Six Sigma quality (3.4 defects per million units produced) is probably a bit much to ask of Rachel’s old oven (see problem 2).
a. What would the standard deviation in the temperature of her oven need to be if she settled for a “Three Sigma” level of quality?
b. If her oven exactly meets a “Three Sigma” quality level, what percentage of the time would her oven be operating at a temperature outside the acceptable range?
(See Table 6-5.)

DATA FROM PROBLEM 2:

Cost item Total for the Year

Quality assurance.................................................................... $450,000
Equipment maintenance........................................................ $205,000
Product redesign..................................................................... $310,000
Product warranty and repair................................................. $550,000
Product testing and inspection............................................. $372,000
Training..................................................................................... $250,000
Process improvement/Kaizen................................................ $120,000
Material scrap........................................................................... $230,000
Rework labor............................................................................ $426,000
Incoming materials inspection............................................... $323,000
Customer support (after sale)................................................ $150,000
Travel to suppliers/process certification................................ $ 75,000
Travel to customers/problem solving..................................... $ 80,000

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TABLE 6-5 How Quality Relates to Sigma Sigma Level 20 ب الله За 40 50 60 The Classical View of Quality "99.9% Good" (4.60) • 20,000 lost articles of mail per hour. • Unsafe drinking water almost 15 minutes each day. •5,000 incorrect surgical operations per week. • 2 short or long landings at most major airports daily. • 200,000 wrong drug prescriptions each year. • No electricity for almost 7 hours each month. Defects per Million Units 308,770 66,810 6,209 233 3.4 The Six Sigma View of Quality "99.99966% Good" (60) . • Seven lost articles of mail per hour. • One minute of unsafe drinking water every seven months. • 1.7 incorrect surgical operations per week. • One short or long landing at most major airports every five years. • 68 wrong drug prescriptions each year. . One hour without electricity every 34 years.