Innovative Measurement Technology for Consistent Print Quality

Ensuring consistent print quality presents numerous challenges for printers. Printing ink, substrates, and the printing machine with its many parameters must be harmonized to achieve the desired print result. Measurement serves as a tool to reduce the multitude of variable parameters and minimize setup effort and machine downtime. By continuously monitoring the printing process, deviations in print quality can be minimized or kept within defined tolerance limits.

Challenges in Metrological Control

For flexographic printing plates, monitoring halftone dot sizes with appropriate measuring devices has been standard for years. Recently, dot surfaces have increasingly been equipped with microstructures to improve ink transfer. Unfortunately, wear affects these microstructures, and previously used measuring devices are unable to detect these changes due to technical limitations.

Anilox rollers have also been subject to metrological control for a long time. Initially, inspections were carried out visually using small handheld microscopes, and ink volume was determined through volumetric methods, where a defined amount of ink was applied to the roller and measured. Today, 3D microscopes are used to determine ink volume precisely, independent of the operator. However, these volume measurement methods can show significant systematic deviations depending on the object being measured. The specifications provided by roller manufacturers are also subject to this issue, making it difficult to compare rollers from different manufacturers.

In gravure printing, inline systems (2D microscopes) are primarily used for monitoring electromechanical engraving. Since the third dimension is defined by the engraving stylus, cell volume can be calculated from the 2D data. However, after chrome plating and surface processing, these volumes can change again. Similarly, in laser engraving of gravure cylinders, multiple process steps can alter volumes. Furthermore, wear and contamination of the cylinder in the pressroom introduce additional challenges.

All-in-One Solution with Unique Features

These examples demonstrate that 3D measurement technology plays a crucial role in stabilizing the printing process. With the DotScope system, consisting of a DotScope 3D microscope and the associated database application, printers can perform comprehensive analyses of flexographic plates, anilox rollers, and gravure cylinders using a single system.

DotScope measuring devices offer unique special features, such as precise measurement of microstructures on flexographic plates in the sub-micrometer range or determining the cutting angles of engraved gravure cylinders. Features such as an objective turret, a focusing knob, and remote-control elements for the PC software significantly increase working speed and ease of use.

Core of 3D Measurement Technology

The 3D measurement process of the DotScope system is based on focus variation, which allows better detection of steep slopes than confocal microscopes or white-light interferometers. The latter use coaxial illumination, where steep slopes appear as black areas due to the lack of light reflection, meaning surface contours can only be interpolated—essentially estimated.

Data Processing and Analysis

DotScope users appreciate the ease of use, fast measurements, practical applicability, and high repeatability and consistency of measurement results compared to similar devices. With just a few clicks, measurement results can be processed further, displayed as reports and comparative analyses, or stored in the database.

The DotScope database application stores all measurements of the used anilox rollers or gravure cylinders and documents their parameters over their entire lifespan. Alarm functions provide the printer with a clear overview of the tools’ condition. Different views, such as tree structures, lists, and detailed displays, simplify navigation and data management.

Conclusion: Increased Efficiency and Productivity

Using a DotScope measuring device ensures faster quality control with significantly less effort. The intuitive operation and smart functions of DotScope save valuable time and significantly boost printing productivity. This allows more focus on truly important tasks.