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Six Sigma

Six Sigma. 6. Sam Tomas, CFPIM, CRM, C.P.M. Kokopelli. What is Six Sigma?. Number of Defects. Six Sigma is a reference to a particular goal of reducing defects to near zero.

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Six Sigma

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  1. Six Sigma 6 Sam Tomas, CFPIM, CRM, C.P.M. Kokopelli

  2. What is Six Sigma? Number of Defects • Six Sigma is a reference to a particular goal of reducing defects to near zero. • Sigma is the Greek letter“”that represents the “standard deviation” or variability of a group of items from their average value. • A Six Sigma program is therefore a variability reducing program. • The key objectives include improved processes, product performance, and reliability

  3. When a product is six sigma, it tells us that the quality level is excellent. What Else isSix Sigma? • A concept that provides a relatively new way to measure how good a product is. It relates to a manufacturing or service failure rate of only 3.4 rejects per millionoperations, or a yield of 99.99 99 99 8%.

  4. Why Six Sigma? • Why spend money to achieve six sigma quality when perhaps 99% or 98% perfect would be totally adequate? • The inadequacy of 99.9% accuracy can be illustrated as follows: • 22,000 checks will be deducted from the wrong bank accounts in the next 60 minutes • 880,000 credit cards in circulation will have incorrect cardholder information on their magnetic strips • 268,500 defective tires will be shipped this year • 18,322 pieces of mail will be mishandled the next hour • 14,208 defective computers will be shipped this year

  5. But With Six Sigma Quality - • Drug prescriptions • One incorrect drug prescriptions every 25 years. • Surgical operations • One incorrect surgical operation every 20 years • Mail Delivery • Only one article of mail lost every 35 years

  6. The Bathtub Curve • Shows reliability of a product in terms of failure rate per month • The curve presents two shaded areas • Latent defect rate • Causes early failure after a product is delivered • Inherent failure rate • Function of product design, materials, processes, and technologies used in manufacturing. • Defects in manufacturing are caused by: • Narrow design margins for the product • Insufficient manufacturing process controls • Poor incoming materials/parts quality

  7. I Infant Mortality II Useful Life III Wear out Latent Defects Overall Life Characteristic curve Failure Rate Inherent Failure Area Time Quality Failures due to Process & Material Wear out Failures Failure Rate Design-Related (Inherent) Failures Time The Bathtub Curve

  8. 6 Sigma Versus 4 Sigma • Why attempt to achieve 6 sigma when 4 sigma (99.9937%) may be adequate? • Even well controlled processes experience shifts in the mean as great as ± 1-1/2 standard deviations. • A normal 4 sigma process plus a 1-1/2 sigma shift in the process average would result in 4 sigma variations of 6,210 defects per million operations.

  9. Yield Rates ofSix Sigma Products • It is possible to build a product in which each component is a six sigma component and yet have the product exhibit yields of only 90%, 80%, 70%, 60% etc. • What we are talking about is rolled-throughput yield or the probability that all product, process and material characteristics will simultaneously conform to their respective standards.

  10. 3 66,810 dpm 10 X Improvement 4 6,210 dpm 30 X Improvement 5 223 dpm 70 X Improvement 6 3.4 dpm Improvement Efforts Required to Reach Six Sigma Dpm = defects per million

  11. Where are Average Companies in Quality? • Approximately 2 Sigma • IRS – Tax advice over the phone • Approximately 4 Sigma (Average) • Restaurant bills • Doctor prescription writing • Payroll processing • Order write-ups • Approximately 6 Sigma • Best in class – Seiko, HP Inc., etc. • 6.5 Sigma • Domestic flight fatality rate (0.43 ppm) 2 4 6 6.5

  12. Relationship of Defects to Other Factors • The 6 sigma concept indicates there are strong relationships between product “defects” and such factors as: • Reliability • Product yields • Cycle times • Inventories • Schedules • The higher the sigma value, the more reliable the process being monitored and the higher the improvement in all areas.

  13. Financial Implicationsof Low Sigma • The lower the sigma level, the higher the repair costs • A 4 sigma company spends more than 15% of its sales dollars forinternal and external repairs • A 6 sigma company spends about 1% • Over the long run, a 4 sigma company will not be able to compete with a 6 sigma company.

  14. What is the Cost of Quality? • Goal: Improve cost, quality, and schedule performance via process improvement and reduction of process variations. Note: Each sigma improvement represents a 10% net improvement in income.

  15. Design Process Material The Tools of Six Sigma • Design to standard parts/ materials • Design to standard processes • Design to known capabilities • Design for assembly • Design for simplicity • Parts standardization • Supplier SPC (SSPC) • Supplier certification • ERP/MRP • Process optimization • Process characterization • Process standardization • Short-cycle manufacturing • Statistical process control Region of Six Sigma Synergy

  16. Overcome Process Variation:First Strategy • Anticipate problems– develop controls during the design cycle for both the product and the manufacturing process steps to include the following: • Define 6 sigma tolerances on all critical product and process parameters • Minimize the total number of parts in the product • Minimize the number of process steps • Standardize on parts and procedures • Use SPC during initial design and prototype design phases

  17. Overcome Process Variation:Second Strategy • Use statistical process control(SPC)on the process to continually isolate, control and eliminate variation resulting from people, machines and the environment.

  18. Overcome Process Variation:Third Strategy • The third strategy addresses suppliers • Institute a supplier qualification program using SSPC techniques • Require suppliers to provide process control plans and process control charts • Minimize the number of suppliers used • Work towards a long term “win-win” partnership with all selected suppliers

  19. Five Steps to Six Sigma for Manufacturing • Identify product characteristics necessary to satisfy customers (Use QFD) • Determine if characteristics are controlled by part, process or both • Decide max allowed tolerance for correct performance • Determine existing process variations • Change product design, process, or both to attain the correct characteristics

  20. What Are Some Possible Applications for Six Sigma? • In the stockroom • Used to reduce parts counts that are found to be inaccurate • In personnel • Used to reduce the number of requisitions unfilled after 30 days • In customer service • Used to measure number of calls unanswered on the 2nd or 3rd ring • In sales • Used to track errors in completing order forms • In order fulfillment • Used to eliminate returns because of wrong product being shipped • In finance • Used to reduce the instances of accounts being paid after a specified time limit has elapsed

  21. Six Sigma Dilbert

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