SUMMARY:Within both the paper and paperboard industries, real time monitoring and measurement of surface roughness of a paper moving at high velocities is an important and challenging area of research. The uniform surface, for an entire production, can be effectively achieved by monitoring and controlling the paper surface roughness, in real time during the manufacturing steps. Presently the majority of paper industries rely on traditional laboratory profilometers. The obvious limitations of lab profilometers are that these are slow, do not measure the quality of entire reels but rather deal with only a few small pieces of samples taken from the end of the reels and it is difficult to make any possible correction in the production lines without knowing the online roughness data. To eradicate the disadvantages associated with conventional measurements, an online prototype instrument has been developed that measures the surface roughness during the manufacturing steps, and is based on a line of light triangulation technique. The prototype technique will be of assistance in ensuring tight process control in order to maintain both a better and a uniform quality throughout the entire production. It measures the whole reel, meter by meter, in traditional units of roughness and is also capable of characterizing the topography in a wide range of wavelength spectra. The article presents the online analyses results obtained from the developed prototype. The real time measurements, in a paperboard pilot mill, have successfully characterized and distinguished 16 different grades of newspaper and paperboard reels including reels which have the same family of quality grades and materials.

No abstract

No abstract

No abstract

SUMMARY:Quality control is an important issue in the paperboard industry. A typical sheet of paperboard contains a core of cellulose fibers [C 6 4 ]. One of the major properties of a good quality paperboard is the consistency of the expected ratio between the thickness of the core and the coating layers. A measurement system to obtain this ratio could assist the paperboard industry to monitor the quality of their products in an automatic manner.In this work, the thicknesses of the core and the coating layers on a paperboard with coating layer on only one side were measured using an X-ray imaging technique. However, the limited spectral and spatial resolution offered by the measurement system being used led to the measured thicknesses of the layers being lower than their actual thicknesses in the paperboard sample. Suggestions have been made in relation to overcoming these limitations and to enhance the performance of the method. A Monte Carlo N-particle code simulation has been used in order to verify the suggested method. ADDRESSES OF THE AUTHORS:Salim Reza (salim.reza@miun.se), Börje Norlin (borje.norlin@miun.se), Jan Thim (jan.thim@miun.se), Christer Fröjdh (christer.frojdh@miun.se): Department of Information Technology and Media, Mid Sweden University, Holmgatan 10, 851 70, Sundsvall, Sweden. Corresponding author: Salim Reza. At the present time, in the paper industry, mechanical and optical methods, such as Bendtsen and light triangulation methods are often used for surface profiling in order to observe the roughness and cockling of paper and paperboard surfaces. However, with these methods, it is not possible to measure the ratio between the thickness of the core and the coating as well as the homogeneity of the layers. Spectroscopic X-ray imaging could be a tool to obtain this ratio and, incorporating the imaging in an online measurement situation, the information could be sent back to the control station in the production line for quality adjustment. This article presents a method to separate the cellulose and the CaCO 3 layers (Norlin et al. 2009) on paperboards (Fig 1a) in terms of thickness using spectroscopic X-ray imaging.The proposed method can be used to replace the Ammonium Chloride (NH 4 Cl) burnout test (Dobson 1975) method, which has been widely used with regards to paper/paperboard quality inspection. In the burnout test method, a paperboard sample is treated with an NH 4 Cl test solution (25 g/liter NH 4 Cl in a 50/50 volume mixture of 2-Propanol/water), after which it is placed under a heat gun for two minutes to burn it out. The burnt sample (Fig 1b) is then examined for color change/development.