Shell Weight reduction in BH521 6 Cavity
Duration Sept‐2007 to Nov‐2007Project Leader – Abdullah Ansari
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Project Start date : 01/09/07Target Completion date : 15/11/07 Date of proj presentation : 20/11/07Throughput Project Open days : 75Sponsors reviewed proj : YesNo of team meetings : 06
Savings : Current FY Rs. 2 L Annualized Rs. 6 L
Phase completed : D M A I CBelts % time on project : 40%Project review status : ( R / Y / G )
Sponsors MBB
Define Measure Analysis Improve Control
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DEFINE
Define project objective, expected benefits to the organization, team members, project schedule.
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Objective:
Benefits:
ProjectTeam:
Schedule: Measurement: 20/09/07 Analyze: 10/10/07 Improvement: 10/11/07 Control: 15/11/07
S J Chougule (Prod Engg)Ashok Khanna S S Kulkarni (Prod Engg)R K Choudhary Mahesh (Proc Engg)
S N Soddy (Quality)R K Jena (Melting)
A T Ansari
To increase number of BH521(6 Cavity) shells per MT of resin coated sand by reducing shell weight from 27 Kgs to 25 Kgs at molding while maintaining the minimum possible defectives due to shell making.
Savings: 52.5 K Rs per MonthImproved process cycle timeReduced operator fatigueEffective utilization of raw material
Revision 1
Shell Weight reduction in BH521 6 Cavity
MEASURE
Base Current Shell Weight – 26 to 27 Kgs CurrentCurrent Cycle Time – 257 Seconds per shell (14 shells per hour)Investment time – 85 Seconds
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6
50,000 ft Process Map
Inputs (Xs) Outputs (Ys)C/U/S
Resin Coated sand C No. of Shell per hourCycle Time C Shell weightHeated pattern U
C = Controllable
U = Uncontrollable
S = SOP
Shell Making
Shell Weight reduction in BH521 6 Cavity
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C & E Matrix
Rating of Importance to Customer
8 8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Process Step Process Inputs No.
of S
hell
per h
our
She
ll w
eigh
t
Total
1 Shell Making Investment time 6 6 962 Shell Making Resin coated sand 0 6 483 Shell Making Preheat time 2 2 324 Shell Making Preheat temp 0 2 165 Shell Making Baking time 2 0 16
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554943373125191371
28.5
28.0
27.5
27.0
26.5
26.0
25.5
Observation
Indi
vidu
al V
alue
_X=26.882
UCL=28.247
LCL=25.517
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I Chart of Shell Weight
‘I’ Chart for Shell Weight before improvement
ANALYZEWhich factor affecting on shell weight?
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10
Histogram of Shell Wt.
28.227.627.026.425.8
20
15
10
5
0
Shell Wt
Freq
uenc
y
Mean 26.88StDev 0.4979N 60
Histogram of Shell WtNormal
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Regression Analysis
180175170165160155
28.5
28.0
27.5
27.0
26.5
26.0
Pattern Temp
Shel
l Wei
ght
S 0.494345R-Sq 3.1%R-Sq(adj) 1.4%
Fitted Line PlotShell Weight = 24.35 + 0.01501 Pattern Temp
Pattern temperature is not the major factor resulting in increase or decrease of shell weight.Take trials by varying temperature and investment time and redo regression analysis.
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Regression analysis – Fitted line plot for Inv time
8580757065
27.5
27.0
26.5
26.0
25.5
25.0
Investment time
Shel
l wei
ght
S 0.195085R-Sq 96.5%R-Sq(adj) 95.6%
Fitted Line PlotShell weight = 18.58 + 0.1025 Investment time
IMPROVE
To decide optimum process parameters to achieve required shell weight.
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DOE
RUN Pattern Temp x Investment T ime Plan / Status Actual Avg TempActual Avg Shell
Weight
Run 1 220 x 65 04.10.2007 220.8 25.14
Run 2 220 x 75 04.10.2007 220.9 26.21
Run 3 220 x 85 04.10.2007 220.9 27.08
Run 4 240 x 65 07.10.2007 240.8 25.04
Run 5 240 x 75 07.10.2007 240.2 26.13
Run 6 240 x 85 07.10.2007 238.8 26.63
Run 7 260 x 65 08.10.2007 260.1 25.36
Run 8 260 x 75 08.10.2007 262.6 27.09
Run 9 260 x 85 08.10.2007 261.4 28.04
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AB
B
A
20151050
Term
Standardized Effect
1.99
A Inv estment timeB Pattern Temprature
Factor Name
Pareto Chart of the Standardized Effects(response is Shell weight, Alpha = .05)
DOE Results
Investment time
Patt
ern
Tem
prat
ure
8580757065
260
250
240
230
220
210
> – – – – – – < 25.0
25.0 25.525.5 26.026.0 26.526.5 27.027.0 27.527.5 28.0
28.0
Shell weight
Contour Plot of Shell weight vs Pattern Temprature, Investment time
Investment time = 69.9450Pattern Temprature = 220.231Shell weight = 25.5168
Investment time = 65.0255Pattern Temprature = 240.176Shell weight = 25.2558
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Optimized Process controls for further full heat trials
• Investment time = 65 to 70 Seconds– Target 67/68 Seconds
• Pattern Temperature = 230 to 250 0C– Target 240 0C
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Results of full heat trials with new process parameters
332925211713951
26.4
26.2
26.0
25.8
25.6
25.4
25.2
25.0
Observation
Indi
vidu
al V
alue
_X=25.651
UCL=26.362
LCL=24.940
I Chart of Shell Wt
26.025.625.224.824.424.023.6
30
25
20
15
10
5
0
Shell WtFr
eque
ncy
Mean 25.00StDev 0.5079N 172
Histogram of Shell WtNormal
Data of 1stTrial
Data of shell weight 172 shells ~ 5 heats
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Any effect on Casting Rejection…?
• Before• Casting rejection 6%• Casting rejection due to swelling and shell crack – 1.5%
• After• Casting rejection in full heat trials 5%
• Casting rejection due to swelling and shell crack – 1%
No Negative Effect
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Improvement Summary
• Earlier shell weight 26.9Kgs (based on data collected on 18/09/2007), Now 25.5Kgs
• Saving of 1.4 Kg resin coated sand per shell• Earlier investment time 85/90 Seconds, Now 67 Seconds• Cycle time reduction by 18/23 Seconds per shell.• Forecasted saving
– Due to saving in resin coated sand• Rs 49000 per month• Rs 5.88 Lacs per annum
– Productivity improvement• 20 seconds x 14(shells per hour) = 280 Seconds ~ 1 shell per hour• Capacity enhancement of 3744nos of castings per month
CONTROLIntroduce Controls to sustain the improvement
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Control Plan
• Resin coated sand– Sand properties should be strictly within specifications at receiving
inspection.– Build up should be 49% to 52%
• Investment time– Should be 65 to 70 Seconds. 67 is ideal. To be ensured while setup
approval.• Pattern Temperature
– Target for 2400C – Measure by infrared gun while setup approval– Maintain temperature by keeping burners on/off for every 2 alternate
shells, as temperature on machine can not be controlled automatically.
Thank You