Keywords: six sigma, DMAIC project, scrap, rework, analysis of variance, ANOVA, design of experiments, DOE, process audit sheets, India, foundries, foundry industry, SMEs, small and medium–sized enterprises, die casting

1. HIGH MATERIAL REJECTION
IN MALDEN M/C SHOP
Ambience of Six Sigma in
Indian foundries – an
empirical investigation
By
Dr. Bikram Jit Singh
Professor
MMDU Mullana

2. BUSINESS CASE
• BACKGROUND: PISTON MANUFACTURING FOR
EXPORT.
• MATERIAL REJECTION IN MALDEN M/C SHOP IS
15.5% Avg.FROM JAN.07 TO JUNE-07 (9.73 TO 33.92
%) RESULTING IN ADDITIONAL COST, LOSS OF
PRODUCTION AND CAN DELAY IN DELIVERY

3. OBJECTIVE
• TO REDUCE THE MATERIAL REJECTION IN FM-132
ALLOY FROM MAY-31.8 & JUNE-31.5 % TO 16.0%
• TARGET DATE IS DEC.-07
• ACHIEVED IN DEC.-07 - 12.0 %

4. SCOPE AND BOUNDRIES
• ALL PISTONS CAST FROM FM -132 ALLOY.
• BY IMPROVING THE PROCESS STARTING FROM
MELTING AND ENDING AT CASTING.

5. SCHEDULE
DEFINE PROBLEM 16.08.07
OBSERVATION 25.08.07
ANALYSIS 15.09.07
ACTION 16.09.07
CHECK 30.09.07
STANDARDIZATION 15.10.07
CONCLUSION 15.11.07

6. TEAM MEMBERS
N.S.BAWA CHAMPION
R.K SHARMA TEAM LEADER(QUALITY)
R.SOOD MEMBER(PRODUCTION)
Y.DHIR MEMBER(MELTING)
B.MATTU MEMBER (PRODUCTION)
H WALIA MEMBER (PRODUCTION)
M.HAYAT MEMBER (PRODUCTION )

7. RESOURCES REQUIRED
• THE PROJECT WILL BE HANDLED WITH EXISTING
FACILITIES & RESOURCES AVAILABLE.

8. REJECTION
10
33.92
12.52
11.42
9.73
15.18
20.63
15.2
12.81
11.75
8.5
8 6.7
0
5
10
15
20
25
30
35
%AGE
TAR.07 JAN07' FEB07' MAR07' APR07' MAY07' JUNE07' JLUY07' AUG07' SEP07' OCT07' NOV07' DEC07'
MONTH
FOUNDRY IN MACHINE SHOP (MALDEN)

9. RECENT SCRAP HISTORY FOUNDRY IN M/C
SHOP
8.1
6.9 6.6
7.2 7.1 7.2
0
1
2
3
4
5
6
7
8
9
%AGE
JAN08' FEB08' MAR08' APR08' MAY08' JUN08
MONTH

10. REJECTION
31.8
13.2
0.4
15.2
31.5
14
0.7
20.6
0
5
10
15
20
25
30
35
%AGE
May-07 Jun-07
MONTH
ALLOY WISE MATERIAL REJECTION IN MACHINE SHOP FOR MALDEN
FM132 HYPER FORGE TOTAL
ALLOYWISE REJECTION (MALDEN)

11. REJECTION PARETO
TOTAL
INSPECTED 8504 P= POROSITY 1=BOTTOM
GOOD 3896 S=INCLUSION/ SHRINKAGE2=RING ZONE
MATERIAL
SCRAP 2709 B= BLOW HOLE 3=SKIRT
SCRAP% 31.86% C=CRACK 4=PIN HOLE
DEFECTS P B' S DB
NOS. 1630 392 375 312
%AGE 60.2 74.6 88.5 100.0
19.2% 4.6% 4.4% 3.7%
PARETO CHART BY DEFECT TYPES IN MAY07 ALLOY FM132
1630
392
312
375
60.2
74.6
88.5
100.0
0
200
400
600
800
1000
1200
1400
1600
1800
P B' S DB
0.0
20.0
40.0
60.0
80.0
100.0
120.0
NOS.
%AGE
TOTAL
INSPECTED 39414 P= POROSITY 1=BOTTOM
GOOD 20233 S=INCLUSION/ SHRINKAGE2=RING ZONE
MATERIAL
SCRAP 12420 B= BLOW HOLE 3=SKIRT
SCRAP% 31.51% C=CRACK 4=PIN HOLE
DEFECTS P S B DB C
NOS. 5014 3714 2139 1263 290
%AGE 40.4 70.3 87.5 97.7 100.0
12.7% 9.4% 5.4% 3.2% 0.7%
PARETO CHART BY DEFECT TYPES IN JUNE07 ALLOY FM132
5014
3714
290
1263
2139
40.4
70.3
87.5
97.7
100.0
0
1000
2000
3000
4000
5000
6000
P S B DB C
0.0
20.0
40.0
60.0
80.0
100.0
120.0
NOS.
%AGE

12. PROCESS FLOW CHART
MELTING
R-R ALLOYING
COMPOSITION
CHECK
LAB
METAL
TREATMENT
APPROVAL
OF DENSITY
INDEX
CASTING
PREMELTING
CHIPS
INGOTING

13. PROCESS MAPPING
INPUT PROCESS OUTPUT
MANPOWER
MATERIAL
INDUCTION
FURNACE.
ALLOY COMPOSITION
FLUXES
MEASURING INST
METHOD
MELTING & FLUXING METAL FOR CASTING

14. CAUSE AND EFFECT DIAGRAM
GAS POROSITY
ON SKIRT AND
CROWN
METAL
OPERATORMETHOD
DIE
Tapping
Temperature
Casting
Temperature
Air venting
Flow lines
Crucible cleaning Good tool &
die paint
Pouring
APPLICATION
–FM132 ALLOY
Outer mould
relief
Hourly out put
Skimming of
metal
Rabbling with flux
Composition
VAC Test
For GAS Check
Water
Circulation
Degassing
Treatment

15. TRIALS
TRIALS CONDUCTED AT DIFERENT VAC TEST INDEX
PART N0.463
CASTING TEMP 690 -700 DEG C
VAC TEST
INDEX
PISTON
TURNED
GOOD MAT. SCRAP %AGE
0.6 29 23 6 20.6
0.5 35 31 4 11.4
0.4 28 25 3 10.7
0.3 34 31 3 8.8
0.2 30 27 3 10
0.1 36 34 3 8.3
0.0 30 28 3 10

16. TRIALS
TRIALS CONDUCTED AT DIFERENT CASTING TEMP.
PART NO. 463 ALLOY FM-132
DENSITY INDEX 0.3
CASTING
TEMP.DEG.
C
PISTONS
TURNED
VISUALY
GOOD
MAT.SC
RAP
POROSI
TY
MAT.
SCRAP
SHRINKA
GE
%AGE
735 100 26 62 12 74
720 48 21 15 2 35
710 40 32 7 1 20
700 40 37 3 - 7.5
690 36 33 3 - 8.3
680 43 37 3 3 13.9
670 40 37 3 - 7.5
BIGGER LOT
690-700 183 164 12 7 10.38

17. TRIALS
RESULTS OF A BATCH MADE FOR COMPARATIVE STUDY
PART NO. 381NP ALLOY FM -132
CELL NO. 5 HFC. NO. 9&10
DENSITY INDEX 0.2-0.3 CASTING TEMP. 690 -700 DEG. C.
PISTONS TURNEND 868
VISUALY GOOD 763
MAT.SCRAP 105
%AGE 12.09 ( 39.8 % for same Part no
made in May 07)

18. REJECTION
*
*INCLUDES PART NOS. 704, 31630/ 34807, 32639, 1080P AND 310NP MADE BEFORE JUNE07 AND ARE
HAVING 40% MATERIAL REJECTION. WITHOUT THESE IT IS 12%

19. RECENT REJECTION IN FM132 ALLOY
12.1
9.8
10.13
9.87
11.45
12.54
0
2
4
6
8
10
12
14
%AGE
JAN08' FEB08' MAR08' APR08' MAY08' JUN08
MONTH

20. CONCLUSION
MONTH GOOD MATERIAL
REJECTION
%AGE
MAY2007 3896 2709 31.8
JUNE2007 20233 12420 31.5
JULY2007 19456 7573 22.2
AUG2007 16910 6515 21.9
SEP2007 20866 7102 20.8
OCT2007 22114 4976 12.8
NOV2007 11492 3736 17.6
DEC2007 18176 3234 12.0
FM132 ALLOY REJECTION STATUS
•ONE MAN DEPUTED IN EACH SHIFT FOR CONTROLLING THE CASTING TEMPEERATURE
AND CHECKING THE DENSITY INDEX (VAC TEST ) AT REGULAR INTERVALS.
•CONTROL PLAN CHANGED ACCORDINGLY.