The document discusses web offset printing. Web offset printing uses a continuous roll of paper fed through the printing press. There are two methods of drying - heat set uses forced air heating to dry ink rapidly, while cold set relies on natural evaporation and absorption to dry ink more slowly. The document focuses on web offset printing, describing characteristics like high printing speeds up to 900 meters per minute and applications including books, magazines, newspapers, and catalogs.

1. Welcome
To
Web offset Presses
MD ALI HOSSAIN
Jr. Instructor(Tech)
Graphic Arts Institute
Mail: mdalihossain.dte@gmail.com
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2. Web offset: Web offset is a form of
offset printing in which a continuous roll
of paper is fed through the printing
press.
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3. There are two methods of web offset
printing, regarding drying system, known as
heat set and cold set (or non-heat set). In
the heat set process, the ink is dried rapidly
by forced-air heating. In the non-heat set or
cold set process, the ink dries more slowly by
ordinary evaporation and absorption.
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4.  Perfecting Press – Prints on both sides of the
paper with one pass.
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5.  Web Fed Press: Printing press that prints from a
roll of paper
 Sheet Fed Press: Printing Press that prints from
cut sheets of paper
Web Fed
Sheet Fed
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6. Web offset printing
In the web offset printing, difference is made between
newspaper printing machines and commercial web
offset machines.
Characteristics of the web offset printing:
 High printing speed up to 900 m/min
 Grammages of 45 - 200 g/m² usual
 High runs
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7. Paper width: 11 and 56 inches (approximately
28 and 142 centimeters). Paper speeds: ranging from
5 to 50 feet per second (approximately 1.5 to 15
meters per second).
Applications:mass-market books, magazines,
newspapers, catalogs and brochures.
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8. Web offset printing
Drying oven
Hot air
Inlet temperature > 200°C
Web temperature approx. 120°C
The length of the oven is very important
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9. Web offset printing
Paper web in one unit
Plate cylinder
Blanket cylinder
Plate cylinder
Blanket cylinder
Paper web
Colour absorption
Water absorption
Moisture resistance pH5
No deformation
Resistant against cracking of
the colour
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10. Web offset printing
Center cut
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11. Web offset printing
Paper on the turner bars
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12. Web offset printing
Fold softening
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13. Web offset printing
Paper on the former fold
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14. Web offset printing
Stacker
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15. Web offset printing
Cylinder folder
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16. CPC Control Offset Press.
Fig : Heidelberg SM 74-5
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17. Ink Control System……..
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18. Dampening Control System……..
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19. Resistration Control System……..
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20. Thank You
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