Transcript THE SIX SIGMA APPROACH TO REDUCE THE PRODUCT …

THE SIX SIGMA APPROACH TO
REDUCE THE PRODUCT
DAMAGES IN THE
WAREHOUSE
Assist.Prof.Dr.Nihal ERGİNEL
Prof.Dr.Nimetullah BURNAK
2003
Introduction
The most common complaint of end customers
about the defects is the product damages.
This damage can occur to the warehouse in
which the products are packaged, stored, and
shipped.
Six sigma methodology is applied to eliminate
the complaints about the product damages.
Steps
 We set process map, and cause – effect diagram
to find the effective factors.
 Their priorities are assigned via Chi-Square test
and cause – effect matrix.
 It is decided that the product damages can occur
in any one of the two phases.
1. The first phase is the packaging for which packaging
materials and packaging method are considered.
2. The second phase is the transportation for which
handling equipments are analyzed.
 DOE is conducted separately for each of the
phases, and the results are discussed.
Process Map
Warehouse
forklift attachment
pressure
forklift attachment
pressure angel
Truck
Shopping Center
Truck
wet floor
dropped product
wet floor
nail
stroke in shopwindow
nail
traffic accident
traffic accident
hand vechile stroke
wood support stroke
type of board gutter
Critical parameter
sytrophor density
Process parameter
wet/dry board
Noise
sytrophor thickness
Instructions
distance between
board and product
number of product
trasported with forklift
Instructions
Customer
transporting without
package
stroke to the door,
elevator, banister, etc.
Cause and Effect Diagram
packaging
equipments
forklifts in the
warehouse
attachment
pressure
transported
witout
package
srofe to
the door
customer
stroke to
the
banister
stroke to
the
elevator
attachments
angel
distance
between
board and
product
packaging
method
truck
sytrophor
density
board
type
traffic
accident
nail in the
truck
wet board due
to the wet
floor of truck
sytrophor
tickness
damage on
the product
with/ without
wood
stroke in
support
shopwindow
number and the
wideness of the
ribbon
shopping center
dropped
product
wood support
stroke
hand
vechile
stroke
warehouse
number product
transported with
forklift
Chi-Square test
Table-1: Chi-Square Test: front; two sides; non-damage vs. model
Expected counts are printed below observed counts
Front
Two side
Non-damage
224
80
45451
A
106,90
61,97
45586,13
B
56
17
19273
45,20
26,20
19274,60
C
105
53
56058
131,34
76,13
56008,53
D
48
101
63867
149,56
86,70
63779,74
Total
433
251
184649
Chi-Sq =128,277 + 5,248 + 0,401 +
2,581 + 3,231 + 0,000 +
5,282 + 7,030 + 0,044 +
68,968 + 2,359 + 0,119 = 223,539
DF = 6, P-Value = 0,000
Total
45755
19346
56216
64016
185333
It is clear that Model A has
significantly higher number
of damages on front than
the other models. Model-D
has significantly lower
number of damages on
front
than
the
other
models.
This
main
difference between the
packaging types of model A
and D is the distance
between the product and
the board. The mentioned
distance is larger in modelD than in model-A.
Cause-Effect Matrix
Cause and Effect
Matrix
10
Rating of Importance to Customer
Process Inputs
1 Sytrophor density
2 Sytrophor thickness
3 Board gutter type
4 Distance between product and board
5 Forklift attachment pressure
6 Number product transported with forklift
7 Forklift attachment pressure angel
8 Door, elevator, banister etc. stroke
9 Hand vehicle stroke
10 Wood support stroke
11 Forklift stroke
12 Transport without package
13 Stroke in shopwindow
14 Package without wood support
15 Truck nail
16 Dropped product
17 Truck wet floor
19 Wet/dry board
20 Ribbon number and wideness
24 Truck traffic accident
Total
Damage on
the Product
1
9
9
8
8
7
7
6
6
6
6
6
5
5
5
5
5
4
3
2
1
113
2
Total
9
9
8
8
7
7
6
6
6
6
6
5
5
5
5
5
4
3
2
1
DOE-1on the packaging materials
and methods
Factors
Level (low)
Level (high)
Sytrophor density
SD1
SD2
Sytrophor thickness
ST1
ST2
The distance between
board and product
D1
D2
Type-1
Type-2
Board type
 The response is the area of the damage measured in
mm2 by using caliper. Gage R&R study was conducted
before DOE-1.
Anova Table for DOE-1
Analysis of Variance for mm2
Source
syt.dens
distance
board
distance*board
Error
Total
DF
1
1
1
1
11
15
SS
298,43
120,78
30,25
85,93
140,55
675,94
MS
F
P
298,43 23,36 0,001
120,78 9,45 0,011
30,25
2,37 0,152
85,93
6,73 0,025
12,78
The residual analysis is performed, and it was seen that residuals
were normal.
The plot of residuals versus time shows that there is no any
pattern.
Also, there is no indication of inequality of the variances by the
plot of residuals versus fitted values.
Main effects
Main Effects Plot - Data Means for mm2
syt.dens.
distance
25
mm2
23
21
19
17
-1
1
-1
1
Interaction effect
Interaction Plot - Data Means for mm2
distance
Mean
25
1
-1
20
15
-1
1
board
This interaction effect shows that response is robust for
board type-2.
Pie chart
Pie Chart of Source
distance*boa ( 86; 12,7%)
distance
Error
(121; 17,9%)
(141; 20,8%)
board
syt.dens
( 30; 4,5%)
•The sytrophor
density can
explain the 44%,
• the distance
between board
and the product
can explain 18%,
• the interaction
between distance
and board type
can explain 13%,
(298; 44,2%)
of the damaged
area.
DOE-2 on the set up values of forklift
which is transportation equipment
Factors
Level (low)
Level (high)
Attachment pressure
PR1
PR2
Attachment angel
AG1
AG2
The number of product
transported with forklift
TP1
TP2
Model-1
Model-2
The model of the product
The response is the severity of the damage.
The response :
Severity Defination
1
No damage
2
Little degree damage
3
Middle degree damage
4
Big degree damage
5
Very big damage
The attribute Gage R&R was made.
Anova for DOE-2
Analysis of Variance for response
Source
pressure
angel
Error
Total
DF
1
1
5
7
SS
3,1250
6,1250
2,6250
11,8750
MS
F
P
3,1250 5,95 0,059
6,1250 11,67 0,019
0,5250
 There is no any interaction. Attachment pressure and
angel are affected on the damage severity.
Main Effects
Main Effects Plot - Data Means for response
pressure
angel
3,1
response
2,7
2,3
1,9
1,5
-1
1
-1
1
Residual analysis
The residual analysis is performed, and it was seen that
residuals were normal.
The plot of residuals versus time shows that there is no any
pattern.
Also, there is no indication of inequality of the variances by the
plot of residuals versus fitted values.
Pie Chart
Pie Chart of Source
angel
Error
(3; 22,1%)
(6; 51,6%)
pressure (3; 26,3%)
The attachment
pressure and angel
are the significantly
main effects with 26%
and 52%, respectively
Results
By using the results from DOE-1 the packaging
method and the material used were redesigned.
The values of attachment pressure and the
attachment angel should be controlled
periodically according to DOE-2.
These improvements were implemented, and a
significant reduction was observed at the ratio
of damaged product.
Further Research
Since these researches just in warehouse,
it may be extended to other points of the
process map, and the ratio of damaged
product can be reduced.
Thank you.