Pt9305 - Web Offset Technology

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PT9305 - WEB OFFSET TECHNOLOGY

UNIT 1: PRESS CLASSIFICATION & INFEED UNITS


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DEVELOPMENT

Alois Senefelder invented lithography in 1796

In 19th century, lithography was outclassed by letterpress for most

printing

About 1904, Ira Rubel invented offset.

The increasing need for high-speed printing led to the invention of

the web perfecting press in 1856.

1960s - rapid acceleration of web offsets growth


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MERITS AND DEMERITS OF WEB PRESSES

MERITS

Speed is high

Perfecting capability

Inline finishing

paper cost Range of substrates

DEMERITS

Complexity

Capital cost

Operating cost


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CLASSIFICATION - IN-LINE

IN-LINE

BLANKET TO BLANKET

COMMON IMPRESSION


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CLASSIFICATION - BLANKET TO BLANKET


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CLASSIFICATION - COMMON IMPRESSION


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ROLL STAND

THREE MAIN COMPONENTS IN A REEL STAND:

The reel support.

The sidelay.

The reel brake.

DIFFERENT TYPES OF REELSTAND

Single reelstand.

Double reelstands.

Revolving reelstands


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AUTOMATIC PASTERS - Flying speed paster


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AUTOMATIC PASTERS - Zero speed paster


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INFEED UNITS

Single drum infeed Rubber covered opendrum infeed

Open S-wrap infeed unit

Nipped single rollinfeed unit

Surface driven infeed unitNipped S-wrap

infeed unit


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DANCER ROLLER TYPES

TYPES OF DANCER ROLLERS

Vertical dancer roller.

Horizontal pivoting dancer roller.

Vertical pivoting dancer.

Horizontal dancer roller.


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WEB TENSION

Force applied to a continuous web of material in the machine

direction.


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TENSION CONTROL SYSTEMS

Closed loop control system

Open loop control system


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TENSION CONTROL SYSTEMS

Dancer roller tension control Load cell tension control


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ELECTRONIC TENSION CONTROL


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AUTOMATIC WEBBING UP DEVICE

Continuous belts running

between the reel splicer and

the folder running at the

edge of the paper web, with

loops into which front end ofthe web can be inserted in

such a way that paper web

can be directed through the

press.

The device is driven bythe servo motor and

disengaged once the

webbing up is completed


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FANOUT CONTROL AND WEB ALIGNER

Buzzle wheels Web aligner

1. The pivot guide

2. Actuator unit

3. Movable rollers

4. Main console

5. Sidelay Sensors

6. Fixed rollers


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WEB BREAK DETECTORS

Mechanical

Electronic

Pneumatic

Photoelectric sensor

Web catcher

Wrap up


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REEL HANDLING AND STORAGE


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QUESTIONS

1.Which among the following is business form printing

Inline

Blanket to blanket

Common impression

ANS: INLINE

2.Inventor of offset

Alois senefelder

Ira rubel

Gutenberg

ANS: Ira rubel


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QUESTIONS

3.Difference between lithography and offset

Ans: Image is first transferred to the intermediate carrier

4.Name any two manufacturers of web offset machines

Ans: MANROLANDHEIDELBERG


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THANK YOU

Pt9305 - Web Offset Technology

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