Measure Phase


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Measure Phase

  2. 2. Purposes of the Measure Phase <ul><li>To focus the improvement effort by gathering information about the current situation </li></ul><ul><li>To define one or more CTQ characteristics ( dependent variables),map the process in detail, evaluate the measurement systems, assess the current level of process performance to establish a baseline capability, the short and long term process sigma capabilities, and quantify the problem </li></ul>
  3. 3. Measure Phase Activities <ul><li>Most important tools used in the Measure Phase </li></ul><ul><ul><li>Process mapping </li></ul></ul><ul><ul><li>YX diagrams </li></ul></ul><ul><ul><li>Failure modes and effects analysis ( FMEA) </li></ul></ul><ul><ul><li>Measurement systems analysis ( MSA) </li></ul></ul><ul><ul><li>Capability analysis </li></ul></ul>
  4. 4. Measure Phase Activities <ul><li>Map the process in detail </li></ul><ul><ul><li>Process mapping helps a project team do the following: </li></ul></ul><ul><ul><ul><li>Describe how activities are being done </li></ul></ul></ul><ul><ul><ul><li>Understand the big picture </li></ul></ul></ul><ul><ul><ul><li>Identify how, when, or where a process should be measured </li></ul></ul></ul><ul><ul><ul><li>Investigate where problems might occur </li></ul></ul></ul><ul><ul><ul><li>Identify where modifications might best be made </li></ul></ul></ul>
  5. 5. Measure Phase Activities <ul><li>Map the process in detail </li></ul><ul><ul><li>A process map consists of flowcharts of the steps in a process– operations, decision points, delays, movements, handoffs, rework loops, and control or inspections </li></ul></ul><ul><ul><li>Mapping a process in detail should be an iterative process, as the team learns more about the process </li></ul></ul>
  6. 6. Measure Phase Activities <ul><li>Map the process in detail </li></ul><ul><ul><li>Process maps must identify forms of waste </li></ul></ul><ul><ul><ul><li>All wastes are influenced by and related to process bottlenecks and the inability of the process to flow smoothly </li></ul></ul></ul>
  7. 7. Measure Phase Activities <ul><li>A process map is a graphical representation of a process that is used to identify the following: </li></ul><ul><ul><li>All steps as value-added and non-value added </li></ul></ul><ul><ul><li>Key process inputs ( X’s) </li></ul></ul><ul><ul><li>Key process outputs ( Y’s) </li></ul></ul><ul><ul><li>Data collection points </li></ul></ul><ul><ul><li>First X’s to put into a FMEA </li></ul></ul><ul><ul><li>Cycle time per step </li></ul></ul>
  8. 8. Create a YX Matrix <ul><li>Takes information first identified in the process-mapping exercise and then documented through brainstorming methods like the cause and effect diagram </li></ul><ul><li>Method for quantifying and prioritizing the strength of the relationships between the input variables( X’s) and the output variables ( Y’s) </li></ul>
  9. 9. Create a YX Matrix <ul><li>Helps start thinking analytically about the process and facilitates buy-in for the solutions later </li></ul><ul><li>Key success factor in the use of the tool: team make-up </li></ul>
  10. 10. Create a YX Matrix <ul><li>Steps for creating a YX diagram: </li></ul><ul><ul><li>1- Call a team meeting and introduce the concepts of the YX diagram and assemble the list of potential X’s from the 3 sources: process mapping, brainstorming and preliminary data analysis </li></ul></ul><ul><ul><li>2- Enter the process name and revision date in the matrix information section </li></ul></ul>
  11. 11. Create a YX Matrix <ul><li>Steps for creating a YX diagram: </li></ul><ul><ul><li>3- Enter the Y’s deemed important by the team and/or customer </li></ul></ul><ul><ul><li>4- Score each Y from 1 to 10 </li></ul></ul><ul><ul><li>5- Enter all potential X’s felt to impact Y </li></ul></ul><ul><ul><li>6- Score the impact of each X on each Y </li></ul></ul><ul><ul><li>7- Analyze the results </li></ul></ul>
  12. 12. Create a YX Matrix <ul><li>YX Diagram: Priority compass to indicate where to start looking for the practical factors causing the defect </li></ul>
  13. 13. Failure Modes and Effects Analysis <ul><li>Technique allowing to study all possible problems in a process, the potential impact of each problem, and how to deal with each problem </li></ul><ul><li>FMEA starts with tribal knowledge, known defects, and current data collection </li></ul><ul><li>FMEA is not a tool to resolve the X’s that cause Y’s and eliminate X’s </li></ul>
  14. 14. Failure Modes and Effects Analysis <ul><li>Main steps for conducting an FMEA: </li></ul><ul><ul><li>List process functions ( steps) </li></ul></ul><ul><ul><li>List potential failure modes </li></ul></ul><ul><ul><li>List potential failure effects </li></ul></ul><ul><ul><li>Assign severity of each effect </li></ul></ul><ul><ul><li>List potential failure causes </li></ul></ul><ul><ul><li>Assign occurrence level to each cause </li></ul></ul>
  15. 15. Failure Modes and Effects Analysis <ul><li>Main steps for conducting an FMEA: </li></ul><ul><ul><li>List current process controls for the prevention / detection of failure modes </li></ul></ul><ul><ul><li>Assign detection levels to failure modes </li></ul></ul><ul><ul><li>Calculate the risk priority number </li></ul></ul><ul><ul><li>Specify recommended actions </li></ul></ul><ul><ul><li>Assign responsibility </li></ul></ul><ul><ul><li>Assign actions to be taken </li></ul></ul><ul><ul><li>Recalculate the risk priority number </li></ul></ul>
  16. 16. Failure Modes and Effects Analysis <ul><li>Description of some terms: </li></ul><ul><ul><li>SEV rating ( severity) ( 1 to 10): seriousness of the falure mode </li></ul></ul><ul><ul><li>OCC rating ( occurrence) ( 1 to 10): probability that failure mode will occur </li></ul></ul><ul><ul><li>DET rating ( 1 to 10): ability of controls to find the failure mode </li></ul></ul><ul><ul><li>RPN ( risk priority number): overall rating calculated by multiplying the 3 ratings: SEV, OCC and DET </li></ul></ul>
  17. 17. Failure Modes and Effects Analysis <ul><li>Practical rules for using an FMEA: </li></ul><ul><ul><li>An RPN greater than 80 is an indicator of a critical need for immediate action </li></ul></ul><ul><ul><li>A severity rating greater than 5 starts into safety-related defects </li></ul></ul><ul><ul><li>A high RPN with a low probability of detection P(DET) is likely to result in defects escaping internal tests and reaching customers </li></ul></ul><ul><ul><li>A high probability of occurrence is an indicator of poor capability </li></ul></ul>
  18. 18. Conduct a Measurement System Analysis <ul><li>If variation due to the process use of statistical process control to identify the sources and reducing that variation as much as possible </li></ul>
  19. 19. Conduct a Measurement System Analysis <ul><li>If variation due to the measurement system, errors can be classified into two categories: </li></ul><ul><ul><li>Accuracy: difference between recorded measurements and actual value for the parts measured </li></ul></ul><ul><ul><li>Precision: variation in measurements when a device is used to measure the same part repeatedly </li></ul></ul>
  20. 20. Conduct a Measurement System Analysis <ul><li>Accuracy: 3 components </li></ul><ul><ul><li>Stability: freedom from special cause variation over time </li></ul></ul><ul><ul><li>Bias: influence of any factor that causes the sample data to appear different from what it actually is </li></ul></ul><ul><ul><li>Linearity: statistical consistency in measurements over the full range of expected values </li></ul></ul>
  21. 21. Conduct a Measurement System Analysis <ul><li>Precision: 2 components </li></ul><ul><ul><li>Reproducibility: variation due to the measurement system </li></ul></ul><ul><ul><li>Repeatability: variation due to the measuring device </li></ul></ul>
  22. 22. Conduct a Measurement System Analysis <ul><li>Reproducibility and repeatability are the object of a specific study called a gauge repeatability and reproducibility study </li></ul><ul><ul><li>Can be performed on both attribute-based and variable-based measurement systems </li></ul></ul><ul><ul><ul><li>Attributes data: fit into categories that can be described in terms of words ( such as good or bad, pass or fail,..) and counted </li></ul></ul></ul><ul><ul><ul><li>Variables data: quantitative data consisting of discrete data that are counted and continuous data that are on a continuum, usually in decimal form </li></ul></ul></ul>
  23. 23. Determine the process capability <ul><li>Determine whether a process, given its natural short term variation, has the potential long term capability to meet established customer requirements or specifications </li></ul><ul><ul><li>A short term capability study covers a relatively short period of time and consists of 30 to 50 data points </li></ul></ul><ul><ul><ul><li>It measures the potential ( short term) capability of the process </li></ul></ul></ul><ul><ul><ul><li>This method of estimating sigma considers the variation within a subgroup </li></ul></ul></ul><ul><ul><ul><li>Does not consider the shift and drift between or among subgroups </li></ul></ul></ul>
  24. 24. Determine the process capability <ul><ul><li>A long term capability study covers a relatively long period of time and consists of 100-200 data points </li></ul></ul><ul><ul><ul><li>Measures the actual ( long term) capability of the process </li></ul></ul></ul><ul><ul><li>Total standard deviation says to estimate sigma considering the variation both within and between or among subgroups </li></ul></ul>
  25. 25. Determine the process capability <ul><li>A subgroup is a logical grouping of objects or events that displays only random event-to-event variations </li></ul><ul><ul><li>The objects or events are grouped to create homogenous groups free of assignable or special causes </li></ul></ul><ul><ul><li>By virtue of the minimum within-group variability, any change in the central tendency or variance of the universe will be reflected inthe subgroup-to-subgroup variability </li></ul></ul>
  26. 26. Conduct the Measure Phase- Gate Review <ul><li>The black belt reports to the executive team on the status of the project </li></ul><ul><li>To prepare for the review, the black belt and the champion should meet to discuss questions such as the following: </li></ul><ul><ul><li>What is the main problem? </li></ul></ul><ul><ul><li>How have you selected critical measures? </li></ul></ul><ul><ul><li>In what ways have you validated the measurement system? </li></ul></ul><ul><ul><li>What is the current process capability? </li></ul></ul>