Lithograffi Offset

Offset Lithography

Disgrifiad

Lithograffi Offset yw un o'r dulliau argraffu (yn ystod argraffu) mwyaf cyffredin.

Prosesau

Mae'r broses argraffu lithograff yn gweithio drwy drosglwyddo (offset) delwedd inc o blât i flanced rwber i'r arwyneb printiedig (papur neu gerdyn), sef Planograffig. Mae Lithograffi Offset yn dibynnu ar yr egwyddor nad yw olew a dŵr yn cymysgu. Dyma'r broses:

  1. Mae platiau lithograffi yn cael eu cynhyrchu, llenni alwminiwm yw'r rhain (angen 4 llen i argraffu mewn lliw llawn CMYK [gwyrddlas, magenta, melyn, du] fel bod y ddelwedd sydd i'w hargraffu yn sefyll allan ychydig.
  2. Mae'r plât yn cael ei dampio drwy'r adeg ond dim ond y rhan lle mae'r ddelwedd sy'n denu'r inc olew.
  3. Wrth i'r silindr argraffu gylchdroi, mae'n trosglwyddo'r inc i'r silindr blanced.
  4. Mae'r silindr blanced yn cylchdroi i wasgu'r inc ar y papur/cerdyn, tra bydd hefyd yn tynnu'r papur drwy'r wasg gyda chymorth y silindr gwasgu.
  5. Ailadroddir y broses hon i osod y 3 inc arall i gwblhau'r broses argraffu lliw llawn.


Manteision

  • Argraffu ar lawer o wahanol fathau o bapur.
  • Safon uchel a glân i'r delweddau.
  • Unwaith y mae wedi'i osod, mae'n broses gyflym iawn.
  • Gall platiau argraffu miloedd o brintiau
  • Cost effeithiol, platiau rhad
  • Hawdd i'w osod

Anfanteision

  • Gall y lliwiau amrywio ychydig.
  • Gall y papur ymestyn.
  • Cymryd amser i weithgynhyrchu platiau
  • Gwasg Lithograffi Offset gychwynnol yn gostus iawn
  • Rhaid edrych ar y marciau argraffu i sicrhau argraffiad cyson.

Description

Offset Lithography is one of the most common on-press (printing methods) processes.

Processes

The process of lithograph printing works by transferring (offset) and inked image from a plate to a rubber blanket to the printed surface (paper or card) known as Planographic. Offset Lithography relies on the principle that oil and water don't mix. The process follows

  1. Lithography plated are manufactured, these are aluminium sheets (4 sheets required for full colour printing CMYK) are produced so the image to be printed stands out slightly.
  2. The plate is constantly dampened but only the image area will attract the oil based ink.
  3. The printing cylinder rotates it transfers the ink onto the blanket cylinder.
  4. The blanket cylinder rotated to press the ink onto the paper/card, whilst also pulling the paper through the press with aid of the impression cylinder.
  5. This process would be repeated to lay the other 3 inks to complete the full colour printing.


Advantages

  • Print on many types of different papers
  • High image quality, clean images.
  • Once set put is a very fast process.
  • Plates can print thousands of prints
  • Cost effective, cheap plates
  • Quick to setup

Disadvantages

  • Some colour variation can happen
  • Paper can stretch
  • Time consuming to manufacture plates
  • Initial Offset-Lithography press very costly
  • To ensure a consistent print the printer marks must be checked.

Adnoddau Resources

Lithograffi
Lithography
Lithograffi Offset
Offset Lithography