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Case Problems
• Problem A– Parts Out of Specification– Solution: Poor Quality
• Problem B– Capacity Issue– Solution: Utilize Idle Machine 1 9
10
Today
Problem A - Quality
Problem Statement:Customer has recently found 121 Torsion Bars (T-Bar) with the Diameter out of specification. This issue is a recurring issue and is driving high scrap and sort costs.
Torsion
UCL – 0.2190 mmLCL – 0.2177 mm
Fishbone Diagram
T-bar Torsion
Section Is Too Close
To The UCL
Process
MeasurementPeople
Operator Bias
Gage R+R Too High
Shot Peen Increases Torsion Size
Gage Repeatability and Reproducibility Before Correction
Parts Operator A (mm) Operator B (mm) Range ǀA-Bǀ (mm)
1 0.21858 0.21861 0.000030
2 0.21862 0.21864 0.000020
3 0.21864 0.21865 0.000010
4 0.21866 0.21886 0.0002
5 0.21867 0.21883 0.00016
Sum of Range: 0.00042
Gage Error = Sum of Ranges Spec. Limit: 0.0012 (Note: Gage Error equals the sum of ranges only for 5 pc. Study)
Gage Capability = Gage Error / Spec. Limit 35.0%
Beyond 10% Approval
Gage Repeatability and Reproducibility After Correction
Parts Operator A Operator B Range ǀA-Bǀ
1 -0.012 -0.013 0.0001
2 -0.002 -0.003 0.0001
3 -0.011 -0.011 0
4 -0.009 -0.009 0
5 -0.003 -0.003 0
Sum of Range: 0.0002
Gage Error = Sum of Ranges Spec. Limit : 0.005
(Note: Gage Error equals the sum of ranges only for 5 pc. Study)
Gage Capability = Gage Error / Spec. Limit 4.0%
Under 10% Approval
Fishbone Diagram
T-bar Torsion
Section Is Too Close
To The UCL
Process
MeasurementPeople
Operator Bias
Gage R+R Was Too High
Shot Peen May Increase Torsion Size
T-Bar Process Analysis
Pack110
Q Q Q Q Q
Dept. 30 Dept. 53
Cut Length
Rough Grind
Wash Shot Peen
Paint Serrate Finish Grind
Wash10 40 50 60 70 80 90 100
Quality Check Station Inventory
Sample Analysis (59 T-Bars)Bottom Half
Gage Diameter (mm) Occurrences
0.21770 0
0.21775 0
0.21780 0
0.21785 0
0.21790 0
0.21795 0
0.21800 0
0.21805 0
0.21810 0
0.21815 0
0.21820 0
0.21825 0
0.21830 0
Top HalfGage Diameter (mm) Occurrences
0.21835 0
0.21840 0
0.21845 0
0.21850 1
0.21855 8
0.21860 18
0.21865 22
0.21870 5
0.21875 1
0.21880 2
0.21885 1
0.21890 1
n
xx
n
ii
1
Six Sigma Analysis
where
xi = observation of a quality characteristic (such as time)n = total number of observationsxbar = mean
ΣSix Sigma Analysis
where
xi = observation of a quality characteristic (such as time)n = total number of observationsxbar = mean
59
59i = 10.21863 mm
xi =
Six Sigma Analysis
0.21750
0.21760
0.21770
0.21780
0.21790
0.21800
0.21810
0.21820
0.21830
0.21840
0.21850
0.21860
0.21870
0.21880
0.21890
0.21900
0.21910
UCL 0.21890
xbar 0.21863
LCL 0.21757
T-Bar X Chart
T-Bar Samples
T-Ba
r Gag
e Di
amet
er (m
m)
Capable process, but shifted to the high end of the specification
Target (0.21830)
Six Sigma Analysis
0.21775
0.21780
0.21785
0.21790
0.21795
0.21800
0.21805
0.21810
0.21815
0.21820
0.21825
0.21830
0.21835
0.21840
0.21845
0.21850
0.21855
0.21860
0.21865
0.21870
0.21875
0.21880
0.21885
0.218900
5
10
15
20
25
Must Move This Way
)28613.0(x
Left Torsion Right Left Torsion RightMicro Micro Micro Micro Micro Micro
USL 7.645 USL 5.560 USL 7.645 USL 7.645 USL 5.560 USL 7.645LSL 7.595 LSL 5.530 LSL 7.595 LSL 7.595 LSL 5.530 LSL 7.595Tol. 0.050 Tol. 0.030 Tol. 0.050 Tol. 0.050 Tol. 0.030 Tol. 0.050 Part Left Torsion Right
7.605 5.545 7.604 7.629 5.56 7.6280.29952 (7.608) 0.21852 (5.550) 0.29968 (7.612) 0.29981 (7.615) 0.21873 (5.556) 0.29999 (7.620)
(0.003) (0.005) (0.008) 0.014 0.004 0.0087.604 5.543 7.603 7.627 5.558 7.625
0.29951 (7.608) 0.21847 (5.549) 0.29956 (7.609) 0.2998 (7.615) 0.21852 (5.550) 0.29963 (7.611)(0.004) (0.006) (0.006) 0.012 0.008 0.014
7.604 5.544 7.604 7.628 5.559 7.6260.29953 (7.608) 0.21849 (5.550) 0.2996 (7.610) 0.2999 (7.617) 0.21884 (5.559) 0.29994 (7.618)
(0.004) (0.006) (0.006) 0.011 0.000 0.0087.605 5.545 7.604 7.626 5.562 7.626
0.2996 (7.610) 0.21853 (5.551) 0.29966 (7.611) 0.29989 (7.617) 0.21863 (5.553) 0.29989 (7.617)(0.005) (0.006) (0.007) 0.009 0.009 0.009
7.605 5.545 7.605 7.629 5.56 7.6260.29957 (7.609) 0.21852 (5.550) 0.29965 (7.611) 0.29989 (7.617) 0.2188 (5.558) 0.29991 (7.618)
(0.004) (0.005) (0.006) 0.012 0.002 0.0087.605 5.543 7.604 7.63 5.559 7.628
0.29956 (7.609) 0.2185 (5.550) 0.29969 (7.612) 0.29992 (7.618) 0.218777 (5.557) 0.3 (7.620)(0.004) (0.007) (0.008) 0.012 0.002 0.008
7.605 5.546 7.605 7.629 5.561 7.6290.29957 (7.609) 0.21854 (5.551) 0.2996 (7.610) 0.29993 (7.618) 0.21877 (5.557) 0.30004 (7.621)
(0.004) (0.005) (0.005) 0.011 0.004 0.0087.603 5.543 7.605 7.63 5.561 7.627
0.29956 (7.609) 0.21857 (5.552) 0.29963 (7.611) 0.29978 (7.614) 0.21871 (5.555) 0.29994 (7.618)(0.006) (0.009) (0.006) 0.016 0.006 0.009
7.603 5.542 7.603 7.628 5.56 7.6290.2996 (7.610) 0.21853 (5.551) 0.29966 (7.611) 0.29986 (7.616) 0.21888 (5.560) 0.29997 (7.619)
(0.007) (0.009) (0.008) 0.012 0.000 0.0107.603 5.544 7.604 7.6247 5.562 7.626
0.29966 (7.611) 0.21854 (5.551) 0.29963 (7.611) 0.29989 (7.617) 0.21875 (5.556) 0.29984 (7.616)(0.008) (0.007) (0.007) 0.007 0.006 0.010
Average 0.02387 0.0162 0.0229Laser to Micro Max Deviation
0.009
Laser to Micro Max Deviation
0.0160.006
Laser to Micro Average Deviation
0.0217 0.018 0.022
Laser to Micro Average Deviation
0.008
0.027 0.018 0.022
0.025 0.018 0.026
0.025 0.016 0.024
0.024 0.015 0.024
0.022
0.021 0.017 0.022
0.024 0.015 0.021
10
Δ Dia. After Shot Blast
0.0240.0150.024
0.023 0.015
1
2
3
4
5
6
0.022
0.024 0.015
Spec
1
2
3
4
After Grind / Before Shot Blast After Shot Blast
Part Laser Laser LaserLaser LaserLaserPart
1
2
3
4
Spec
7
8
9
10
5
6
5
6
7
8
9
10
7
8
9
Process Study – Grind to Shot Peen
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Difference Between the Sizes
Diameter grew by an average of 0.016 mm after the shot peen
Problem A Conclusion
• Define– T-Bar diameter Too Close to UCL
• Measure– Gage R+R was Poorly Calibrated
• Analyze– Xbar Chart
• Improve– Decrease Rough Grind by 0.016 mm
• Control– Keep Gage R+R Under 10%
Problem B: Capacity Issue
Problem Statement: Part B orders were eliminated, and an increase in Part A orders occurred. The department will be operating inefficiency.
OP170Wash
IncomingFrom Heat
TreatOP130
OP140OD Grind
(12.3 sec/pc)
OP140OD Grind
(12.3 sec/pc)
OP160Ball Groove
Grind(84 sec/pc)
OP160Ball Groove
Grind(84 sec/pc)
IncomingFrom Heat
TreatOP130
IncomingFrom Heat
TreatOP130
IncomingFrom Heat
TreatOP130
Bottleneck
Capacity issueDocument Process
Dept.1
Dept.9
Dept.10
Today
Part A
Part A
Part B
Evaluating the Process• Cycle Time
• Productivity
• Parts Produced
84 sec/part x 80 parts per cycle 1 hour 52 minutesWheel/dress cycle + 04 minutes Total 1 hour 56 minutes
Parts/Hour 40.0Operational Activity (Hours) x 6.3
252 Parts/Shift/MachineMachines/Shift x 2Total Parts Produced 504 Parts/Shift
Productivity 90.0%Shift Time x 7.0 hoursOperational Activity 6.3 hours
Products Manufactured v. Product Demand
504
612
108
Products Produced
Product Demand
Short of Demand
Demand – Manufactured = Surplus/Deficient of Parts 612 – 504 = 108
17.6%
Recommendations
3) Don’t Change2) Buy A New Machine1) Reprogram Idle Machine
Dept.1
Dept.9
Dept.10
Today
Part A
Part A
Part B
Redesigning The Process
1) Manufacture at Full Capacity2) Produce According To Demand
Dept.1 Dept.
9
Dept.10
Proposal
Part APart A
Part A
Problem B Solution
Minimal Costs Associated
Use Idle Machineand
Produce According To Demand
Inexpensive Change Over Process
Reprogram Machine Replace Part B Pads With Part A Pads
Impact of Labor Costs Using Two Machines v. Three Machines
Labor Cost/Hour $16.00Hours/Shift x 7.00Labor Cost/Shift $112.00Shifts/Year x 365.00Labor Cost/Year $40,880.00
Deficit/Shift 108 PartsTime Needed for Each Part x 84 SecondsOver Time Needed to Complete Order 1.29 HoursEmployee Wage 16.00/HourOvertime Employee Wage x 2.00Labor Cost/Day $41.28Days/Year x 365.00Over Time Labor Cost/Year $15,067.20
Total Annual Cost $55,947.20
Case Problems
• Problem A– Parts Out of Specification– Solution: Poor Quality
• Problem B– Capacity Issue– Solution: Utilize Idle Machine
1 9
10
Today
Part A
Part A
Part B
Questions?