Concentric Screening
Commonly used Screening
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Amplitude Modulated screening
• Modulates the screen area by changing the size of halftone dots. To get
darker colors, the process uses larger dots — a larger amplitude
• This has been the typical method for creating halftones and process
screens for the last 100 years or more.
• Acceptable dot gain
• Smoothness
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Frequency Modulated screening
• Modulates the screen area by changing the number of randomly distributed
dots of the same size that appear in a given area.
• Can solve registration issues
• Has fine Detail
• Better press stability
• Good color saturation
• Ink Savings
• More stringent process control
• Grainy midtones and vignettes rather than a smooth gradation in tone.
• Buildup of ink or paper residue on the printing press blanket
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Registration Sensitivity
150 lpi - AM
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20µ Stochastic
Finer Detail
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Screen Visibility
The smoothest pattern is uniformly spaced
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Screen Visibility
smoothness
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Concentric Screening
Conventional Dot
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Concentric Dot
AM vs Concentric
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FM vs Concentric
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Rings Limit Ink Film Thickness
175 lpi “Normal” Dot
175 lpi Concentric Dot
Mass tone effect
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Mass tone effect
Color Saturation
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Screen Visibility
FM
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Concentric
175 lpi
Round
175 lpi
Concentric
175 lpi Round
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310 lpi Concentric
Press Stability
90,00%
80,00%
Percentage in print
70,00%
AM 25%
60,00%
Concentric 25%
50,00%
AM 50%
Concentric 50%
40,00%
AM 75%
30,00%
Concentric 75%
20,00%
10,00%
0,00%
vel1
vel2
vel3
vel4
vel5
Sheets
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vel6
vel7
vel8
vel9
Best of both worlds
• Greater color saturation
• Greater press stability
• Ink savings (10%-35%)
• Higher screen rulings
• More detail than AM
• Smoother than FM
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Real World Learnings
Plate imaging is more critical
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Printing is more stable
but … the color is different.
Technical Assesment : Plate Imaging
1. Use premium plate material
2. Optimize processing
3. Optimize laser focus
4. Optimize laser intensity
5. Optimize beam alignment
6. Calibrate your plate
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Technical Assesment : Plate Imaging
checkerboard
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Real World Learnings: Today’s Printer struggle
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12
10
10
8
8
6
6
Series1
Series2
Series3
Series4
4
4
2
2
0
1
2
3
4
5
0
6
1
Quality Materials
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3
4
5
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Ink Prices
12
12
10
10
8
8
Series1
Series2
6
Series3
6
Series4
4
4
2
2
0
1
2
3
4
Operational Cost
24
5
6
0
1
2
3
Printed Volume
4
5
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Benefits: Quality
● Quality is nr 1 pain, due to decreasing quality paper and ink. Daily fight to
keep the printing process under control.
● Customer quote: the best thing that I like about Concentric is the fact that
my customers don’t see anything related to screening, but notice an
improved quality.
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Benefits: Reduce ink consumption
● Cost reduction: ink prices increased 30% in 2008, ink represents up to
17% cost of printed job.
● Less ink means less wash intermediates: time + cost savings & waste
reduction
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Benefits: Reduce ink consumption
1 Manroland LithoMan 48 pag presses operating in 3-4 shifts, 50-60.0000
copies/hour
● Ink consumption:
500.000 kg
● Cost: @ 3 € per kg
1.500.000 €
● Savings 15%
220.000 €
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Benefits: Reduce wash intermediates
Why wash?
Blanket cylinder gets polluted by f.i. paper particles
Paper particles are picked from the paper by ink
Less ink = less particles
Less particles = reduction of wash intermediates
After every 50.000 copies or approximately 1 hour of printing there is a wash
intermediate that takes a few seconds... No big deal?
Washing cycle:
The machine reduces speed to 30.000 copies an hour
The press stops printing, the paper continues its travel trough the press into
the waste container...
The whole wash sequence takes 2 minutes
1.000 signatures are thrown away, no matter what size the press, every hour,
day in, day out
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Benefits: Reduce wash intermediates
Feedback from reference site :
Heatset Presses
●
2 x 64pp presses.
●
6 x 48pp presses.
●
1 x 16pp press.
Coldset Presses
●
2 x 64pp presses.
Quote: “We have decreased our wash intermediates, we print
60.000 copies instead of 50.000 copies”.
In practice: 4 wash intermediates less per day
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Benefits: Reduce wash intermediates
2 minutes at 30.000 signatures/hour = 1000 signatures
1 signature = 1.62 m2
1000 signatures = 1620 m2
Paper weight: 60 gr/m2
Paper waste in 2 minutes = 97.2 kg.....every hour!
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Benefits: Waste reduction
Without Concentric Screening:
24 wash intermediates x 97.2 kg = 2330 kg paper waste per day
With Concentric Screening:
20 wash intermediates x 97.2 kg = 1944 kg paper waste per day
2330 - 1944 = 356 kg per day
WASTE: yearly (200 x 356 kg) = 71.200 kg
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Benefits
● Quality
● Ink Savings
● Reduce wash intermediates > Waste reduction
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Think inside the dot.