7

8. Define Measure Analyze Improve Control Defective Units versus Defects per Unit If you can count the number of defective units after each process step, then you can calculate RTY as RTY = FPY 1 x FPY 2 x FPY N N = number of process steps If you can only count the number of defects after each step, then you must estimate the Frist Pass Yield using the Poisson approximation FPY = e -dpu where dpu is the average defect per process step 8

9. Define Measure Analyze Improve Control Rationale for e -dpu Based on the Poisson distribution Y = e –dpu “e” is a constant 2.718281828… The natural log (ln) of this constant is 1. If the number of defects per unit is known, RTY can be calculated. 9 Mr. Poisson

10. Define Measure Analyze Improve Control e -dpu provides a good approximation! YieldDPU 0.9550.045 0.970.03 0.9440.0565 Total DPU0.131 RTY 87.72% 10 RTY = FPY 1 x FPY 2 x FPY 3 RTY = 0.955 x 0.970 x 0.944 = 87.45% RTY = FPY 1 x FPY 2 x FPY 3 RTY = 0.955 x 0.970 x 0.944 = 87.45% Y = e –dpu Y = Yield e = 2.718281828… dpu = defect per unit In Microsoft Excel, the EXP function returns e raised to the nth power, where e = 2.71828183.

11. Define Measure Analyze Improve Control Braun is Batting.500 !!! 11 If Braun is batting.500 what does that mean? What would a RTY of 50% indicate? Answer: 50% of product made it through the process without being scrapped or reworked. If RTY = 50%, how much product would be scrapped versus reworked? Answer: We don’t know just from the single RTY number.

12. Dave Dortman 920-207-1648 ddortman@yahoo.com Questions ???

13. Define Measure Analyze Improve Control Variation, Rework, and Scrap 13 The goal of Six Sigma is to eliminate rework and scrap by eliminating variation!