Upload
shashi-p-mishra
View
39
Download
0
Tags:
Embed Size (px)
Citation preview
D M A I CDefine Measure Analyze Improve Control
DDefine
MMeasure
AAnalyze
IImprove
CControl
Implementing Six Sigma Quality
at Better Body Manufacturing
2
D M A I CDefine Measure Analyze Improve Control
Dimension DPM
ASM_7Y 172475
ASM_8Y 85824
ASM_3Y 19786
ASM_9Y 3874
ASM_10Y 776
ASM_6Y 4
Overview
ABC Incorporated (ABC) is not achieving Six Sigma quality levels for all critical Body-Side Sub-Assembly dimensions as requested by their customers.
Ensure that all critical body-side subassembly dimensions are within Six Sigma quality levels of < 3.4 DPM. Cp ≥ 2.0 and Cpk ≥ 1.67.
• 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
• 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.
0
50000
100000
150000
200000
AS
M_7
Y
AS
M_8Y
AS
M_
3Y
AS
M_9Y
AS
M_1
0Y
AS
M_6Y
DPM
3
D M A I CDefine Measure Analyze Improve Control
Problem Statement & The Goal
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.
++
A-PillarReinforcement
B-PillarReinforcementBody Side Outer
++
A-PillarReinforcement
B-PillarReinforcementBody Side Outer
DDefine
4
D M A I CDefine Measure Analyze Improve Control
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
MMeasure
4776
172475
85824
19786
3874
0
50000
100000
150000
200000
ASM_7Y ASM_8Y ASM_3Y ASM_9Y ASM_10Y ASM_6Y
DPM
Assembly Dimensions with Highest Defects
5
D M A I CDefine Measure Analyze Improve Control
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 ≥ 2.0 and Cpk ≥ 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
Analyze Phase AAnalyze
6
D M A I CDefine Measure Analyze Improve Control
For our analysis we will do a DOE to check for levels that contribute to better quality product.
Weld Pattern (density)
Clamp Location
Operator
MachineMaterialsMethods
Clamp Weld Pressure
Press Tonnage
Die Cushion PressureMaterial
Thickness
Training
Yield Strength
Elastic Limit
Environment
Temperature
Humidity
QualityComponent Variability
Inspection Process Gage R&R
Body Assembly
Analyze Phase AAnalyze
Body Side Sub-AssemblyStamping Process
Outputs
Body Side Sub-Assemblies at
Six Sigma quality levels
Control Variables
Clamp Location Press TonnageWeld Density Die Pressure Clamp Pressure
Error States
Dimensional defects
Noise Variables
EnvironmentInherent Variation
Inputs
Material Thickness
Yield Strength
7
D M A I CDefine Measure Analyze Improve Control
Analysis of ASM_7Y and ASM_8Y
Analyze Phase AAnalyze
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
D M A I CDefine Measure Analyze Improve Control
Analyze Phase AAnalyze
Capability of B_7Y
698416 DPM0 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).
Capability of BS_7Y
9
D M A I CDefine Measure Analyze Improve Control
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.
Analyze Phase AAnalyze
10
D M A I CDefine Measure Analyze Improve Control
Analyze Phase AAnalyze
-1.0 -0.5 0.0 0.5 1.0
LSL USL
Capability Analysis of ASM_7Y at Tonnage > 935
USL
Target
LSL
Mean
Sample N
StDev (Within)
StDev (Overall)
Cp
CPU
CPL
Cpk
Cpm
Pp
PPU
PPL
Ppk
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
1.00
*
-1.00
0.09
12
0.163174
0.147855
2.04
1.86
2.23
1.86
*
2.25
2.05
2.46
2.05
0.00
0.00
0.00
0.00
0.01
0.01
0.00
0.00
0.00
Process Data
Potential (Within) Capability
Overall Capability Observed Performance Exp. "Within" Performance Exp. "Overall" Performance
Within
Overall
-1.0 -0.5 0.0 0.5 1.0
LSL USL
Capability Analysis of ASM_8Y at Tonnage > 935
USL
Target
LSL
Mean
Sample N
StDev (Within)
StDev (Overall)
Cp
CPU
CPL
Cpk
Cpm
Pp
PPU
PPL
Ppk
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
1.00000
*
-1.00000
-0.12833
12
0.101825
0.089161
3.27
3.69
2.85
2.85
*
3.74
4.22
3.26
3.26
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Process Data
Potential (Within) Capability
Overall Capability Observed Performance Exp. "Within" Performance Exp. "Overall" Performance
Within
Overall
-1.0 -0.5 0.0 0.5 1.0
LSL USL
Capability Analysis of ASM_9Y at Tonnage > 935
USL
Target
LSL
Mean
Sample N
StDev (Within)
StDev (Overall)
Cp
CPU
CPL
Cpk
Cpm
Pp
PPU
PPL
Ppk
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
1.00000
*
-1.00000
0.52083
12
0.206010
0.177098
1.62
0.78
2.46
0.78
*
1.88
0.90
2.86
0.90
0.00
0.00
0.00
0.00
10010.77
10010.77
0.00
3408.51
3408.51
Process Data
Potential (Within) Capability
Overall Capability Observed Performance Exp. "Within" Performance Exp. "Overall" Performance
Within
Overall
-1.0 -0.5 0.0 0.5 1.0
LSL USL
Capability Analysis of ASM_10Y at Tonnage > 935
USL
Target
LSL
Mean
Sample N
StDev (Within)
StDev (Overall)
Cp
CPU
CPL
Cpk
Cpm
Pp
PPU
PPL
Ppk
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
1.00
*
-1.00
0.39
12
0.215541
0.187663
1.55
0.94
2.15
0.94
*
1.78
1.08
2.47
1.08
0.00
0.00
0.00
0.00
2326.72
2326.72
0.00
576.00
576.00
Process Data
Potential (Within) Capability
Overall Capability Observed Performance Exp. "Within" Performance Exp. "Overall" Performance
Within
Overall
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.
Impact this has on ASM dimensions 7Y, 8Y, 9Y & 10Y on Tonnage
11
D M A I CDefine Measure Analyze Improve Control
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.
Analyze Phase AAnalyze
Input Variable Proposed ASM_9Y Setting Proposed ASM_10Y Setting
Clamp Location Location 2 Location 2
Weld Density (welds per X inches) 1.33 1.33
Clamp Pressure 2100 psi 2100 psi
12
D M A I CDefine Measure Analyze Improve Control
Analyze Phase AAnalyze
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
D M A I CDefine Measure Analyze Improve Control
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
Analyze Phase AAnalyze
14
D M A I CDefine Measure Analyze Improve Control
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.
-1.0 -0.5 0.0 0.5 1.0
LSL USL
Capability Analysis of ASM_3Y
USL
Target
LSL
Mean
Sample N
StDev (Within)
StDev (Overall)
Cp
CPU
CPL
Cpk
Cpm
Pp
PPU
PPL
Ppk
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
PPM < LSL
PPM > USL
PPM Total
1
*
-1
0
36
0.0851436
0.0971725
3.91
3.91
3.91
3.91
*
3.43
3.43
3.43
3.43
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Process Data
Potential (Within) Capability
Overall Capability Observed Performance Exp. "Within" Performance Exp. "Overall" Performance
Within
Overall
Die remachined to move mean +0.80
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
Analyze Phase AAnalyze
15
D M A I CDefine Measure Analyze Improve Control
Analyze Phase AAnalyze
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
D M A I CDefine Measure Analyze Improve Control
With the recommended changes the process performance will improve significantlyDimension Mean StDev
OverallDPM_Obsv DPM_Within DPM_Exp Pp Ppk Cp Cpk
ASM_1Y -0.035 0.165 0 0 0 2.01 1.94 2.47 2.39
ASM_2Y 0.259 0.152 0 0 1 2.20 1.63 2.31 1.71
ASM_3Y 0.000 0.097 0 0 0
ASM_4Y 0.009 0.115 0 0 0 2.90 2.87 3.53 3.50
ASM_5Y -0.330 0.145 0 0 2 2.30 1.54 3.72 2.50
ASM_6Y -0.284 0.160 0 1 4 2.08 1.49 2.24 1.60
ASM_7Y 0.090 0.148 0 0 0 2.25 2.05 2.04 1.86
ASM_8Y -0.128 0.089 0 0 0 3.74 3.26 3.27 2.85
ASM_9Y 0.521 0.180 0 0 0
ASM_10Y 0.395 0.191 0 0 0
AAnalyze
Analyze Phase
17
D M A I CDefine Measure Analyze Improve Control
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.
IImprove
Improve Phase
18
D M A I CDefine Measure Analyze Improve Control
Control Phase CControl
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
D M A I CDefine Measure Analyze Improve Control
Summary
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.
• 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.
• 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
Bring the key process output variables within Six Sigma quality level of < 3.4 DPM.
Cp ≥ 2.0 and Cpk ≥ 1.67