Basis machine direction control

The mechanical properties of the various erosion control fabrics are reported in Table 11.5. Values for the standard deviation of the thickness and basis weight of the peanut fiber fabrics are unavailable. Due to the limited amount of peanut fabric produced and the fact that the webs were partially created by hand, they were tested only in one direction, labeled as the machine direction in Table 11.5. 

Automation is a system in which some action happens as a result of another event and without human intervention. We use the term to refer to robots and the control of machines in manufacturing, but automation is much more than just manufacturing. Automation is present in many aspects of your personal life on a daily basis. Our lives are better as a direct result of automation. 

Automation by fast, stable and accurate control loops for consistency, flow, pressure and level is elementary for providing the necessary constancy in the approach flow system. Variations in pressure for example will mainly directly influence the MD profile whilst stock consistency deviations will affect both CD and MD basis weight profiles. In addition the retention on the paper machine and the chemical conditions of the water systems must be kept constant. Here a retention control loop is standard in many appHcations keeping the white water consistency constant by adapting the quantity of retention agent added. Controls for filler, color, air content, cationic demand or zeta potential are also available today. Combining the different controls to a total control concept will lead from purely functional controls to control systems which also address quality and production issues. 

Some controls in the process are more complex than just PID control loops. One example is the wet end control which ensures uniform process conditions in the approach flow of the paper machine and in the forming section by maintaining constant consistencies, gas content, charge and other parameters. It involves e. g. special software tools (soft sensors) using wet end data instead of direct measurements to predict basis weight during start up of the machine, when the paper has not yet reached the reel or the quality measurements. Such, wet end controls not only reduce the start up time of the process, but also minimize the consumption of chemicals, i. e. only as much retention aid is used as is really needed to reach a required retention level in the forming section. 

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