Six sigma Problem solving bull gear carraro.ppt

Gear technology

1. Slide number: 1
6σ
Six Sigma Project
Project Number GNDP/14/07
Plant GNA Duraparts Pvt. Ltd.
Name of the Black Belt Sukesh Bhanot
Team Members DC Jain
Sukhwinder Singh
Preet Mohinder Singh
Poonam Salota
Date of Start 23.07.07

2. Slide number: 2
6σ
Phase – 1- Problem Definition
•Problem Statement
–Face Run Out Oversize after Heat Treatment
•Part number selected for study
– ETA-032
•Other similar part numbers having the problem
– JST-019,
•Process stages where the Problem is detected
–After Heat Treatment
–
–
•Current average rejection for last 6 months
– 6%
•Maximum and Minimum rejection in last 6 months
–Maximum rejection in a month -9%
–Minimum rejection in a month -3%

3. Slide number: 3
6σ
Phase – 1- Problem Definition
•Number of lines/presses/machines used for processing
– one
•Objective of the Project
– To Eliminate the Rejection
•Annual Savings in Rs. Lakhs if the defect is made zero and
horizontally deployed to other part numbers
– 1 Lac.
•Response
–Variable
•Specification (if the response is variable)
– 0.10 mm (max)
•Is R&R study required
–No
•If R&R study is required, % R&R to tolerance
– N.A

4. Slide number: 4
6σ
Phase – 1- Problem Definition
Process Mapping
START
RAW
MATERIAL
TEST
BLANK CUTTING
FORGING, FLASH TRIMMING, HOLE PIERCING
NORMALISING
SHOT BLASTING
ROUGH TURNING SIDE 1
ROUGH TURNING SIDE 2
ROUGH
TURNING
INSPECTION
FINAL TURNING SIDE 2
FINAL TURNING SIDE 1
TO SUPPLIER
REJECT/ REWORK
SCRAP
OK
NOT OK
OK
NOT OK
1. Rib Thickness
1. Distance of Rim Face
1. Face Run Out

5. Slide number: 5
6σ
Phase – 1- Problem Definition
Process Mapping
OK
Y
BLANK
INSPEC
TION
BROACHING 22 SPLINE
REJECT/ RW
SCRAP
DEBURING
BHT
INSPEC
TION
REJECT/RW
SCRAP
NOT
OK
NOT
OK
OK
HOBBING 70 TEETH
SHAVING 70 TEETH
X
1. Face Run Out

6. Slide number: 6
6σ
Phase – 1- Problem Definition
Process Mapping
OK
WASHING
WASHING
TEMPERING
SHOT BLASTING
BHT
INSPECTIO
N
X
REJECT/RW
SCRAP
NOT
OK
FINAL
INSPECTI
ON
REJECT/RW
SCRAP

PACKING
O
K
NOT
OK
HARDNES
S
TESTING
REJECT/RW
SCRAP
O
KNOT
OK
GAS CARBURISING
OIL QUENCHING

7. Slide number: 7
6σ
Phase – 1- Problem Definition
Phase
July Aug Sept
W1 W2 W3 W4 W1 W2 W3 W4 W1 W2 W3 W4
Define 
Measure &
Analyze
   
Improve  
Control  
Project Planning
Phases Planned Start
date
Planned
Completion
date
Actual start
date
Actual
completion date
Status
Define 23.07.07 23.07.07 23.07.07 23.07.07 Done
Measure &
Analyze
1.08.07 31.08.07 1.08.07 30.08.07 Done
Improve 1.09.07 15.09.07 1.09.07 14.09.07 Done
Control 16.09.07 30.09.07 15.09.07 28.09.07 Done

8. Slide number: 8
6σ
Phase – 1- Problem Definition
Photograph of defect part

9. Slide number: 9
6σ
Pareto (Based on last 6 months data)
22% of the rejection is due to Face R/O.
Defectw ise pareto analysis
208
98
72
58
18
6
67%
82%
95%
99% 100%
45%
0
100
200
300
400
500
ShavingFace R/OHobbing HT TurningDents
Defect
S
c
r
a
p

in

n
o
s
.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
C
o
n
t
r
ib
u
t
io
n

in

%
Phase – 1- Problem Definition

10. Slide number: 10
6σ
COPQ (Cost of Poor Quality) Calculation
Phase – 1- Problem Definition
Number of pieces rejected last month (for
the part number identified for study)
16
Number of pieces scrapped last month 2
Number of pieces reworked last month 14
Scrap cost/piece 1550
Rework cost/piece 20
Total scrap cost (Rs. Lakhs) for last month3100
Total rework cost (Rs. Lakhs) for last
month
280
Total Rejection cost (Rs. Lakhs) for last
month
3380
Extrapolated Total rejection cost (Rs.
Lakhs) for one year
0.41 LACS
Note: Rejection should include both rework and scrap

11. Slide number: 11
6σ
Phase – 1- Problem Definition
Suspected Sources of Variation for the Problem
statement (SSV’s)
1. Rib Thickness
2. Difference of Distance from Flange face to Rib
face
3. Face Run Out before Heat Treatment
4. Heat Treatment Process

12. Slide number: 12
6σ
Phase – 1- Problem Definition
SSV’s
1.Rib Thickness 
2. Difference of Distance from
Flange face to Rib face

3. Face Run Out before Heat
Treatment

4. Heat Treatment Process 
P
C
P
P
C
C
S
M
C
S
C
C
M
V
A
O
B
S
E
R
V
S
F
F
Legend: PC – Paired Comparison, PPC – Product/Process search, CS – Component Search, MCS – Modified Component Search, CC – Concentration chart
MVA – Multi-Vari analysis, OBSER – Observation, VS – Variable Search, FF – Full Factorial

13. Slide number: 13
6σ
Phase – 2- Measure and Analyze
Analysis # 1
• Objective: To eliminate the rejection due to Face R/O.
•Technique/Tool used:
- Paired Comparison, Product Process Search

14. Slide number: 14
6σ
Phase – 2- Measure and Analyze
S.No.Rib ThicknessResponse
1 19.68 G
2 19.70 B
3 19.70 B
4 19.70 G
5 19.72 G
6 19.72 B
7 19.74 G
8 19.75 B
9 19.75 B
10 19.75 B
11 19.78 G
12 19.80 B
13 19.80 G
14 19.82 G
15 19.82 B
16 19.86 G
Total count = 0
Conclusion:-
Max & Min Rib Thickness falls
under same (Good) Category.
Rib Thickness does not
contribute for
Face R/O
Count for SSV ( Rib Thickness)

15. Slide number: 15
6σ
Phase – 2- Measure and Analyze
S.No.DistanceResponse
1 0.6 B
2 0.8 G
3 0.8 G
4 0.8 B
5 0.9 G
6 1 G
7 1 B
8 1.2 G
9 1.2 B
10 1.3 G
11 1.4 B
12 1.6 B
13 1.8 G
14 2 G
15 2 B
16 2.4 B
Total count = 2.5
Conclusion:-
Total Count =2.5 <6
Difference of Distance
from Flange face to Rib
face does not contribute
for Face R/O
Count for SSV ( Distance)

16. Slide number: 16
6σ
Phase – 2- Measure and Analyze
S.No.Face R/OResponse
1 0.05 G
2 0.05 G
3 0.06 G
4 0.06 G
5 0.08 G
6 0.08 G
7 0.09 G
8 0.09 B
9 0.1 B
10 0.1 B
11 0.12 G
12 0.12 B
13 0.14 B
14 0.14 B
15 0.16 B
16 0.21 BTotal count = 11
Conclusion:-
Count is 11 i.e > 6.
Face R/O before HT
contribute for Face R/O
after HT.
Count for SSV (Face Run Out before Heat Treatment)
New Specification arrived from this
table is 0 – 0.08 mm

17. Slide number: 17
6σ
Phase – 2- Measure and Analyze
Analysis # 1
• Objective: To eliminate the face run out after HT.
•Conclusion(s): The face run out before HT is the cause for
the Face Run out after HT.
•Hence we drill down further.
-

18. Slide number: 18
6σ
Phase – 2- Measure and Analyze
Analysis # 2
Objective: To eliminate Face Run out before HT.
Suspected Sources of Variation for Face Run out before HT.
1.Face Run out before Broaching Process.
2.Broaching Process.
Technique/Tool used:
1. PPS
2. MVA

19. Slide number: 19
6σ
Phase – 2- Measure and Analyze
S.NO.FACE R/O RESPONSE S.NO.FACE R/O RESPONSE
1 0.02 G 51 0.025 G
2 0.03 G 52 0.02 G
3 0.02 G 53 0.015 G
4 0.03 B 54 0.025 G
5 0.02 B 55 0.015 B
6 0.025 G 56 0.025 G
7 0.03 G 57 0.02 G
8 0.05 G 58 0.04 G
9 0.05 G 59 0.02 G
10 0.035 G 60 0.03 B
11 0.02 G 61 0.02 G
12 0.02 G 62 0.03 G
13 0.025 B 63 0.02 G
14 0.05 G 64 0.025 G
15 0.02 G 65 0.03 G
16 0.02 G 66 0.05 G
17 0.045 G 67 0.05 G
18 0.02 B 68 0.035 G
19 0.045 G 69 0.02 G
20 0.02 G 70 0.02 G
21 0.035 G 71 0.025 G
Data Collection for 100 Pcs.

20. Slide number: 20
6σ
Phase – 2- Measure and Analyze
S.No.Face R/OResponse
1 0.015 G
2 0.015 G
3 0.015 G
4 0.015 G
5 0.015 G
6 0.015 G
7 0.015 G
8 0.015 G
9 0.015 B
10 0.015 B
11 0.02 B
12 0.02 B
13 0.02 B
14 0.02 B
15 0.02 B
16 0.02 B
Total count = 0
Conclusion:-
Min value contains both good
& Bad. Hence Count =0 < 6
Face R/O before Broaching
is not the reason for Face
R/o After Broaching.
Count for SSV (Face Run Out before Broaching

21. Slide number: 21
6σ
Phase – 2- Measure and Analyze
Analysis # 2
Face R/o before Broaching is not the reason for Face R/o
after broaching.
Now we apply MVA on Broaching process to drill down
further.

22. Slide number: 22
6σ
Phase – 2- Measure and Analyze
MULTI VARI ANALYSIS OF HOBBING PROCESS
T1
S1
 
 
 
 
 
 
 
 
 
 
 
 
T3
S1
0.15 0.16
0.05 0.15
0.07 0.05
AVG 0.09 AVG 0.12
RANGE 0.1 RANGE 0.11
T2
S1
T4
S1
0.12 0.04
0.07 0.08
0.08 0.06
AVG 0.09 AVG 0.06
RANGE 0.05 RANGE 0.04
Part to Part 0.11 
Part to Part Variation is Higher than Time to
Time Variation
 
Time to Time 0.07   

23. Slide number: 23
6σ
Phase – 2- Measure and Analyze
Conclusion :
Part To Part Variation =0.11
Time To Time Variation = 0.07
Since part to part variation is higher hence broaching
process is the reason for face Run out.

24. Slide number: 24
6σ
Phase – 2- Measure and Analyze
1. Flatness of resting plate.
2. Resting plate thickness (for strength).
3. Play between broach slide & main guide ways of
broaching machine.
4. Alignment of two broach holders.
5. Machine leveling.
6. Broach Holder.
SSV’s For Broaching Process:-

25. Slide number: 25
6σ
Phase – 2- Measure and Analyze
Verification of SSV’s
1.Flatness of resting plate checked & found ok.
2.Resting plate thickness for strength found ok.
3.Play between broach slide &main guide ways found ok.
4.Alignment of two broach holders checked with the help
of mandrel & found not ok.
5.Machine leveling ok with Spirit level.
6.The Broach holders were checked and lower broach
holder was found not ok.

26. Slide number: 26
6σ
Phase – 2- Measure and Analyze
 The misalignment of two broach holders were due
to worn out pins in the lower Broach holder. Hence
New broach holder was made with the help of
Maintenance department.
 Introduced the permissible Parameter of broach
holder in checklist for Preventive Maintenance.

27. Slide number: 27
6σ
Phase – 3 - Improve
Validation of the Root cause(s)- B Vs C
1Part number selected for
validation
ETA-032
2Better Condition With New Broach Holder
Current Condition With existing Broach Holder
3Sample size 6B,6C
4Sample type Pieces
5Response decided for
monitoring
Face Run Out
6Historic rejection 6%
7Lot quantity N.A
8Is alternating between B
and C condition possible
Yes

28. Slide number: 28
6σ
Phase – 3 - Improve
Validation of the Root cause(s)- B Vs C
Piece / Lot Better ( B ) Current ( C )
1 0.01 0.07
2 0.04 0.10
3 0.03 0.08
4 0.01 0.04
5 0.02 0.07
6 0.03 0.05
Count =11

29. Slide number: 29
6σ
Phase – 3- Improvement
Analysis - B Vs C
1Part number selected for validationETA-026
2Average of B .023
Average of C .068
3Over Lap / Total Count 11
4Xb – Xc (Amount of Improvement) .045
5Sigma (B) .011
6K (@ 95 % CL ) 2.96
7K * Sigma .032
8Xb – Xc >K*Sigma yes

30. Slide number: 30
6σ
Phase – 3 – Improve
Conclusions:
From the analysis, it is clear that the improvement has
taken place at 95% CL.

31. Slide number: 31
6σ
Phase – 3 – Improve
No Root cause(s) Actions Planned Planned
Completion
date
Responsibility Actual
completion
date
Status
1.
Worn Out
Pins in
lower
Broach
holder
New Broach
holder is made
15.09.07 Preet
Mohinder
Singh
14.09.07 Done

32. Slide number: 32
6σ
Steps in Variation analysis
Step 1 :
Identify the Parameter that requires Variation analysis
Parameter : face run out
Step 2 :
Identify are there multiple Product and Process streams
Number of streams : 1
Type of streams : 1
Phase – 4- Control

33. Slide number: 33
6σ
USL 0.08
Study dates
and Shift
17.09.07, A
Gage Bias
and
Uncertainity
(%)
10%
LSL
0
Any other
details
0.0075
0.016
Data Grouping and Sample details
Checking the consistency of part to part variation (Step 7)
Average Range (R-bar) (Round off to one decimal
more than the data)
Upper Control Limit (UCL) = D4*R-bar (Round off to
the same decimal as data)
Number of Groups (Number of time blocks x number
of streams)
Number of Samples in Each group (It is preferable
to collect 5 samples continuously from the process
so that the inherent variations are captured
25
5
Samples D3 D4
2 0 3.267
3 0 2.575
4 0 2.282
5 0 2.115
6 0 2.004
PHASE - 4 Control Phase

34. Slide number: 34
6σ
PHASE - 4 CONTROL PHASE
Step 3 :
Data Grouping and Sample details
Number of Groups 25
(Number of time blocks x number of streams)
Number of Samples 5
(in Each group)
(It is preferable to collect 5 samples continuously from the
process so that the inherent variations are captured)

35. Slide number: 35
6σ
Control Phase - Variation Analysis
Time BlockTime 1 2 3 4 5 Range Average
T-1 8.35AM 0.02 0.03 0.01 0.04 0.02 0.03 0.024
T-2 8.45AM 0.03 0.01 0.05 0.04 0.04 0.04 0.034
T-3 9.00AM 0.02 0.01 0.03 0.03 0.04 0.03 0.026
T-4 9.10AM 0.04 0.04 0.02 0.01 0.01 0.03 0.024
T-5 9.20AM, 0.02 0.02 0.01 0.01 0.01 0.01 0.014
T-6 9.30AM 0.02 0.03 0.01 0.04 0.02 0.03 0.024
T-7 9.40AM 0.03 0.01 0.05 0.04 0.04 0.04 0.034
T-8 9.50AM 0.02 0.01 0.03 0.03 0.04 0.03 0.026
T-9 10.00AM 0.02 0.03 0.01 0.04 0.02 0.03 0.024
T-1010.10AM 0.03 0.03 0.03 0.03 0.03 0 0.030
T-1110.20AM 0.03 0.03 0.05 0.04 0.04 0.02 0.038
T-1210.30AM 0.02 0.01 0.02 0.03 0.02 0.02 0.020
T-1310.40AM 0.02 0.02 0.01 0.02 0.02 0.01 0.018
T-1410.50AM 0.04 0.05 0.02 0.01 0.01 0.04 0.026
T-1511.00AM 0.02 0.02 0.02 0.01 0.01 0.01 0.016
T-1611.10AM 0.02 0.03 0.01 0.04 0.02 0.03 0.024
T-1711.30AM 0.03 0.01 0.05 0.04 0.04 0.04 0.034
Face Run Out after Broaching:
Data Collection for BULL GEAR
Step 4:

36. Slide number: 36
6σ
Phase - 4 Control Phase
Variation Analysis
Step 5:
Since no. of streams is 1, hence no need to do
mutli vary analysis.
Step 6:
Calculating part to part Variation
from the data in slide no. 36
Part to Part variation is 0.04

37. Slide number: 37
6σ
PHASE - 4 CONTROL PHASE
Checking the consistency of part to part variation
Average Range (R-bar) 0.025
(Round off to one decimal more than the data)
Upper Control Limit (UCL)=D4*R-bar 0.05
(Round off to the same decimal as data)
Lower Control Limit (LCL)=D3*R-bar 0
Is the Part to Part variation consistentYes
Step 8 :
Sample D3 D4
2 0 3.267
3 0 2.575
4 0 2.282
5 0 2.115
6 0 2.004

38. Slide number: 38
6σ
Step: 8 Check the consistency of the part to
Part variation
PHASE - 4 CONTROL PHASE
2520151050
0.06
0.05
0.04
0.03
0.02
0.01
0.00
Sample Number
S
a
m
p
le

R
a
n
g
e
R Chart for RESPONSE
R=0.0248
UCL=0.05244
LCL=0

39. Slide number: 39
6σ
Is the Range Chart plotted Yes
Are the Stratification levels more than 3 Yes
If the stratification level is <=3, then the Part to Part variation is
very less and the parameter does not require any monitoring. STOP.
Do not proceed further
Are there 7 consecutive points increasing, decreasing and one side of the
Mean range No
If yes write causes (if possible)
If the range contains patterns as described above, STOP. Plan for
DOE
PHASE - 4 CONTROL PHASE

40. Slide number: 40
6σ
Estimate PTP variation ( 6) by Using Rbar/d2 formula
Sigma = R-bar/d2
Sigma = 0.01
(Round off to one decimal more than data)
6 * Sigma = 6 * 0.01
= 0.06
(Round off to one decimal more than data)
Overall Average = 0.026
(Round off to one decimal more than data)
PHASE - 4 CONTROL PHASE
Step 9 :
Sample d2
2 1.128
3 1.693
4 2.059
5 2.326
6 2.534

41. Slide number: 41
6σ
PHASE - 4 CONTROL PHASE
Check the normality of data by using Histogram
Step 10 :
0.050.040.030.020.01
40
30
20
10
0
RESPONSE
F
r
e
q
u
e
n
c
y

42. Slide number: 42
6σ
Does the Overall Average lie in the group having maximum frequency or in the
adjacent groups Yes
Is there a gradual decreasing trend in frequency on both sides of the group
having the maximum frequency Yes
Are there two Modes (Two groups having maximum frequency) and both the
groups are distinctly separated No
Based on the above analysis, can you conclude that the histogram is Normal
Yes
Note: If the Histogram is non-normal, the estimated rejection which we
do in the next step may not be correct. Data transformation is required
to correct non-normality
PHASE - 4 CONTROL PHASE
Step 10 :

43. Slide number: 43
6σ
Rejection Analysis Using Sigma (Only for Normal distributions) (Step 11)
Average 0.026 Z(USL) = (USL - Average)/Sigma 5.4
Sigma 0.01 Z(LSL) = (LSL - Average)/Sigma -2.6
6*Sigma 0.06 Projected Rejection % above USL 0
(Based on the Normal table)
USL 0.08 Projected Rejection % below LSL 0.04
(Based on the Normal table)
LSL 0 Cpk = Zusl/3,Zlsl/3 1.8,0.86
Rejection Analysis if the results above show rejection on one side higher
than the other side
Target .04 Z(USL) = (USL - Target)/Sigma 4
Sigma 0.01 Z(LSL) = (LSL - Target)/Sigma -4
6*Sigma0.06 Projected Rejection % above USL 0.003
(Based on the Normal table)
USL 0.08 Projected Rejection % below LSL 0.003
(Based on the Normal table)
LSL 0 Cpk = Zusl/3,Zlsl/3 1.33, 1.33
PHASE - 4 CONTROL PHASE

44. Slide number: 44
6σ
Six Sigma Analysis (Step 13)
6Sigma = 75% of Tolerance
Actual part to part variation= 50% of tolerance.

Actions decided based on Six Sigma Analysis

Use pre control charts for monitoring
Remove 100% inspection if done on this parameter.
PHASE - 4 CONTROL PHASE

45. Slide number: 45
6σ
Phase – 4 – Control Phase
No Root cause Variation
analysis
done
Type of
control
method
decided
Status of
implementation
1Worn Out Pins
in lower Broach
holder
Yes Pre Control
Chart for
monitoring
Done.

46. Slide number: 46
6σ
DOE Tools selected for Process Improvement
Multi-Vari Analysis 
Paired Comparison 
Product process Search 
B Vs C Test 
Variation Analysis 
PHASE - 4 CONTROL PHASE

47. Slide number: 47
6σ
CONCLUSION:
We are using Pre Control charts for monitoring Face run out
after Broaching.
PHASE - 4 CONTROL PHASE

48. Slide number: 48
6σ
Thank you