Volumetric metering

Metering with profiled rods is referred to as volumetric metering. During the metering process, the points of the profile are almost in contact with the sheet or backing roll. The precise coating volume is determined by the geometry of the profile, i.e. by the rod profile cross section and distance.

The design of the profile also affects quality of coating and rod life. Based on our experience, the profile can be optimized in terms of coating volume, rod life, and quality for each specific application. Today, profiles covering a metering range from 3 – 150 ml/m are available. The most popular metering ranges are between 15 – 50 ml/m.

On profiled metering rods, the linear load serves more as wear compensation than for setting of coating volume. Ideally, after installation of a new metering system the start-up is performed at high contact pressure, which is continuously reduced until minimum pressure is reached. This ensures a consistent coating volume at maximum service life of the metering system.

Test series, comprehensive laboratory evaluations, and above all decades of practical experience, provide our customers with optimized coating processes with the following results:

• Increased coating evenness = increased quality
• Longer service life = increased economic efficiency
• More intelligent design = new possibilities for innovative paper products

Why larger metering bar diameters increase production disproportionately

Generally, 10 to 15 mm diameter metering rods with smooth surface are applied in direct coating, or with profiled surface in the filmpress.

Depending on the content of abrasive components in the coating media, a service life of two to four weeks can be reached. This practice applies to paper machines operating 24/7 throughout the world. However, since it prevents innovative advantages, the motto "Never change a running system" is counter-productive in an increasingly tougher competition.
When each additional production hour and waste minimization count, metering rods must offer a longer service life and less frequent revision cycles. A simple technological solution is the use of metering rods with a larger diameter, allowing above average run times.

Profiled metering rod diameters - A question of the correct size

We have a comprehensive product portfolio that allows us to offer optimum metering rods to suit any application and production conditions.

The diameters of profiled metering rods start at 9.75 mm and go up to 25 mm. Various groove cross sections and spacing as well as sinusoidal and trapezoidal geometries are available for the profiling. This makes it possible to design the geometry of the metering system specifically to suit the required coating application.

Application example for profiled rods - Surface sizing with filmpress

This is without doubt the most important application for the profiled, chrome plated metering rod with a diameter ranging from 10 to 15 mm.  In contrast to smooth metering rods, the profiled rod can be applied in an extremely broad range of viscosity. Thus, it is also ideally suited for very low viscosity starches. In 24/7 operation, a service life of up to four weeks can be easily achieved if the starch is largely free from abrasive components.

Contour coat for folding boxes and high-quality paper grades

When the focus is on very uniform color distribution and coverage, the increased application of profiled metering rods is interesting to note. Compared to traditional air knives or modern curtain coaters, today it is possible to achieve coating results of comparable quality with profiled metering rods. The correct setting of all parameters can produce an economically attractive service life, particularly with ceramic coated rods.

Rod ends (for smooth metering rods) - Solutions from start to finish

Not only the metering rod but also the rod ends are decisive factors in determining the quality of the coating. Our rod ends take this fact fully into account.

We offer six customized rod ends for various types of systems or mounting points. Their common features: perfect fit, high quality, easy to install.