3.2 - 3.3 - Blanket, Infeed, Splicing Flashcards
Bearers are
Hardened steel rings at end of plate & blanket cylinder
Most (not all) web offset presses have this
Blanket to blanket is aka…
The building block of the press
The plate gap on a web offset press is usually
0.25 - 0.5 inches
Plate bending involves 3 variables
Amount of force
Rate at which force applied
Radius angle of bends
Improper plate bending causes problems such as (3)
Misregister
Plate release when printing
Plate cracking
Plate lockup is commonly
Spring loaded
Reel-rod lockup
On web presses the plate gap is ________ than the blanket gap
Smaller
Blankets come in several forms
Premounted bars
Prepunched blankets
Blankets for gapless presses
Use press packing to control
Image length
Im feed systems include
Roll stand Spliced Metering rolls Dancer rolls Lateral positions (web) guides
Roll stand can hold ____ to _____ rolls of paper
1-4
Roll stand is usually _____ in configuration
Inline
Tension on web is required for quality printing T or F
True
Excessive tension caused
Web breaks
Tension is controlled _______
After roll stand and dancer roll and b4 first printing unit
Describe Metering rollers process
3 rollers grip web in two nips to provide break pressure
Purpose of Splicers
Join two web rolls
Allows non stop printing
What are the 2 types of splicers
Flying paster
Zero-speed splicer
A flying paster is
Splicer which makes a splice against an ex ping web while it’s moving
New roll is adhered using glue or double sided tape
Zero speed splicer makes splice against roll when it’s
Stopped moving
Press continuous to print at full speed during the zero speed splice to or f
True
What is a festoon
A vertical series of free spinning steel rollers ….stores 80-100 ft of paper for several seconds of press run during these eo speed splicing process
What three factors affect tension control
Tension
Length
Modulus of eleasticity - tendency of paper to stretch
Web guiding is
Side lay controls which control lateral position of web before printing or folding
Webs may be ______ guided or _______ guided
Centre
Edge
Web cutoff is usually made by a
Rotating knife cutoff cylinder
What are the 3 web break detectors
Mechanical (roller or finger)
Optical (infrared beam)
Pneumatic (air jet)
RPL (relative print length) occurs along the ________ of web and RPW occurs along the ________ of web
Length, width
