Six sigma, spc , lean

Techniques of Quality and Control Assurance
Six Sigman, SPC and Lean

1. Six Sigma | SPC Techniques | Lean Metrology & Quality Assurance Mechanical Engineering Department

2. Six Sigma 2

3. SIX SIGMA

4. Table of Contents Six Sigma History of Six Sigma 6 Sigma Key Concept Example Six Sigma Methodologies Levels of Six Sigma Other Statistical Analysis Tools 4

5. Six Sigma The term “Six Sigma” refers to the notion that if you have six standard deviations between the mean and the nearest specification limit, practically nothing will exceed the limits. 5

6. History of Six Sigma Initially developed at Motorola by Bill Smith in 1986 Used old concepts and combined them Way of measuring defects and improving quality New methodology for reducing defects below 3.4 DPMO (defects per million opportunities 6

7. History of Six Sigma Motorola claims over $17 billion in savings that can be attributed to Six Sigma as of 2006 Many companies since Motorola have also adapted Six Sigma General Electric Bank of America Caterpillar Honeywell 3M Amazon.com Boeing Whirlpool 7

8. Six Sigma Key Concepts Critical to Quality Attributes most important to the customer Defect Failing to deliver what the customer wants Process Capability What your process can deliver 8

9. Six Sigma Key Concepts Variation What the customer sees and feels Stable Operations Ensuring consistent, predictable processes to improve what the customer sees and feels Design for Six Sigma Designing to meet customer needs and process capability 9

10. About the Term Six Sigma Standard Deviation Degree of dispersion from mean value Where, s = standard deviation X = data point M = average of all data points n = population 10

11. About the Term Six Sigma 11

12. About the Term Six Sigma Six Sigma= Near Perfection! 12

13. Examples of Six Sigma GE’s 6σ implementation Began in 1995 across entire organization Saved $320 million in first 2 years, $1 billion by 1999. It is not a secret society, a slogan or a cliché. Six Sigma is a highly disciplined process that helps us focus on developing and delivering near-perfect products and services. 13

14. Example of Six Sigma Geico: 97% customer satisfaction 4σ USPS: 95% 1st class mail delivered on time 3 σ Six Sigma can be applied to any industry, service, or approval rating 14

15. Six Sigma Methodologies Two key methodologies DMAIC Used for improving existing processes DMADV Used for creating new product/process designs Used for already optimized processes (with DMAIC or another method) that still fall short of expectations 15

16. D M A I C 16

17. DMAIC DMAIC stands for: D Define M Measure A Analyze I Improve C Control 17

18. DMAIC : Define Define process improvement goals Why the 6σ program is in place? Define customers needs Need vs. requirements to fulfill need Create high level process map 18

19. DMAIC : Measure Measure current process and collect relevant data Develop data collection plan Collect data from many sources to determine types of defects Compare to customer surveys Determine shortfalls 19

20. DMAIC : Measure Determine unit, defect, opportunity Unit = Value of process, input, or output Defect = Something wrong with a unit Too large Too small Not equal to Opportunity = Way to fix the defect 20

21. DMAIC : Measure Find the baseline σ Defects / Million opportunities = Number of Defects x 1,000,000 Number of Units x Number of Opportunities 21

22. DMAIC : Analyze Analyze data collected Identify gaps between current performance and goal performance Determine root causes of defects Sources of variation Look for opportunities for improvements Prioritize them 22

23. DMAIC : Analyse Example: Grocery Store Horizontal bar graph showing percentages of defect occurrences 23

24. DMAIC : Analyse Process analysis Subprocess Mapping Start with High Level Process Map from Define phase Reduce or eliminate inefficient steps Analyze map for non-value added steps Categorize non-value added steps Root cause analysis Determine cause of defects Open Brainstorm all explanations of current sigma process Narrow Consolidate similar ideas and vote on most likely causes Close 24

25. DMAIC : Improve Create innovative solutions to fix and prevent problems using technology and discipline Create a solution for each verified root cause Select solutions Implement solutions either individually or in groups Recalculate sigma for each implementation 25

26. D M A D V 26

27. DMADV DMADV stands for: D Define M Measure A Analyze D Design V Verify 27

28. DMADV- Design Design details Optimize design Run simulations if necessary Prepare for design verification 28

29. DMADV- Verify Verify design Set up pilot runs Implement process Train process owners Hand over to process owners 29

30. Levels of Six Sigma Yellow Belt Trained in Six Sigma techniques as part of a corporate-wide initiative Have not completed a Six Sigma project Not expected to use Six Sigma actively for quality improvement projects. 30

31. Levels of Six Sigma Green Belt Focuses on 1-2 projects, part time Have other job responsibilities Direction comes from Black Belt Skilled at project management Responsible for project progress Lead planning teams 31

32. Levels of Six Sigma Black Belt Focuses on 1-3 projects Full time Has specific projects Focus on project execution Direction comes from Master Black Belt 32

33. Levels of Six Sigma Expert Used primarily in Aerospace and Defense Business Sectors Work across company boundaries Work at many different sites Improve services, processes, and products Not all companies have this level 33

34. Levels of Six Sigma Master Black Belt Identified by Champions Act as an in-house expert coach for Six Sigma Supports many improvement teams, not limited to a certain number of projects Recruits and trains other Black Belts and Green Belts Deploy Six Sigma across various functions and departments 34

35. Levels of Six Sigma Champion Usually senior manager Driving force behind organization’s 6σ implementation Mentor to other Black Belts At some companies, may be known as “Quality Leader” 35

36. Levels of Six Sigma Executive Leadership CEO and other top management Set up vision for Six Sigma Choose Champions 36

37. Criticism on Six Sigma Article in Fortune that claims "of 58 large companies that have announced Six Sigma programs, 91 percent have trailed the S&P 500 since.“ and that Six Sigma is effective at what it is intended to do, but that it is "narrowly designed to fix an existing process" and does not help in "coming up with new products or disruptive technologies." 37

38. Criticism on Six Sigma Hard to get things done with 6σ 6 is an arbitrary number Not necessary for some companies, good for others, not acceptable for some i.e. medical supplies versus direct mail advertising campaign Home Depot attempted to use Six Sigma but led to frustration for employees and customers – employees required to help 22.8 customers per hour instead of 13.4 Basis for choosing 6 for the number of standard deviations is never clearly explained Along with the 1.5σ shift 38

39. Statistical Process Control (SPC) 39

40. Table of Contents Definition Importance of SPC Quality measurement in manufacturing Statistical control charts Introduction Types of variation Control charts Process capability Basic Definition. Use of process capability information. Standardized formula. Relationship to product specification. The capability index. 40

41. Definition Statistical process control as the application of statistical method to the measurement and analysis of variation in a process. This techniques applies to both in-process parameter and end-of-process parameters. A process is a collection of activities that converts inputs into outputs or result. More specifically a process is a unique combination of machine, tools, methods, materials and people that attain an output in goods, software or services. 41

42. Importance of SPC Reduces waste Reduction in the time which is required to produce the product. Detecting error at inspection. Reduces inspection cost. Saves cost of material by reducing number of rejects. More uniform quality of production. Customer satisfaction. It provides direction for long term reduction in process variability. It is stable process and operates with less variability. 42

43. Quality Measurement in Manufacturing Quality measurement is central to the process of quality control: “what gets measured, gets done.” Measurement is basic for all three operational quality process and for strategic management Quality control measurement – provides feedback and early warnings of problems. Operational quality planning measurement – quantifies customer needs and product and process capabilities. Quality improvement measurements – can motivate people, prioritize improvement opportunities, and help in diagnosing causes. 43

44. Statistical Control Charts A statistical control chart compares process performance data to computed ‘statistical control limits’ drawn as limit lines on the chart. Prime objective of control chart is – detecting special causes of variation in a process by analysing data from both the past and the future Process variations have two kinds of causes Common (random or chance) Special (assignable) 44

45. Types of Variation Two kinds of variation occur in all manufacturing processes Common Cause Variation or Random Cause Variation consists of the variation inherent in the process as it is designed. may include variations in temperature, properties of raw materials, strength of an electrical current etc. Common cause is the only type of variation that exist in the process and process is said to be ‘in control’ and stable Special Cause Variation or Assignable-cause Variation With sufficient investigation, a specific cause, such as abnormal raw material or incorrect set-up parameters, can be found for special cause variations. Special cause variation exist within the process and process is said to be ‘out of control’ and unstable 45

46. Types of Variation SPC control chart is one method of identifying the type of variation present. Statistical Process Control (SPC) Charts are essentially: Simple graphical tools that enable process performance monitoring. Designed to identify which type of variation exists within the process. Designed to highlight areas that may require further investigation. Easy to construct and interpret. 2 most popular SPC tools Run Chart Control Chart SPC charts can be applied to both dynamic processes and static processes 46

47. Control Charts Show the variation in a measurement during the time period that the process is observed. changes to the process. This information is then used to make quality improvements. A time ordered sequence of data, with a centre line calculated by the mean. Used to determine the capability of the process. Help to identify special or assignable causes for factors that impede peak performance. 47

48. Control Charts 48

49. Control Charts Control limits define the zone where the observed data for a stable and consistent process occurs virtually all of the time (99.7%). Any fluctuations within these limits come from common causes inherent to the system, such as choice of equipment, scheduled maintenance or the precision of the operation that results from the design. An outcome beyond the control limits results from a special cause. The automatic control limits have been set at 3-sigma limits. 49

50. Control Charts The area between each control limit and the centerline is divided into thirds . Zone A - "1-sigma zone“ Zone B - "2-sigma zone" Zone C - " 3-sigma zone “ 50

51. Types of Control Charts The are two types of charts: Variable Charts R- Chart X- Chart 2. Attributed Charts P- Charts C - Charts 51

52. Variables Charts Variable data are measured on a continuous scale Ex: time, weight, distance or temperature can be measured in fractions or decimals Applied to data with continuous distribution A ttribute Charts Attribute data are counted and cannot have fractions or decimals. Attribute data arise when you are determining only the presence or absence of something: success or failure, accept or reject, correct or not correct. Ex: A report can have four or five errors but it cannot have four and half errors. Applied to data following discrete distribution 52 Types of Control Charts

53. R - Charts It controls the dispersion of the process R is the range or difference between the highest and lowest values in sample It measures gain or loss of uniformity within a sample which represents the variability in the response variable over time. Ex: Weigh samples of coffee and computes ranges of samples Plot X - Charts It controls the central tendency of the process Shows sample means over time Monitors process average Example: Weigh samples of coffee and compute means of samples; Plot 53 Types of Control Charts

54. P - Charts It tracks the proportion or percent of nonconforming units or percent defective in each sample over time. Ex: Count defective chairs & divided by total chairs inspected Chair is either defective or not defective C - Charts It shows the number of nonconformities i.e defects in a unit Unit may be chair , steel sheet , car etc. Size of unit must be constant Ex: Count defects (scratches .chips etc.) in chair of a sample of 100 chairs 54 Types of Control Charts

55. Advantages of Statistical Control Provides means of detecting error at inspection. Leads to more uniform quality of production. Improves the relationship with the customer. It reduces cost. It reduces the number of rejects and saves the cost of material. It determines the capability of the manufacturing process It provides direction for long term reduction in process variability. It is stable process and operates with less variability. 55

56. Process Capability Process capability studies distinguish between conformance to control limits and conformance to specification limits (also called tolerance limits) if the process mean is in control, then virtually all points will remain within control limits staying within control limits does not necessarily mean that specification limits are satisfied specification limits are usually dictated by customers 56

57. Use of Process Capability Information Predicting the extent of variability that process will exhibit. Choose most appropriate process to meet the tolerance. Planning the inter-relationship of sequential process. Assign the machines to work for which they are best suited. Testing causing of defect during quality improvement programs. 57

58. Standardized Formula The most widely used formula for process capability is Process Capability = ± 3σ Where, σ = Standard deviation of the process If the process is centered and follows normal probability within ± 3σ of the normal specification. 99.37% product will fall 58

59. Capability Index ( CPK ) Cp index measures potential capability, assuming that the process avg. is equal to the mid point of the specification limit and the process is operating in statistical control because the avg. often not at the mid point it is useful to have capability index that reflects both variation and the location of the process avg. Such index is the capability index ( Cpk ) . 59 C pk = [ Upper Specification limit – x ] or 3  [ x - Lower Specification Limit ] 3  Where, x  process mean   standard deviation of the process population

60. Capability Index ( CPK ) If actual avg. = mid point of the specification range Cpk = Cp Higher the Cp lower the amount of product outside specification limit. A capability index can also be calculated around a target value rather than actual avg. This index called as Taguchi index ( Cpm ). Krishnamoorti & Khatwani (2000) propose capability index for handling normal and non- normal characteristic . 60

61. Assumption of Statistical Control & Its Effect on Process Capability There are five key assumption Process Stability:-statistical validity requires a state of statistical control with no drift or oscillation. Normality of the characteristic being measured :-Normality is needed to draw statistical interference about the population. Sufficient Data :-It is necessary to minimize the sampling error for the capability index. Representativeness of samples :- must include random sample. Independence of measurements:- Consecutive measurement cannot be correlated. Are not theoretical refinements they are important condition for applying capability index . 61

62. LEAN 62

63. Table of Contents What is lean? Why lean? Principles of lean Goals of lean Types of waste Lean tools Steps to achieve lean systems 63

64. What is Value? Value - A capability provided to a customer at the right time at an appropriate price, as defined by the customer. Cost Quality Delivery 64

65. What is Waste? Waste is any activity that consumes time, resources, or space but does not add any value to the product or service . 65

66. Constraints on Performance Improvement Lack of Funds 43% Limited Resources 42% Lack of Time 40% Lack of Qualified Personnel 32% 66

67. 5 Principles of Lean Define value from the customer perspective Identify the value stream Make the process flow Pull from the customer Head toward perfection 67

68. 5 Principles of Lean Specify value : Specify value from the standpoint of the end customer by product family. Identify the value stream : Identify all the steps in the value stream for each product family, eliminating whenever possible those steps that do not create value. 68

69. 5 Principles of Lean Create flow : Make the value-creating steps occur in tight sequence so the product will flow smoothly toward the customer. Let the customer pull product through the value stream: Make only what the customer has ordered. 69

70. 5 Principles of Lean  Seek perfection : As value is specified, value streams are identified, wasted steps are removed, and flow and pull are introduced, begin the process. and continue it until a state of perfection reached in which perfect value is created waste. 70

71. Four Goals of Lean Improve quality: In order to stay competitive in today’s marketplace, a company must understand its customers' wants and needs and design processes to meet their expectations and requirements. Eliminate waste: Waste is any activity that consumes time, resources, or space but does not add any value to the product or service. 71

72. Four Goals of Lean Reduce time: Reducing the time it takes to finish an activity from start to finish is one of the most effective ways to eliminate waste and lower costs. Reduce total costs: To minimize cost, a company must produce only to customer demand. Overproduction increases a company’s inventory costs due to storage needs. 72

73. The Seven Forms of Waste overproduction (occurs when production should have stopped) Waiting (periods of inactivity) Transport (unnecessary movement of materials) Extra Processing (rework and reprocessing) Inventory (excess inventory not directly required for current orders) Motion (extra steps taken by employees due to inefficient layout) Defects (do not conform to specifications or expectations) 73

74. The Seven Forms of Waste Overproduction : Producing more/sooner than the Internal or External customer needs. Waiting : Long periods of inactivity for people, information, machinery or materials . Transportation : Excessive movement of people, information or materials. 74

75. The Seven Forms of Waste In appropriate processing: Using the wrong set of tools, procedures or systems. Unnecessary Inventory: Excessive storage and delay of information or products. 75

76. List of Lean Tools waste elimination standardized work poka yoke 5s visual workplace just in time continuous improvement material management work in process 76

77. POKA - YOKE POKA-YOKE- means “Mistake proofing”. And it also provides visual or other signals to indicate characteristic state and referred as error proofing . It is a Japanese word . 77

78. 5S Visual Work Place POKA-YOKE- means “Mistake proofing”. And it also provides visual or other signals to indicate characteristic state and referred as error proofing . It is a Japanese word . 78

79. Just in Time It can lead to huge improvements in quality and efficiency . This method was adopted by Japanese manufacturing company. JIT means making what the market wants, when it want it. 79

80. Continuous Improvements Continuous improvement ,in regards to quality and performance . And it also improves customers satisfaction through continuous and incremental approach. And there by removing unnecessary activities and variation . 80

81. Work in Process It aims to minimize the work . It needs to store the inventory . It take time to look above and below work areas for needed storage . 81

82. Material Management It is a branch of logistics and deals with tangible components of supply chain. It can consolidate and efficiently handle core service . The parts and materials used in supply chain meets the minimum requirements by performing quality assurance . 82

83. Value Stream Mapping Lean Thinking diagnostic tool that allows you to: Visualize work “See the waste” (barriers to flow) Focus on improvements Value Stream = steps (value added and non-value added) that are required to complete a service from beginning to end 83

84. Value Added VS Non-Value Value added activities The customer is willing to pay money for the process Work that changes the market form, fit or function Non-value added activities Should be eliminated, simplified, reduced, or integrated whenever possible Two types of non-value added activities: Required for business Not required for busines s 84

85. Value Added VS Non-Value Continuous focus on increasing value added activities If value added activities are increased by 10% = gain of only 2%! Focus on reducing non-value added activities by 10% = gain of 8% value added! 85 Non-Value Added 80% Value Added

86. Design a Simple Manufacturing System There is always room for improvement The core of lean is founded on the concept of continuous product and process improvement and the elimination of non-value added activities. “The Value adding activities are simply only those things the customer is willing to pay for, everything else is waste, and should be eliminated, simplified, reduced, or integrated”. Improving the flow of material through new ideal system layouts at the customer's required rate would reduce waste in material movement and inventory. Continuously improve A continuous improvement mindset is essential to reach a company's goals. The term "continuous improvement" means incremental improvement of products, processes, or services over time, with the goal of reducing waste to improve workplace functionality, customer service, or product performance. 86

87. Design a Simple Manufacturing System A fundamental principle of lean manufacturing is demand-based flow manufacturing. In this type of production setting, inventory is only pulled through each production centre when it is needed to meet a customer’s order. The benefits of this goal include decreased cycle time less inventory increased productivity increased capital equipment utilization 87

88. Thank You A LI RAZA [phone] [email protected] 2 017-ME-516 88