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Cards In This Set
| Front | Back |
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Components of each printing unit
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Plate, impression, and blanket cylinders
ink and water form rollers ductor roller |
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3 cylinder system
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Plate, blanket, impression. 1 color per each unit
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5 cylinder system
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2 separate plate and blanket cylinders share 1 common impression cylinder. 2 colors per unit.
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Bearer ring
cylinder body gutter undercut |
On edge of cylinders, where cylinders contact each other to alleviate strain on cylinder body
the part of the cylinder where the plate or blanket goes the sideways distance between bearer ring and cylinder body the vertical distance from the cylinder body to the top of the bearer ring |
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Calculate packing height of blanket cylinder
blanket thickness is .006 packing sheets are .003 each, 2 pieces used undercut is .009 |
Undercut - (blanket thickness + 2 pieces packing) = packing height of cylinder
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Total squeeze
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Packing height of blanket + packing height of plate
answer can be positive or negative! |
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Problems caused by inadequate packing and too much packing
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Inadequate packing = not enough pressure, therefore bad impression/no image
excessive packing = damages the blanket, causes slur & dot gain |
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Conventional and compressible blankets
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Conventional = hard roller, ink situates at the nip. is good for heavy ink coverage projects
compressible = better resolution, ink is distributed at the nip. it is lower pressure, so a good impression is more difficult to get than |
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Blanket surface and ink release
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If the blanket surface is smooth slurring might occur because it is harder to release the substrate if both are smooth, might slide before release and slur the image
if the blanket rougher, there is a much easier release, but it is harder to get a fine resolution due to the gritty, rough blanket. |
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Warp and weft
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Weft goes across cylinder, (weft to right)
warp goes around the cylinder (paper warp occurs from wrapping around cylinder) |
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Store blanket
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Flat, in container (not upright, causes gravity to be bad to it) in a cool, dark, dry place
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Stream feeder and single sheet feeder
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Stream feeder used for higher quality, larger, faster presses.
single sheet feeder used for smaller presses, usually limited in speed by the feeder. |
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3 point sheet alignment system on feeding board
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2 front stops and 1 side stop. side stop changes for work and turn but not for work and tumble. only 1 side stop used at a time.
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Work and turn vs work and tumble
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Work and turn - gripper stays the same
work and tumble - gripper changes |
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Spraying powder: pros and cons
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Pros: prevents offset and blocking
cons: soils press, makes blanket dirty (which prevents ink from sticking to it), makes it harder to print on back side of press sheet |
