Valmet IQ Web Caliper Measurement

The accurate scan averages and high-resolution CD profiles measured by Valmet IQ Web Caliper Measurement (IQ Web Caliper) provide a solid foundation for Valmet’s cross-direction caliper profile controls for paper sheets and machine-direction caliper control for boards. Digital signal processing, coil construction and platen pressure control ensure maximum accuracy.

Valmet IQ Web Caliper Measurements

Features

The variable magnetic field established between a stationary energized coil and a floating platen is a very sensitive indication of sheet caliper. As the sheet caliper varies, the magnetic linkage between the two elements varies as well.

The high frequency energized microcoil system in the detector head is sapphire coated for long life. Temperature-compensated coil construction minimizes temperature sensitivity.

The low-mass floating platen is attached to a pliable membrane supported by an air cushion. This low-inertia design allows the platen to respond quickly to caliper variations. The contact pressure is precisely and quickly controlled by a dedicated microprocessor to exert a steady pressure on the sheet for stable readings. 

The floating platen’s mass and contact area are customized to the grade of paper for the best performance from lightweight papers to heavy boards. The platens are coated with a sapphire composite material for long lifetimes.

Benefits

  • More accurate and stable on-sheet measurements for precise control of MD and CD properties.
  • Precise streak control using 1 cm resolution profiles, available after the very first sheet scan.
  • Low mass, light-touch sensing element does not affect sheet runnability.
  • Faster on-spec quality and reduced startup waste.
Caliper measurements
Valmet IQ Optical Caliper Measurement

Valmet IQ Optical Caliper Measurement

Sub-micron caliper measurement accuracy at the highest resolution and scanning speed lead to more accurate and stable onsheet measurement and more precise control of MD and CD properties.