1. Implementing Six Sigma Quality
at Better Body Manufacturing

2. PROBLEM STATEMENT CURRENT PERFORMANCE TARGET PERFORMANCE ANALYSIS
Overview
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. Cp ³ 2.0 and Cpk ³ 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

3. Problem Statement & The GoalD
Define
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 + A -
Pillar
Reinforcement B
Body Side Outer

4. KEY PROCESS INPUT VARIABLES
Measure Phase M
Measure
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
Assembly Dimensions with Highest Defects

5. Analyze Phase A 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. Cp ³ 2.0 and Cpk ³ 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. Body Side Sub-Assembly
Analyze Phase A
Analyze
FISHBONE DIAGRAM
Weld Pattern (density)
Clamp Location
Operator
Machine
Materials
Methods
Clamp Weld Pressure
Press Tonnage
Die Cushion Pressure
Material Thickness
Training
Yield Strength
Elastic Limit
Environment
Temperature
Humidity
Quality
Component Variability
Inspection Process
Gage R&R
Body Assembly
P-DIAGRAM
For our analysis we will do a DOE to check for levels that contribute to better quality product.
Body Side Sub-Assembly
Stamping Process
Outputs
Body Side Sub-Assemblies at
Six Sigma quality levels
Control Variables
Clamp Location Press Tonnage Weld Density Die Pressure Clamp Pressure
Error States
Dimensional defects
Noise Variables
Environment Inherent Variation
Inputs
Material Thickness
Yield Strength

7. Analyze Phase A 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 Capability of B_7Y Capability of BS_7Y 0 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 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 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 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 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 mm mean offset
Manipulate data for A_3Y and ASM_3Y by mm to simulate re-machining
Process capability shows 0 defects for A_3Y and ASM_3Y with this mean offset

15. Analyze Phase A 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. Improve Phase I 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. Control Phase C 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 critical assembly dimensions.

19. ANALYSIS & RECOMMENDATIONS
Summary
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.
TARGET PERFORMANCE
Bring the key process output variables within Six Sigma quality level of < 3.4 DPM. Cp ³ 2.0 and Cpk ³ 1.67
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
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.