Implementing Six Sigma Quality at Better Body Manufacturing

1. Implementing Six Sigma Quality at Better Body Manufacturing

2. PROBLEM STATEMENT ABC Incorporated (ABC) is not achieving Six Sigma quality levels for all critical Body-Side Sub-Assembly dimensions as requested by their customers. CURRENT PERFORMANCE TARGET PERFORMANCE Ensure that all critical body-side subassembly dimensions are within Six Sigma quality levels of < 3.4 DPM. Cp³ 2.0 and Cpk³ 1.67. ANALYSIS • Determined the correlation between body side and assembly dimensions. • Evaluated the significance of Tonnage > 935 for ASM_7Y & ASM_8Y. • Conducted a DOE for Clamp position for ASM_9Y & ASM_10Y. RECOMMENDATIONS • Change tonnage to > 935 to correct ASM_7Y and ASM_8Y • Set clamp position to location 2 for ASM_9Y and ASM_10Y • Re-machine A-pillar die to correct A_3Y and ASM_3Y Overview

3. D Define A A - - Pillar Pillar B B - - Pillar Pillar Body Side Outer Body Side Outer Reinforcement Reinforcement Reinforcement Reinforcement + + + + Problem Statement & The Goal PROBLEM STATEMENT ABC Incorporated’s customer wants ABC to apply Six Sigma problem solving methodology to insure that the body side subassembly is achieving Six Sigma quality levels of less than 3.4 defects per million for all critical body side subassembly dimensions. ABC needs an improvement strategy that minimizes the rework costs while achieving the desired quality objective. ABC’s goal is to produce module subassemblies that meet the customer requirements and not necessarily to insure that every individual stamped component within the assembly meets it original print specifications – sub-system optimizations vs. local optimization. GOAL

4. M Measure Assembly Dimensions with Highest Defects Measure Phase • Key Variables: • Assembly process variables: • Weld Pattern (density), Clamp Location, and Clamp Weld Pressure • Stamping process variables (body side): • Press Tonnage, Die Cushion Pressure, Material Thickness • Body Assembly Dimensions ASM_1Y through ASM_10Y KEY PROCESS INPUT VARIABLES KEY PROCESS OUTPUT VARIABLES

5. Analyze Phase A Analyze • Resolution alternatives (based upon past experience): • 1. Make adjustments to assembly process settings • 2. Reduce variation of components through better control of stamping • process input variables • 3. Rework stamping dies to shift component mean deviation that is off • target and causing assembly defects • Target Performance Level: • All ten critical assembly dimensions at Six Sigma quality level of £ 3.4 DPM. Cp³ 2.0 and Cpk³ 1.67 • Fish Bone and P-Diagrams: • Understanding potential causes of defects. From this we pick the assembly and component dimensions that require further analysis

6. Control Variables Clamp Location Press TonnageWeld Density Die Pressure Clamp Pressure Outputs Body Side Sub-Assemblies at Six Sigma quality levels Body Side Sub-Assembly Stamping Process Environment Inputs Material Thickness Yield Strength Quality Component Variability Temperature Operator Inspection Process Humidity Training Gage R&R Body Assembly Clamp Weld Pressure Yield Strength Die Cushion Pressure Weld Pattern (density) Material Thickness Error States Dimensional defects Noise Variables EnvironmentInherent Variation Elastic Limit Press Tonnage Clamp Location Machine Materials Methods Analyze Phase A Analyze FISHBONE DIAGRAM P-DIAGRAM For our analysis we will do a DOE to check for levels that contribute to better quality product.

7. Analyze Phase A Analyze Analysis of ASM_7Y and ASM_8Y Conclusion: BS_7Y and ASM_7Y are following a similar trend. A correlation chart to study this further shows high correlation. (Pearson correlation, R of 0.701).

8. Analyze Phase A Analyze Capability of B_7Y Capability of BS_7Y 0 DPM 698416 DPM Conclusion: B_7Y has 0 ppm compared to ~700K DPM in BS_7Y. Furthermore, BS_7Y shows strong correlation on dimension ASM_7Y. (Pearson correlation, R of 0.786).

9. Analyze Phase A Analyze XY Plot of Tonnage vs. BS_7Y Conclusion: Tonnage values above 935 greatly improves BS_7Y and brings it closer to the mean. Let’s see what impact this has on ASM dimensions 7Y, 8Y, 9Y, and 10Y by creating a subset of the data looking only at Tonnage > 935.

10. Analyze Phase A Analyze Impact this has on ASM dimensions 7Y, 8Y, 9Y & 10Y on Tonnage Conclusion: Setting Tonnage to greater than 935 resulted in ASM_7Y and ASM_8Y meeting the goal of <3.4 DPM. ASM_9Y and ASM_10Y require further analysis.

11. Analyze Phase A Analyze • DOE for Response Variable ASM_9Y • DOE factorial analysis shows Clamp Position is the only significant factor in determining ASM_9Y dimension • DOE Response Optimization for ASM_9Y • Set Clamp Position to Location 2 (level 1) • Optimizer recommends setting Weld Density to 1.33 weld per inch (level 1), but this appears to be a robust parameter, which could be changed for the benefit of process without reducing quality if processing time or cost shows a benefit. • Optimizer recommends setting Clamp Pressure to 2100 psi (level 1), but this appears to be a robust parameter, which could be changed for the benefit of process without reducing quality if processing time or cost shows a benefit. • Run additional tests at recommended settings to confirm results • Weld Density and Clamp Pressure are robust parameters and can be set to optimize the process capability to maximum level and lowest cost.

12. Analyze Phase A Analyze • DOE for Response Variable ASM_10Y • DOE factorial analysis shows Clamp Position is also the only significant factor in determining ASM_10Y dimension • DOE Response Optimization for ASM_10Y • Setting clamp to location 2 also improves ASM_10Y • Recommend same settings used to improve ASM_9Y to improve process capability which also allows for no changes to machine setup and helps reduce possible process concerns • Run additional tests at recommended settings to confirm results • Weld Density and Clamp Pressure are robust parameters and can be set to optimize the process capability to maximum level and lowest cost.

13. Analyze Phase A Analyze • DOE for Response Variable ASM_3Y • DOE factorial analysis shows that no factors are significant • Response Optimization shows no solution for response optimizer • Observe Process Capability of A_3Y and BS_3Y • ASM_3Y and A_3Y have a similar mean shift in the -Y direction • Correlation of Output Variables • No dimensional correlations appear to exist between ASM_3Y and A_3Y or BS_3Y • Stepwise Regression Analysis of BS_3Y • Tonnage and Die Pressure appear to be significant in determining dimension BS_3Y • Tonnage values < 920 may improve BS_3Y • Die Pressure appears to have no clear correlation to BS_3Y

14. Analyze Phase A Analyze • Process Capability of BS_ 3Y and ASM_3Y at Tonnage < 920 • Created subset of body data looking only at dimensions with Tonnage < 935 • Tonnage < 920 appears to improve the mean of BS_3Y slightly, but has no impact on improving the mean of ASM_3Y. • Capability of A_3Y and ASM_3Y with +0.80 mm mean offset • Manipulate data for A_3Y and ASM_3Y by +0.80 mm to simulate re-machining • Process capability shows 0 defects for A_3Y and ASM_3Y with this mean offset

15. Analyze Phase A Analyze • Conclusions • From the analysis of ASM_7Y and ASM_8Y we can conclude that: • Setting tonnage > 935 results in ASM_7Y and ASM_8Y meeting the goal • Analyzing ASM_9Y and ASM_10Y helps determine that: • Setting clamp position to location 2, weld density to 1 weld every 1.33” and clamp pressure to 2000 psi helps with dimensions ASM_9Y and ASM_10Y • Analyzing ASM_3Y helps us conclude that: • Re-machine A-Pillar die to move A_3Y to nominal – which could cause BS_3Y to shift towards nominal – effectively shifting ASM_3Y to nominal

16. Analyze Phase A Analyze With the recommended changes the process performance will improve significantly

17. I Improve Improve Phase • Recommendations for improving the process: • Set Tonnage to above 935 to improve ASM_7Y & ASM_8Y • Set Clamp to Location 2 to improve ASM_9Y & ASM_10Y • Re-machine the A-Pillar die to move the mean of A_3Y to nominal which in turn will move ASM_3Y to nominal • Implement the above recommendations and run additional samples to verify results.

18. C Control Control Phase • Recommended controls : • Implement a gauge on the body side component press to monitor tonnage • Implement an alarm and shut-off feature on the body side press if tonnage falls below 935 tons • Implement poke-yoke clamping fixture that ensures clamp is always in Position 2 • Establish an affordable control plan for ongoing monitoring of the 10 critical assembly dimensions.

19. PROBLEM STATEMENT ABC Incorporated is not achieving Six Sigma quality levels for all critical Body-Side Sub-Assembly dimensions as requested by their customers. BBM needs to apply Six Sigma problem solving methodology to establish an improvement strategy that minimizes rework costs, yet achieves the desired quality objective. ANALYSIS & RECOMMENDATIONS • Set Tonnage to above 935 to improve ASM_7Y & ASM_8Y • Set Clamp to Location 2 to improve ASM_9Y & ASM_10Y • Re-machine the A-Pillar die to move the mean of A_3Y to nominal TARGET PERFORMANCE Bring the key process output variables within Six Sigma quality level of < 3.4 DPM. Cp³ 2.0 and Cpk³ 1.67 RECOMMENDED CONTROLS • Implement a gauge on the body side component press to monitor tonnage • Implement an alarm & shut-off feature on body side press if tonnage falls below 935 • Implement poke-yoke clamping fixture that ensures clamp is always in Position 2 • Establish control plan for ongoing monitoring of the 10 critical assembly dimensions. Summary