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W73 – Leaflet | Gravure Printing 360˚

W73 - Gravure Printing 360˚
AMSTERDAM - Multi-purpose printability tester
Version 2022-09

Introduction

Gravure printing is a widely used processing method often used to print large volumes of magazines and catalogues. The ink in gravure printing is transferred from an image carrier usually a steel cylinder that is electroplated with copper. A negative of the image is created on the gravure cylinder as a pattern of cells, which can be uniform or varying in depth. The image areas are created in recess, leaving the non-image areas in relief.
The cells of a gravure cylinder are filled with ink and subsequently transferred to the substrate under pressure.

The printing parameters as printing speed, printing force, number of pre-inking the printing form, the type of printing form (screen ruling, volume) and hardness/smoothness of impression cylinder can easily be changed. The adjustments are dependent to the combination of the type of ink and its viscosity, the type of substrate and the properties of ink and/or paper which will be tested.

Principle

The gravure attachment consists of an engraved printing form (disc), a doctoring system and an impression cylinder. A few drops of the ink are put on the printing disc, the surplus of ink is wiped off and two prints after each other are made on the substrate, which has been attached to the 360° impression cylinder. There is a wide range of different printing forms which can be used as well.

Gravure Printing 360˚, print

Method of operation

NOTE: This test has to be performed with a 360° sector without clamps!

Materials

Sector 360°, PU 90 Shore A
  • [402.153.412] Engraved printing disc *)
  • [435.031.412] Doctor blade holder
  • [180.431.710.001] Doctor blades
  • [364.000.174.090] Sector 360° without clamps, PU 90 Shore A

*) other types are available

 

  • 3 strips of substrate to be tested, dimensions 55 x 530 mm
  • gravure ink to be tested
  • disposable ink pipettes
  • lint free rags
  • velvet
  • cleaning solvent for ink
  • ethanol

 

Testing conditions

Standard test atmosphere according to ISO 187 (23,0 ± 1,0 °C and 50 ± 2% RH)

Sample conditioning

Be aware of the fact that a different way of conditioning of the samples can have influence on the results.

Standard settings

AMSTERDAM – multi-purpose printability tester

  • Printing speed: constant, 0,2 m/s
  • Printing force: 300 N
  • Pre inking gravure disc: 1

Preparation

 

  1. MOUNT THE 360° SECTOR WITHOUT CLAMPS, covered with PU 90 Shore A on the tester.
  2. Cut paper strips of 55 x 530 mm and mark with top and/or bottom side, machine and/or cross direction and a code for the paper.
  3. Select method Gravure 360°.
  4. Mount the doctor blade into the blade holder.
  5. Place the blade holder onto the two pins of the accessory holder.
  6. Clean the gravure disc with a cotton pad with ethanol.
  7. Place the gravure disc on the 1st shaft.
  8. Stir the bottle with ink well.
  9. Fill a disposable pipette with the ink.

Execution

  1. Touch the button [PRINT] to rotate the printing disc shaft into the start position.
  2. Mount a test strip on the sector by attaching the beginning and end of the test strip on the sector with a piece of tape.
  3. Press both side buttons to rotate the sector into the start position and to lower the doctor blade on the gravure disc.
  4. Apply a few drops of gravure ink on the printing disc just before the blade with the help of the disposable pipette.
  5. Press both side buttons to (pre) ink the gravure disc, to make the print and to come into the end position, then release the side buttons.
  6. Take the sample from the tester.
  7. For a next test with a very slow drying ink start with point 3, otherwise continue with point 9.
  8. Touch [BACK] to lift the doctor blade holder with blade.
  9. Clean the disc and the doctor blade.
  10. Assess the print result on the desired properties as described in Assessment.
  11. It is recommended to perform the test at least 3 times per sample.

Cleaning

  1. Clean the discs with lint-free rags and cleaning solvent and after that with ethanol.
  2. Clean the doctor blade.

Assessment

For smoothness

  1. Check the print visually or with an imaging analyser for every test strip.
  2. Calculate the average and if required the standard deviation.
  3. W41 might be a better test method to count the amount of missing dots.

For colour

Measure the colour with a spectrophotometer or compare visually with a (standard) sample.

NOTES

No dried ink may remain in the cells of the disc. In the case there is dried ink in the cells clean the disc with velvet saturated with the solvent of the ink.

Randstad 22 - 02

1316 BX Almere

The Netherlands

P.O.box 22022

1302 CA Almere

The Netherlands

+31 20 40 99 300 +31 20 40 99 339 info@igt.nl
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