Voice of the Process
Panel Discussion
Lee Tait, Vice President Quality Assurance
Bell Helicopter Textron Inc.
Company Confidential
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
1
Summary
• Process capability analysis, when gathered on Critical and Key
Characteristics along with Key Process Variables can improve
design.
• Accomplishment of this effort can be achieved by linking
design requirements to current process maturity levels.
• The Cp/Cpk of a given process will depict whether it can hold
the required tolerances and if the process is performing to the
mean of the specified requirements.
• Driving improvement through process capability data yields
improves designs based on current capability of the
manufacturing environment, giving Engineering the insight
needed to provide achievable design parameters.
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
2
Agenda
• What is process capability?
• Using process capability to improve production
– Existing Designs
– New Designs
• Long-term design collaboration
• Benefits of understanding the Voice of the Process
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
3
Process Capability
The Strategy For Any Process Improvement
What Is Process Capability?
Process capability is the baseline measurement of how a
V-22 Pylon Support
process is performing.
Process Data
USL
0.378000
Target
*
LSL
0.375000
Mean
0.376133
Sample N
269
StDev (Within) 0.0002097
StDev (Overall) 0.0003468
I and MR Chart for Total hours by Process
Current
Individual Value
700
New
The500
“Y”400
300
600
Moving Range
300
200
100
0
Overall
Potential (Within) Capability
5.40
8.90
LCL=150.4Z.USL
Z.LSL
5.40
Cpk
1.80
1
1
0
400
Within
Mean=256.8
Z.Bench
100
500
USL
UCL=363.3
200
Subgroup
LSL
0
10
20
30
Time
Current
40
50
Cpm
60
*
Overall Capability
Z.Bench
3.27
Z.USL
5.38
Z.LSL
3.27
Ppk
1.09
New
1
0.3750
0.3755
0.3760
0.3765
The “Y”
Observed Performance
PPM < LSL
0.00
PPM > USL
0.00
PPM Total
0.00
0.3770
Exp. "Within" Performance
PPM < LSL
0.03
PPM > USL
0.00
PPM Total
0.03
0.3775
0.3780
Exp. "Overall" Performance
PPM < LSL
545.01
PPM > USL
0.04
PPM Total
545.04
Centering – Put The Process On Target
1
1
1
UCL=130.7
Spread – Reduce The Variation
R=40.01
LCL=0
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
4
Process Capability
Improvement Tool
• Engineering design requirements do not always match
Manufacturing process capability
• Existing Designs
– Use SPC to determine the Voice of the Process
– Communicate with Manufacturing and Engineering
– Changes yield improved first pass yield (FPY), decreased cost
and improved cycle time
• New Designs
– Collaboration among Engineering, Manufacturing, Quality and
Programs
– Engineering uses capability data during new product
development
– Produce product with higher FPY and lower cost
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
5
Process Capability
Collaboration
Engineering, Manufacturing,
Quality and Programs collaborate
on issues using data for problem
solving
Sustainment
Design
Quality
Development
Manufacturing
Field Data
Tooling
Process
Understanding
Planning
Results in improved quality and sustainable design
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
6
Voice of the Process
Benefits
• Improved yield
• Reduced cost
• Reduction in time and effort related to processing
defects
• Improved part flow and shipment
• Optimization of process capability
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
7
Process Capability
Process Improvement
Problem: Poor tool closures resulted in
numerous blade defects for voids and twist and
contour.
Result: A process change was made that
shifted the tool closures closer to the desired
thickness. After the process change, voids were
reduced by 90% and twist is moving closer to
the Engineering nominal.
Blade Tool Closures
Blade Twist
Boxplot of Tool Closure A
Upp Eng Tol
0.05
Low Eng Tol
Post Die Mean
Pre Die Mean
0.25
0.2
0.04
0.15
0.03
New Process
0.1
11
10
9
8
7
6
5
4
3
0
2
0.02
1
Deviation
0.05
-0.05
0.01
-0.1
-0.15
0.00
852 853 864 867 944 958 960 962 964 968 969 973 975 977 978 979 981 985 987
-0.2
-0.25
Current savings = $88K, projected savings = $500K in 2009
Copyright 2009 Bell Helicopter Textron Inc. All rights reserved
8