Ink viscosity is one of the most important factors for achieving high and consistent color quality in gravure printing. Despite the sophisticated measurement and control systems built into today’s printing machines, ink viscosity is still frequently measured with inefficient and inaccurate methods, such as efflux cups and falling ball viscometers.

The variability of these measurements makes consistent color quality difficult to maintain. They underscore the need for a viscosity measurement and control system that can help operators obtain the very best color quality over the very long print runs that are characteristic of gravure.

Viscosity plays an important role in the final quality of printed matter. Ink layer thickness and flow behavior deviate from the optimal values when the viscosity is incorrect, resulting in substandard print quality. Poorly adjusted ink viscosity can also lead to excessive ink consumption and unnecessary costs. Accurate viscosity measurement and control can substantially improve print quality, while reducing waste and improving efficiency.

Even though methods are now available for continuous inline measurement of ink viscosity, many are sensitive to contamination, installation variables, and baseline shifts, which can impair operator confidence and cast doubt as to their long-term reliability. We will show the value of stable, easily cleanable, and repeatable viscosity sensors in printing processes. We will support our conclusions with experience and data from printers who have been using our sensors and automation systems over a period of several years.

A further benefit of high-accuracy viscosity measurement and control is online, automatic, dynamic control of color accuracy within previously unattainable narrow limits, thus ensuring high and consistent print quality over even the longest runs.

• Why is ink viscosity a crucial variable to be controlled in printing presses?
• Technical challenges in online ink viscosity control
• Installation on printing press
• Gravure challenges
• How viscosity affects the color precision and quality in printing? Benefits of tight viscosity control for print quality and ink economy
• Challenges with traditional viscosity measurement units
• Benefits of printing press automation (Industry 4.0) and predictive tracking control in terms of quality and efficiency improvements, VOC emissions and waste reductions

Rheonics sensors have built-in temperature measurement, permitting the temperature of the ink to be monitored. This permits the viscosity readings to compensated for temperature, which is essential for ensuring consistent production through typical daily and seasonal temperature variations.

There are many benefits to using an inline viscosity sensor like the SRV for printing applications. and some include:

• Works accurately in most coating systems with a broad range of ink compositions and viscosities – water-based, solvent-based, UV inks, metallic inks etc.
• Maintains the set ink viscosity, extremely responsive to fresh ink additions
• Rugged, hermetically sealed sensor head. The SRV can be cleaned inline with all standard CIP processes, or with a wetted rag, without the need for disassembly or recalibration
• No moving parts to age or foul with sediment
• Insensitive to particulate matter; no narrow gaps to foul with particulates
• All wetted parts are 316L stainless steel—meets sanitary norms with no corrosion problems
• Certified under ATEX and IECEx as intrinsically safe for use in hazardous environments
• Wide operational range and simple integration—Sensor electronics and communication options make it extremely easy to integrate and run in industrial PLC and control systems.