Valmet IQ Web Structure Measurement
Valmet IQ Web Structure Measurement (IQ Web Structure) provides a solid foundation for producing paper, board and pulp with uniform formation and fiber orientation with its accurate machine direction and high-resolution cross direction profiles.
Improved sheet uniformity influences positively not only the strength and dimensional stability, but also optical and surface properties improving printability. The IQ Web Structure gives an instant response to sheets structural changes caused by process adjustments and therefore on-spec quality can be reached faster and startup waste is reduced.
Features of IQ Web Structure
IQ Web Structure measures the uniformity of a moving paper sheet by using high-speed image capture and image analysis technology. High power LED’s are pulsed and the generated light is diffused to produce illumination across the window. The high resolution camera on the other side of the web takes snapshots of the sheet as the light source flashes. Formation index and other numerical data which defines the distribution of fiber flock and void sizes are determined by the sensor’s sophisticated image analysis software according to variations in gray scale levels. Dark spots, light spots and pinholes are also detected and classified by the analysis software. In order to make the analysis as sensitive as possible, the source light intensity is controlled to midrange the gray scale values. The Formation sensor has its own web display, which can be accessed from the operating displays. There the taken pictures are available for more accurate analysis.
Benefits of IQ Web Structure
- Accurate and stable profile measurement for precise control of sheet formation in machine and cross directions.
- Stable fiber orientation profile measurement enables automatic closed loop control of web fiber orientation.
- Sophisticated dirt count analysis gives valuable online information for pulp maker.
- A vast amount of other quality parameters which characterize paper formation including formation index are measured.
- Excellent correlation with Valmet Paper Lab formation measurements and visual perception.
- Measurement gives an instant response to formation variations caused by process operation changes. Therefore, on-spec paper quality can be reached faster and startup waste is reduced.
- Measurement enables formation profile optimization and accordingly energy and furnish costs savings.
- Formation pictures are directly available on the operating displays for the analysis.