Comexi/QuadTech – Closed-loop color control for flexible package printing

SPAIN/USA • Since 2016, both companies have joined forces in the investigation and development of new color control management technologies for the flexible packaging industry. This close collaboration resulted in the adaptation of QuadTech’s Color Control with SpectralCam, and its extension from paper and label printing to the printing of flexible packaging.

The Color Control with SpectralCam system brings advantages for standard applications on various flexible films. Comexi and its offset business unit team recognized the advantages that the closed-loop colour control system brings to flexible packaging printing. As this typically runs reel-to-reel, it is not possible for press operators to take a printed sample for exact color check. That was one of the main requirements that the two companies recognized, and this drove the implementation of Color Control with SpectralCam for flexible packaging printing.

QuadTech’s system brings automated precision for achieving color targets. Spectral-based, closed-loop color control means faster, easier color OKs, reduced make-ready time and enhanced productivity. The SpectralCam is a 31-channel spectrophotometer that accurately measures spectral response over micro color bars, then calculates L*a*b*, ΔE, Density and ΔDensity – all at full press speeds. The patented web stabilizer uses ISO-conforming black and white reference tiles—a constant, known backing—that moves with the camera to provide consistent spectral response. Short bursts of pressurized air are used to bring the substrate into close proximity with the ceramic backing tiles for precise color measurement.

Patented adaptive control methodology adjusts the press to maintain accurate control over four-color process, extended gamut and spot colors throughout the run. On Comexi’s Offset CI8 running seven-color process, also known as “extended gamut’ printing, a spectral system that measures color is preferred over a density measurement. SpectralCam is QuadTech’s third-generation spectrophotometer.

Ink fountains of offset presses have a range of narrow ink keys across their entire width. The opening of each individual ink key can be remotely controlled by the operator, in this way the operator can react on local or general color variations, as they are indicated by the color measuring systems. The “closed-loop“ Color Control system can make the press operator’s corrections by automatically adjusting the ink keys based on data provided by the SpectralCam.

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