הרצאה מס ' 10: תכן לאיכות , ניתוח כשלים, FMEA – Failure Mode and effects analysis

1. Technion – Israel Institute of TechnologyFaculty of Industrial Engineering and Management קורס תכן הנדסי ופיתוח מוצר סמסטר אביב תשע"ג הרצאה מס' 10: תכן לאיכות , ניתוח כשלים, FMEA – Failure Mode and effects analysis

2. מנגנוני כשל, עץ הכשלים ו-FMEA • תכן לאיכות (Design for Quality) • ניתוח כשלים בעזרת עץ הכשלים • ניתוח צורות הכשל והתוצאות

3. תכן לאיכות (Design for Quality) • השגת איכות המוצר המתאימה לשוק מתחילה מתהליך התכן. • איכות ניתן להשיג לא רק ע"י בחינת המוצר אלא מתוך תהליךהתכן ותהליך הייצור. • 80% מהכשלים מקורם בתכן לא מושלם. • הבסיס הכלל עולמי לתהליכי איכות בשלבי הפיתוח נתון ע"י סטנדרט DIN ISO 9000-8004.

4. תכן לאיכות (Design for Quality)(המשך...) • TQM (Total Quality Management) או TQC, מייצגיםתפיסה המבוססת על התיאוריה שניתן למנוע כשלים תוך כדי תהליך הפיתוח, ע"י מילוי מלא של דרישות הלקוחות. • למטרה זו פותח QFD, אשר מאפשר לתרגם דרישות הלקוח לדרישות מוגדרות היטב ומכומתות. • המטרה היא לזהות גורמי כשל אפשריים בדרך סיסטמטית ושיטות מניעה מוצעות. • תוצאות ניתוח מסוג זה מאפשרות לזהות נושאי איכות קריטיים במוצר שנמצא בשלבי פיתוח.

5. כשלים וגורמי הפרעה (Disturbing Factors) • תהליך התכן כולל שורה של צעדים יצירתיים ומתקנים, שיטות בחירה והערכה של פתרון, ניסויים ושיטות חישוב המאפשרים לזהות נקודות חולשה ולהוציאן מהתכן. • תקלות הן לא רק תוצאה של תכן כושל, אלא גם תוצאה של גורמי הפרעה. גורמי הפרעה יכולים להופיע כתוצאה של שינויים בנתוני כניסה (איכויות שונות של חומר גלם, שינויים באנרגיה וכו'). אם הגורמים האלה משפיעים על היציאה (output) יש צורך לדאוג להם ע"י שינוי בפתרון (תכן רובוסטי יותר או מערכת בקרה מתאימה).

6. כשלים וגורמי הפרעה (Disturbing Factors) • גורמי הפרעה חיצוניים כמו טמפרטורה, לחות, אבק ורעידות יכולים לגרום לתוצאות הרסניות. יש צורך לעצור את הופעת הגורמים בכדי למנוע את התפשטות הכשל. • דרישה מוקדמת למניעת כשלים וגורמי הפרעה היא לפחות לזהות ולהעריך כשלים אפשריים בשלב מוקדם ככל האפשר בתהליך הפיתוח של המוצר.

7. ניתוח בעזרת עץ כשלים (Fault Tree) • משלב של תכן קונצפטואלי, כל מתכנן יודע מה הפונקציה הכללית ותת-פונקציות שצריכות להתמלא. אז ניתן לשלול את הפונקציות אחת אחת, כלומר להניח שהפונקציות לא מתמלאות. • ניתן לפנות לפונקציות האלה ולחפש כל כשל אפשרי או הפרעות אשר יכולים לגרום לפונקציה מסוימת לא להתבצע. • ניתן לבחון אותם ע"י יחסים ו/או (and/or) של הכשלים האלה ותוצאותיהם. • המסקנות עוזרות למתכנן לשפר את התכן ואם יש צורך לבדוק מחדש את קונצפט הפתרון או לשנות ייצור, הרכבה, הובלה או תחזוקה.

8. דוגמת תכן שסתום • בדוגמה זו של שסתום בטחון (פריצה) של מיכל גז, נבחן את הכשלים האפשריים בשלב תכן קונצפטואלי.

14. Modes Effect Analysis(FMEA)

15. Learning Objectives To understand the use of Failure Modes Effect Analysis (FMEA) To learn the steps to developing FMEAs To summarize the different types of FMEAs To learn how to link the FMEA to other Black Belt tools To perform an exercise to actually perform an FMEA

16. What’s In It for Me? Allows us to identify areas of our process that most impact our customers Helps us identify how our process is most likely to fail Points to process failures that are most difficult to detect

17. Application Examples Manufacturing: A manager is responsible for moving a manufacturing operation to a new facility. He wants to be sure the move goes as smoothly as possible and that there are no surprises. Design: A design engineer wants to think of all the possible ways a product he is designing could fail so that he can build robustness into the product.

18. What Is A Failure Mode? • A Failure Mode is: • The way in which the component, subassembly, product, input, or process could fail to perform its intended function • Failure modes may be the result of upstream operations or may cause downstream operations to fail • Things that could go wrong

19. FMEA Evaluate Failure Modes and Effects What • Failure Modes & Effects Analysis is a methodology to evaluate failure modes and their effects in designs and in processes.

20. FMEA • Why • Methodology that facilitates process improvement • Identifies and eliminates concerns early in the development of a process or design • Improve internal and external customer satisfaction • Focuses on prevention • FMEA may be a customer requirement • FMEA may be required by an applicable Quality System Standard

21. FMEA Implementing FMEA • How • Team identifies potential failure modes for design functions or process requirements • They assign severity to the effect of this failure mode • They assign frequency of occurrence to the potential cause of failure and likelihood of detection • Team calculates a Risk Priority Number by multiplying severity times frequency of occurrence times likelihood of detection • Team uses ranking to focus process improvement efforts

22. FMEA Form Exercise Link

23. FMEA • A structured approach to: • Identifying the ways in which a product or process can fail • Estimating risk associated with specific causes • Prioritizing the actions that should be taken to reduce risk • Evaluating design validation plan (product) or current control plan (process)

24. When to Conduct an FMEA Early in the process improvement investigation When new systems, products, and processes are being designed When existing designs or processes are being changed When carry-over designs are used in new applications After system, product, or process functions are defined, but before specific hardware is selected or released to manufacturing

25. History of FMEA First used in the 1960’s in the Aerospace industry during the Apollo missions In 1974, the Navy developed MIL-STD-1629 regarding the use of FMEA In the late 1970’s, the automotive industry was driven by liability costs to use FMEA Later, the automotive industry saw the advantages of using this tool to reduce risks related to poor quality

26. The FMEA Form Identify failure modes and their effects Determine and assess actions Identify causes of the failure modes and controls Prioritize A Closer Look

27. Types of FMEAs Specialized Uses • Design • Analyzes product design before release to production, with a focus on product function • Analyzes systems and subsystems in early concept and design stages • Process • Used to analyze manufacturing and assembly processes

28. FMEA: A Team Tool Team Input Required • A team approach is necessary. • Team should be led by the Black Belt, a responsible manufacturing engineer or technical person, or other similar individual familiar with FMEA. • The following should be considered for team members: – Design Engineers – Operators – Process Engineers – Reliability – Materials Suppliers – Suppliers – Customers

29. FMEA Procedure Process Steps 1. For each process input (start with high value inputs), determine the ways in which the input can go wrong (failure mode) 2. For each failure mode, determine effects • Select a severity level for each effect 3. Identify potential causes of each failure mode • Select an occurrence level for each cause 4. List current controls for each cause • Select a detection level for each cause

30. FMEA Procedure (Cont.) Process Steps 5. Calculate the Risk Priority Number (RPN) 6. Develop recommended actions, assign responsible persons, and take actions • Give priority to high RPNs • MUST look at severities rated a 10 7. Assign the predicted severity, occurrence, and detection levels and compare RPNs

31. FMEA Inputs and Outputs Information Flow Inputs Outputs Brainstorming C&E Matrix Process Map Process History Procedures Knowledge Experience List of actions to prevent causes or detect failure modes History of actions taken FMEA

32. Failure Modes and Effects Failure – Effects Relationship Failure Mode 1 Effect 1 Failure Mode 2 Effect 2 Failure Mode 1 Effect 1 Failure Mode 2 Effect 1 Failure Mode 1 Effect 2 The relationship between failure modes and effects is not always 1 to 1.

33. Severity, Occurrence, and Detection • Severity • Importance of the effect on customer requirements • Often can’t do anything about this • Occurrence • Frequency with which a given cause occurs and creates failure modes • Detection • The ability of the current control scheme to detect or prevent a given cause

34. Rating Scales Assigning Rating Weights There are a wide variety of scoring “anchors”, both quantitative or qualitative Two types of scales are 1-5 or 1-10 The 1-5 scale makes it easier for the teams to decide on scores The 1-10 scale allows for better precision in estimates and a wide variation in scores (most common)

35. Rating Scales Assigning Rating Weights • Severity • 1 = Not Severe, 10 = Very Severe • Occurrence • 1 = Not Likely, 10 = Very Likely • Detection • 1 = Likely to Detect, 10 = Not Likely to Detect

36. Risk Priority Number (RPN) Calculating a Composite Score Severity X Occurrence X Detection = RPN • RPN is the product of the severity, occurrence, and detection scores.

37. FMEA Example Let’s Try Using FMEA • We will conduct an FMEA on the truck stop example we used to create a C&E Matrix • A Black Belt wants to improve customer satisfaction with the coffee served at the truck stop • The process map and completed C&E matrix follow

38. Truck Stop Coffee Process Map Process Map Outputs Inputs Outputs Inputs Complete Order Customer Order Size Specification Hot Water Soap Scrubber Cleaned Carafe Dirty Water Wet Scrubber Receive Coffee Order Clean Carafe Clean Carafe Cold Water Measuring Mark Full Carafe Fill Carafe w/Water Complete Order Hot Coffee Cup Filled Cup Pour Coffee into Cup Filled Maker Empty Carafe Full Carafe Customer Reply Amount Specified Complete Order Pour Water into Maker Filled Cup Customer Cream Sugar Amount Desired Offer Cream & Sugar Filter Maker w/Filter Place Filter in Maker Maker w/Filter & Coffee Maker w/Filter Fresh Coffee Dosing Scoop Put Coffee in Filter Complete Order Money Make Change Temperature Taste Strength Complete Transaction Operating Maker Heat Brewed Coffee Maker w/Filter & Coffee Turn Maker On Say Thank You Smile Happy Customer Coffee Delivery Hot Coffee Brewing Coffee Select Temperature Setting

39. Truck Stop Coffee C&E Matrix C&E Matrix We will focus on one of the two steps with the highest scores

40. Step 1: For Each Input, Determine the Potential Failure Modes Determine Failure Modes

41. Step 2: For Each Failure Mode, Identify Effects and Assign Severity Identify Effects and Severity

42. Step 3: Identify Potential Causes of Each Failure Mode and Assign Score Identify Failure Causes and Score

43. Step 4: List Current Controls for Each Cause and Assign Score Identify Controls and Score

44. Step 5: Calculate RPNs RPNs

45. Step 6: Develop Recommended Actions, Assign Responsible Persons, and Take Actions Identify Actions and Responsibilities

46. Step 7: Assign the Predicted Severity, Occurrence, and Detection Levels and Compare RPNs Compare RPNs

47. Summary Key Points • An FMEA: • Identifies the ways in which a product or process can fail • Estimates the risk associated with specific causes • Prioritizes the actions that should be taken to reduce risk • FMEA is a team tool • There are two different types of FMEAs: • Design • Process • Inputs to the FMEA include several other Black Belt tools