The materials required over the next two modules include:

Transcription

1 Meet with the Math Instructor and verify that the statistics modules have been completed and that students will be again reviewing these kinds of data over the next two quality modules. The Math Instructor may want to re-address these math functions using the Quality Modules worksheets/exercises. Also, meet with the Communications Instructor before sessions 3 & 4 and suggest attending part or all of those sessions so the Communications Instructor can understand the concepts and how to help students complete the assignments. The materials required over the next two modules include: - Blank graph paper for Pareto Analysis - Blank Cause/Effect diagram (available in the Quality Mfg Materials packet at: ftp://ctweb.hfcc.net/nsf/) - Blank attribute chart - Blank X-bar control chart (available in the Quality Mfg Activities Mod4 Activity3: ftp://ctweb.hfcc.net/nsf/) - cientific calculator (Texas Instruments TI-30Xa or equivalent) - PC manual from AIAG as 8HFCC MODULE 3-1

2 reference (has formulas and values for variables used in same). Packet from Lou Goderis (use in both Module 3 & 4) Focus: In the next two modules we will review the standard basic shop floor PC tools and become familiar with their use and the kinds of analysis done with them. Be ready to graphically show some of the terms in Activity 1 either on the flip charts or by distributing in advance both control charts (attribute and X- bar) that students will use. ome Bridge students may have prior experience working with these kinds of tools. Think About It: How can quality be measured in more specific terms than satisfied customers or no rejects? Have you ever wondered how companies process all those comment cards that are filled out by customers, guests, patients? In quality terminology what does out of control mean? 8HFCC MODULE 3-2

3 ession Activities/Outcomes: During these two four-hour sessions you will: 1. Review the definitions of terms related to PC. 2. Discuss a manufacturing process in terms of stability and capability. 3. Using an instructor-supplied problem, analyze data and create a Pareto diagram. 4. Based on previous activity and data, create a Cause and Effect (problem) diagram with a neighbor. You will volunteer possible causes of the problem for class brainstorming. 5. Using instructor-supplied data and form, create and interpret an Attributes Control Chart (P-chart only). You will use the terms previously discussed to describe the results. Discuss the results first with your neighbor and then with the class for consensus. Terms to be reviewed include attribute data, brainstorming, capable process, Cause and Effect diagram, control charts, Cpk, out-of-control process, LCL, LL, over-correction, overadjustment, Pareto Analysis, P- bar and P-chart, range, sigma, stable process, target (nominal), UCL, UL, variables data, WCM and X-bar. 6. Create and interpret a Variables Control Chart (X-bar chart only). You will use the terms previously discussed to describe the results. Discuss the results first with your neighbor and then with the class for consensus. Activity 1 Quality Manufacturing Terms - Attribute data (see also Control Charts). 8HFCC MODULE 3-3

4 - Brainstorming Commonly used to describe data that is counted or that has appearance / cosmetic characteristics. Example: the number of car hoods with scratches, or percentage of hoods with defects (P-chart). ee Control Charts. Brainstorming is a method used to start team problem-solving, or a way to create discussion and sometimes build synergy. Requires the following: Non-judgment from fellowstudents and team members, e.g., that s a stupid idea/statement is not acceptable Openness pontaneity Everyone participates Documentation of ideas presented. - Capable process (see also stable process ) - Cause and Effect diagram Reference the way you have used the flip chart. A capable process is one that is capable of making product that meets specifications or requirements. Readings on a control chart, if all displayed, are within the UL and LL. Typically measured through a calculation called Cpk (refer to other definitions). 8HFCC MODULE 3-4

5 - Control Charts (see also Attribute Data ) Cpk (see also WCM ) Lower Control Limit (LCL) A cause and effect diagram is also known as a feather, Ishikawa or Fishbone diagram (due to its shape). Reference Module 2 Japanese quality pioneers, A cause and effect diagram is a graphic representation ( painting ) of a process with plotted data points and connecting lines. It needs interpretation and/or reaction once points are plotted (daily for example). There are 4 types of attribute control charts and 4 types of variable control charts. We only teach one type each in this course due to time constraints. Refer students to the reference manual mentioned at the start of this module for further explanation. Cpk is a calculation expressed as a number. If the calculated Cpk is < 1.0, a company is pumping out garbage or rejects. The WCM goal or value is 2.0. Cpk is the lesser of 2 calculations. Explain the formula when appropriate (Module 4, activities 4 & 5). For automotive companies the minimum Cpk value is The Lower Control Limit is a line labeled on a control chart that identifies the lower acceptable data threshold. Ideally you want 8HFCC MODULE 3-5

6 Lower pec(ification) Limit (LL) Out-of-control process Over-adjustment Over-correction Percentage chart (P-chart) both the LCL and UCL to be located within the specification limits (LL and UL). Lower pecification (pec) Limit, a number provided by the customer which indicates the lowest reading identified by the customer as acceptable. However, one should not believe that parts that are produced at the low or high end of the tolerance are equal in performance to those close to the target. A process that is out-of-control may display numerous calculated points on the control chart beyond (outside) the UCL or LCL. One or two points beyond the control limits is not usually cause for alarm. Over-adjustment means unnecessary adjustments to the machine or process by the operator. Unnecessarily tweaking the machine in order to make all parts stay on an X- bar line actually creates more variation, not less (usually done by a perfectionist operator). Over-correction means wild gyrations in machine adjustments performed by the operator. A P-chart is a control chart for 8HFCC MODULE 3-6

7 P-bar (P) attribute type data that shows plotted percentage of defective parts, assemblies, etc. for interpretation. Pareto Analysis Range (R) R-bar The P-bar is the average of all the calculated percentages P s in a set. A line indicating this average value is drawn on the control chart for ease of interpretation. Pareto Analysis is also known as the 80/20 rule (discussed in Module 1). Ask students if they remember meaning. Examples: 20% of a company s suppliers cause 80% of its incoming material problems; 20% of the components on your car cause 80% of your pain. Commonly known as a bar graph, problem prioritization tool, or vital few vs. trivial many. Displays data in descending order left to right typically. how your own sample/s or draw on flip chart. Range (R) is the difference between the lowest and highest values in a set of numbers, a measurement of spread (see igma also) whose goal is 0. Range limits for X /R chart (UCL & R-LCL) The R-bar is the average of calculated ranges. A line indicating it is drawn on the control chart for ease of interpretation. 8HFCC MODULE 3-7

8 table process igma (see also R-bar Chart ) Target Upper Control Limit (UCL) Upper pec(ification) Limit (UL) R-UCL and R-LCL control limits for the range portion of the X- bar/r chart. A stable process typically does not show data points beyond the control limits on a control chart. A stable process is considered predictable. igma is also known as standard deviation. Its symbol is a lazy 6 or a 6 tilted 45 degrees. A measurement of spread, it requires knowing R- bar first to calculate. The larger the R-bar, the larger the sigma or spread (not good). The target is the ideal goal, also called nominal. UCL or Upper Control Limit, a line labeled on a control chart that identifies the upper acceptable data threshold. Ideally you want both the LCL and UCL to be located within the specification limits (LL and UL). Upper pecification (pec) Limit, a number provided by the customer which indicates the upper most reading identified by the customer as acceptable. However, one should not believe that parts that are produced at the high or low end of the tolerance are equal in 8HFCC MODULE 3-8

9 Variable data performance to those close to the target. World Class Manufacturing (WCM) X-bar ( X ) X-double bar ( X ) Variable data derives from measurements taken by tools such as calipers, micrometers, CMM. Example: the diameter or depth of a hole, the length or weight of a part. World Class Manufacturing or simply World Class is sometimes referred to as Best-In-Class. The X-bar is the average (or mean) of a set of numbers. Compare to averages in sports, e.g., bowling, batting, etc. The term usually associated with R control charts. A line depicting the average is drawn on the control chart for ease of interpretation. The X-double bar is the average of a set of calculated averages. Activity 2 What is a process or a system? If you think about it, everything we do is a process and can be defined in a process flow chart. Examples: getting up in the morning is a process and going 8HFCC MODULE 3-9

10 Class Discussion: Can a process be a) stable and not capable, or b) capable but not stable? to bed is a process. Both examples involved actions (or operations ) and decisions. A system is a totality of actions in a definite organized method. I say you cannot have a system without a procedure. A system can t work otherwise. Write all answers on a flip chart for reference and end-of-class review (optional). Instructor: Display these 4 conditions : & C, N & NC, & NC, N & C in a quadrant clockwise from top left in order listed. Of the 4 scenarios presented by your instructor, write below which is the best-case scenario for a process? Compare your response with your neighbor s. Of the 4 scenarios presented by your instructor, write below which is the worstcase scenario for a process? Compare your response with your neighbor s. Activity 3 Create a Pareto Analysis based on the data and form provided. Calculate the total number of rejects /defects first and then the corresponding percentages. Follow the directions on handout. = stable N = not stable C= capable NC = not capable Answer: best-case is stable and capable. Answer: worst-case is not stable and not capable. Demonstrate with drawing of distorted bell curve beyond spec limits on flip chart. Remind students of Activity 1 8HFCC MODULE 3-10

11 where we discussed this tool. Draw (or show) an example to get them started. Activity 4 Advise students to lay out the bar graph with the #1 priority problem in the first column of the bar graph. The other category is always last and goes in the last place wherever that is. Allow ½ 1 hour for this activity. Create a Cause and Effect diagram. Label the 6 boxes with the 6 M s of Manufacturing. Follow the directions on the previous handout. Brainstorm with your neighbor and identify causes spread out among the 6 branches of your diagram. During the review portion of this activity, add causes identified by other teams to your diagram. Remind students of Module 1 where we discussed these 6 variables. Provide one or two examples to get them started. Advise students that in some cases one variable can go into two branches, e.g., poor training can go under Method or Manpower. Walk around to verify progress. Activity 5 Create a P-chart based on the data and form provided. Follow the directions on the handout, i.e., plot the data you calculated, label all lines Review the team results and have students read the most creative causes they came up with for the problem. Allow 45 minutes for this activity. 8HFCC MODULE 3-11

12 and then interpret the painting you made. Write your conclusions somewhere on the chart. Roleplay a supervisor on a production line and tell us what you would do / how you would react? Now discuss the results and your conclusions with your neighbor using terms you learned previously, e.g., out of control, large variation, etc. Activity 6 Create an X-bar chart based on the data and form provided. Follow the directions on handout, i.e., plot the data you calculated, label all lines and then interpret the painting you made. Write your conclusions somewhere on the chart. Role play a supervisor on a production line and tell us what you would do / how you would react? Judge stability, capability, amount of variation, etc. NOTE: Don t forget that you always look at Range chart to determine progress in reducing variation. Maybe there is none? Now discuss the results and your conclusions with your neighbor using terms you learned previously, e.g., out of control (or) in control, Verify comprehension of instructions before starting and walk around checking to see if any students are off-track. Allow hours for Activity 5. Continue the role of consultant, tracking progress as you walk around. Then review their conclusions with yours. Examples: Out of control on x shift Best shift is 2 nd shift Best day (least amount of P) is x day Worst day (greatest variation or amount of P) is x day. Verify comprehension of instructions before starting and walk around checking to see if any students are off-track. Allow hours for Activity 6. Continue role of consultant tracking progress as you walk around. Then review their conclusions with yours. Examples: 8HFCC MODULE 3-12

13 out-of-spec x times out of 25 days, stable and capable, etc. Think About It/Write About It: stable but not capable out of control best day (least amount of R) is x day worst day (greatest variation or amount of R) is x day ummary, findings, question journal entry: Answer the following in the next 15 minutes: 1. How do you see the Cause and Effect diagram and the Pareto Analysis tools helping a service company (hotel / restaurant)? 2. What company departments could use some or all of these tools of data summary and analysis? 1. Every month management could analyze the comment cards and identify the top 3 problems reported via a Pareto from a customer s point of view, and not their own view. It could help them in that it gives them a measurement tool, e.g. number of cards received without any problems. They could recalculate their service performance month to month. They could then set increasingly higher quality goals related to Continuous Improvement. 2. Engineering, Accounting, & H.R. Example: Companies could benefit from knowing the top 3 reasons given for not joining a company (H.R.), or the top 5 reasons for customer returns 8HFCC MODULE 3-13

14 3. What do you believe is the biggest reason so few service functions use these simple but very powerful tools? NOTE: service functions are service suppliers, e.g., maintenance. Key Terms (Engineering), or the tope 3 reasons for cost over run. 3. Typically people in service functions think these tools are for production environment. PC doesn t apply to us. Attribute data Brainstorming Capable process Cause and Effect diagram Control charts Cpk Out-of-control process P-bar Pareto Analysis Range R (R-bar) igma table process Target (Nominal) Variable data WCM X-bar X (X-double bar) 8HFCC MODULE 3-14