concentric screening

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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vel1 vel2 vel3 vel4 vel5 vel6 vel7 vel8 vel9

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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.