ASK THE EXPERTS: The EASY-COL revolutIon

21 January 2010



Markus Bauschulte, technical sales director, printing and finishing, of Windmöller & Hölscher, explains how its EASY-COL system has revolutionised the process of ink preparation and supply as well as colour matching on press


Windmöller & Hölscher has conducted a detailed survey of flexographic printing converters around Europe to establish where most of the set-up times are generated.

The investigations prove that up to 50% of time and work spent on press change-over goes to ink preparation and supply as well as colour matching, correction and re-mixing.

Although most of the participating companies have invested heavily in colour matching and ink store management systems, colour matches on press would take 30 to 60 minutes, with the machine down and capacities idling.

Having the latest ink store management equipment, these companies can ensure that all of the ink is made to the correct colour shade when prepared for the press. So why is colour matching still such a big contributor to the change-over process?

According to the survey, final fine tuning of colours on the press cannot normally be avoided due to tolerances inherent in the flexo printing process. There is no way of eliminating variations in the ink transfer performance of anilox rollers and plates or in the substrate, however insignificant they may be. Further research with the participating companies has highlighted three problem areas:

¦¦ Ink weighing: The amount of ink within the system is unknown and only estimated by the operator.

¦¦ Ink formulation/colour matching: The colour shade corrections are based on the operator’s experience.

¦¦ Mixing and dosing of corrective ink: The amount of ink required to correct the colour shade is estimated by the operator.

The W&H EASY-COL system consists of three modules that can be combined or supplied separately to eliminate these problems for both water and solvent based inks.

Ink weighing

The main target of the in-line weighing system is to display the actual amount of ink for each printing station, including doctor blade and pipework. This figure is needed to calculate the amount of ink needed to correct to the required colour shade. In addition, in-line weighing systems display at the very beginning of a new production run how much ink will be needed for the job. They also show if the ink quantities will do for the job or whether subsequent additional ink mixing will become necessary, while at the same time the expected quantity of left-over inks is calculated. Residual ink quantity is notably reduced and the cost of left-over ink storage, management, re-mixing and disposal minimised.

Ink formulation/colour matching

The EASY-COL ‘ink formulation’ module measures the first proof print spectrometrically and automatically detects any deviations from the target colour location. In conjunction with ink weighing, the system calculates the correction tonal values and the quantity of ink required to attain the colour target. The system is capable of signalling instantaneously if the inks currently in use cannot be corrected relative to the target colour location.The ‘ink formulation’ module works on the basis of fresh inks but may also use inks left over from previous orders whose formulation may not be known.

Mixing and dosing

Upon specifying the ink formulation, the exact amount of ink needs to be mixed and precisely metered for colour correction. At best, the printer can make use of the W&H ink mixing station to compose the correction ink according to the appropriate correction recipe. Another alternative to use is an integrated scale for adjusting the inks in accordance with the correction recipes and adding them manually to the ink supply system of the press – a rather unsophisticated, though admittedly practicable procedure.

Summary

Ink supply and colour matching represent major saving potential. Long makeready times caused by manual colour matching procedures and resulting residual ink waste can be effectively reduced with EASYCOL. The three modules provide exact definition of the required ink quantities, they determine colour corrections for the desired target colour location reliably and ensure perfectly precise dosing of inks. Used in conjunction with W&H printing presses, EASY-COL revolutionises the process of ink preparation and supply as well as colour matching on press.


Markus Bauschulte Markus Bauschulte

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Windmöller & Hölscher

Markus Bauschulte Markus Bauschulte


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