Unambiguous Conclusions of the Pamarco EFlo Extended Cell

Unambiguous Conclusions of
the Pamarco EFlo Extended
Cell Shape Performance
Tappi 2013 CorrExpo
By: Wilbert Streefland
Technology Coaching BvbA
©Technology Coaching 2013
Content
• The problem
• What is EFlo extended cell shape?
• How does EFlo compare to a
conventional (Hexagonal) screen roll
• The solution to the problem
©Technology Coaching 2013
The Problem
The problem
• Most high level printers suffer a 30% production time
loss due to colour not being right at start-up
• This is mostly due to not knowing at start-up how
much ink the screen roll will transfer
• Ink suppliers offer an ink kitchen and colour
matching software to compensate for this The
changing of the ink formulation on press is what
takes 30% of your production time!
• While using all your valuable production time for
changing the ink formulation you don’t compensate
for the dot gain changes due to the change in ink
film thickness Lowering ink transfer results in
printing smaller dots!
It is a must to have
consistent ink transfer at All Time!
©Technology Coaching 2013
What is EFlO
Comparing EFlo extended cell
and Hexagonal cell shape
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Measuring EFlo line count
• The length of the
horizontal line in the
image is: 0.01136 inch
• The number of cells
included: 5
• The calculation for LPI:
5/0.01136 = 440 LPI
• The vertical line has a
length of: 0.01363 inch
and includes 3 cells it
result in ≈ 220 LPI
©Technology Coaching 2013
What is EFlO
Comparing EFlo extended cell
and Hexagonal cell shape
Same number
of cells per area
Same line count
• Images top left and right
have the same number of
cells per area
• Images top left and
bottom left same line
count
©Technology Coaching 2013
Comparable Testing
Objective Pamarco
• The Objective is to compare EFlo
extended cell to conventional Hexagonal
cell shape in terms of:
– Ink transfer
– Colour consistency
– Smallest printed dot
– Bar width gain
– Moiré
– Cell cleanliness over time
©Technology Coaching 2013
Comparable Testing
Test Setup Comparing EFlo extended cell
versus Hexagonal cell shape
• 2 Screen Rolls with each 14 bands of which on both side
2 bands have identical specification for reference
• 3 substrates (Coated, Uncoated and Brown Kraft)
• 1 ink
• 2 production speeds (9,000 and 4,500 sheets/hour)
• Data collected for evaluation:
–
–
–
–
7,600 spectral readings
1,600 barcode scans
540 microscope images
84 image scans
©Technology Coaching 2013
Comparable Testing
Results comparable testing
•
•
•
•
•
EFlo normal line count transfers more ink than Hexagonal with the same
line count and same ink film thickness on the surface of the screen roll
EFlo with same cell volume as hexagonal (same number of cells per
area) transfers similar amount of ink
Higher speed results in lower ink transfer
Increasing screen roll line count and keeping IFT at same level results in
deeper cells This will lower ink transfer from cells More ink is left in
deeper cells which might result in faster clogging of cells
Reduction of ink transfer results in:
– Lighter colour: Can be adjusted by changing ink formula
– Lower dot gain: Adjusting means new print plates
EFlo allows using a higher line count specification while not
reducing ink transfer! (there are less cells/area on the
surface of the roll in that case)
©Technology Coaching 2013
Comparable Testing
L value versus IFT (Ink Film Thickness)
The L value of the Lab colour system can be used as a
measure for ink transfer
Coated paper
Uncoated paper
Cyan
Cyan
48
60
46
55
44
42
50
9,000 sht/h
eFlo std
eFlo std
40
hex
L
L
hex
38
eFlo high
eFlo high
45
36
o with
l
F
E
t
a
h
show t
s
k film
h
n
p
i
a
d
r
n
g
a
t
All
e coun
n
i
l
e
m
a
e of the
c
a
f
r
the s
u
s
on the
s
s
lower
e
a
n
k
e
c
v
a
thi
h
agonal
x
e
h
s
a
roll
if EFlo
e
l
L value
b
i
s
s
o
nly p
This is o ore ink!
m
transfers
34
40
32
30
35
0.0
2.0
4.0
6.0
8.0
IFT in µm
Cyan
60
10.0
0.0
12.0
2.0
4.0
6.0
8.0
10.0
12.0
IFT in µm
Cyan
48
46
55
44
42
4,500 sht/h
50
eFlo std
eFlo high
45
eFlo std
40
hex
L
L
hex
38
eFlo high
36
34
40
32
35
30
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.0
IFT in µm
2.0
4.0
6.0
IFT in µm
©Technology Coaching 2013
8.0
10.0
12.0
Comparable Testing
Dot size versus IFT
IFT 8µm (T03B, Coated)
size on
e
m
a
s
e the
v
a
h
mber
s
u
t
n
o
e
h
t
All d
te only
a
l
p
t
n
i
r
the p
rent.
e
f
f
i
d
s
i
igher
h
a
of dots
n
i
t
l
lt the
ts resu
u
o
s
d
e
r
s
s
a
e
L
dot as
r
e
p
e
r
u
press
shape!
t
u
n
o
d
a
dot gets n unexpected
sa
This wa
he tests
t
f
o
g
in
learn
©Technology Coaching 2013
Comparable Testing
Dot size versus IFT
Test T03B, IFT 8µm, coverage 15%
Dot size on plate 78 µm
EFlo standerd
355 LPI
Hexagonal
355 LPI
EFlo high
560 LPI
e and
iz
s
e
m
the sa
e
v
a
h
s
plate.
t
n
i
r
All dot
p
e
h
t on t
il ne coun andard show no
o st
The EFl
ape
donut sh
©Technology Coaching 2013
Comparable Testing
Benefits EFlo
• Higher ink transfer at same line count
specification compared to hexagonal cell
shape if the number of cells per area is
disregarded
• The need for cleaning and maintenance
still needs to be tested in more detail but
it is likely to be less for EFlo
©Technology Coaching 2013
The Solution
The Solution
• Use a proven cleanable screen roll configuration EFlo is the
alternative
• Use 3 screen roll specifications:
– Uncoated paper: IFT 6.5-7.7 BCM/inch², 254 LPI (EFlo 406 LPI)
– Coated paper: IFT 2.6-3.2 BCM/inch², <508 LPI (EFlo 812 LPI)
– Process colours on coated liner: IFT 1.9 BCM/inch², <812 LPI (EFlo
1295 LPI)
• Measure screen roll IFT before inking up the machine. Clean
screen rolls if screen roll IFT value is too low
• Regularly clean screen rolls
Changing screen rolls to 3 specifications will not result
in a need for new print plates!
The current common used high line count rolls
results in a larger variation on dot gain then using EFlo.
©Technology Coaching 2013
Thank you for your attention
More detailed information about EFlo
screen rolls and the test results can be
obtained at Pamarco, stand 111
©Technology Coaching 2013