IGT W46 Information Leaflet
Also see for AIC2-5T2000: Quick start guide
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IGT Testing Systems, P.O.Box 12688, 1100 AR Amsterdam, The NetherlandsKeienbergweg 25, 1101 EX Amsterdam, The NetherlandsPhone +31 (0)20 409 9300, Fax +31 (0)20 697 4842, E-mail: info@igt.nl Internet: www.igt.nlIGT Information leaflet W46IGT AIC2-5T2000WET ON WET PRINTING (85 Shore A)Version : October 2003Introduction:When inks are used on a two-colour offset printing press thesecond ink film is printed over the first ink film while it is stillcompletely wet. For multi colour presses the same can be said forthe other colours. In order to do so the inks have to be trapped ontack and/or viscosity. The systems for measuring tack and/orviscosity measure these ones as it is in the tin, without theinfluence of absorption by the paper.On the printing press, as soon as the ink is printed on the paperthe low viscosity components of the ink will penetrate into thepaper and the viscosity and tack of the ink will increase rapidly.The longer the ink is on the paper, the bigger this increase ofviscosity and tack will be. The time interval between individualprints differs considerably in various types of presses. In practicethese interval times are between about 0.03 and 3 s. For properadjustment of ink for wet-on-wet printing a printability tester isessential, operating from very short time intervals upwards.Although in practice water is used and an emulsion is formed,this method gives very good results for testing wet-on-wetprinting.There are 2 methods:W46 for a printing form with coated rubber of 85 Shore A forsmooth papers (described in this leaflet)W69 for a printing form with coated rubber of 65 Shore A forsmooth and rather rough papersPrinciple:A set of two colours of offset inks is printed on each other onpaper in both the colour sequences and with different intervaltimes. The results are observed visually or with the help of adensitometer. The best print quality and the best ink transfershow the right colour sequence.Also for a four colour series of offset inks the inks always mustbe tested in sets of two colours.Method of operation:• It is recommended to execute the test in the standardatmosphere; to most standards it is 23.0 ± 1.0 °C (73.4 ± 1.8 °F)and 50 ± 2% rh.• For the operation of the AIC2-5T2000, the High Speed InkingUnit 4 and the ink pipette follow the instructions of the manuals,IGT information leaflet W100 and the displays accurately.• Handle the samples carefully.Preparation1. Condition the papers, inks and equipment during >6 hours inthe standard atmosphere.2. If necessary cut the paper strips (preferable 55 x 320 mm, 4- 6 strips per set of inks) and mark them with top and/orbottom side, machine and/or cross direction and a code forthe type of paper.3. Adjust the printing force of the printing disc shafts to 1000N and pay attention for the right backlash. See W100.4. Adjust the speed to constant (5), 1.0 m/s.5. Check and if needed, move the slide in front of the sectorinto the constant speed mode (5).6. Check the functioning of the AIC2-5T2000 following theinstructions in the chapter “Execution”.7. Fill the ink pipettes with the inks to be tested.8. Adjust the High Speed Inking Unit with the settingsmentioned in note 2.9. Check the functioning of the High Speed Inking Unit.Execution1. Adjust the interval time in the display.Materials / testing conditions12345678910IGT AIC2-5T2000IGT High Speed Inking Unit 4(with 4 segmented top roller forconventional inks)Printing disc with coated rubber,85 Shore A, 50 mm (2x)Strips of art paper, code Ka, 55 mmIGT ink pipette (2x)If necessary strips of paper to be tested(55 x 340 mm, 4-6 strips per set ofinks)Inks to be testedDensitometer (if required)Lint free ragsCleaning naphtha710466.410.100(466.003.003)402.333404.009.004408.200 or 408.400Printing forcePrinting speedInterval times between 2 coloursInk film thickness625 N1m/sat choice2.4 μmThe numbers 1 thru 5 are available at IGT Testing Systems.The numbers 3 thru 4 can be obtained as Wet-on-wet Printing Setfor AIC2-5T2000, article number …..2. Attach a test strip on the sector.3. Turn the sector into starting position.4. Apply 2.4 μm of both inks to two separated segments of theinking unit and distribute the inks (indication: 2.4 μm for artpaper). See note 3 or the manual of the inking unit.5. Place the printing discs on the printing disc shafts of thesegments ofthe inkingunit and inkthe discsduring thepreset time.6. Take thediscs fromthe inkingunit andplace themon theprinting discshafts of thetester: the 1stcolour at thetop shaft andthe 2nd colour atthe bottom shaft.7. Press one of the side buttons to start the motor.8. Move the printing discs into printing position against the teststrip.9. Press the other side button as well to make a print (also keepboth buttons pressed during the interval time).10. After the sector has stopped in the end position, release theside buttons.11. Move the printing discs out of printing position12. Remove the test strip from the sector.13. Take off the printed paper strip from the sector.14. Remove the printing discs from the tester and clean themwith the rags and naphtha.15. Clean the rollers of the inking unit or use the next segmentsfor the following test.16. Repeat the points 2 thru 15 for the next test strip in theopposite colour sequence.Fig. 1: wet-on-wet printing |
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