concentric screening
DESCRIPTION
Concentric Screening. Commonly used Screening. 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 - PowerPoint PPT PresentationTRANSCRIPT
Concentric Screening
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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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20µ Stochastic150 lpi - AM
Registration Sensitivity
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Finer Detail
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Screen Visibility
The smoothest pattern is uniformly spaced
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smoothness
Screen Visibility
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Conventional Dot Concentric Dot
Concentric Screening
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AM vs Concentric
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FM vs Concentric
175 lpi “Normal” Dot
175 lpi Concentric Dot
Rings Limit Ink Film Thickness
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Mass tone effect
Mass tone effect
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Color Saturation
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Screen Visibility
FM Concentric
175 lpi Round
175 lpi Concentric
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175 lpi Round 310 lpi Concentric
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Press Stability
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Sheets
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AM 25%
Concentric 25%
AM 50%
Concentric 50%
AM 75%
Concentric 75%
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• Greater color saturation
• Greater press stability
• Ink savings (10%-35%)
• Higher screen rulings
• More detail than AM
• Smoother than FM
Best of both worlds
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Real World Learnings
Plate imaging is more critical Printing is more stablebut … the color is different.
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1. Use premium plate material
2. Optimize processing
3. Optimize laser focus
4. Optimize laser intensity
5. Optimize beam alignment
6. Calibrate your plate
Technical Assesment : Plate Imaging
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checkerboard
Technical Assesment : Plate Imaging
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Real World Learnings: Today’s Printer struggle
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Quality Materials Ink Prices
Operational Cost Printed Volume
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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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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 €
Benefits: Reduce ink consumption
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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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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!
Benefits: Reduce wash intermediates
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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
Benefits: Waste reduction
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Benefits
● Quality
● Ink Savings
● Reduce wash intermediates > Waste reduction
Think inside the dot.