Fiber bonding and formation of paper structure

In modern paper machines, forming process lasts very short, usually less than 1-2 s. As a result, it is very difficult to keep simultaneously the high runnability of the process and maintain the high product quality. Among others, there are four main quality parameters that are essential for the proper paper structure and which must be kept at certain, constant level  

Basis weight refers to the weight of unit area of paper and is usually expressed in gsm (i.e., grams per square meter). The formation describes the uniformity of distribution of fibers in the paper. It can be also considered a measure of the small-scale basis weight variations. Two-sidedness is defined as undesired differences in the properties of the top and bottom surface of paper. 

Industrial paper web forming operation is carried out under dynamic conditions, therefore, paper demonstrates certain differences in its mechanical properties measured in MD (Machine Direction) and CD (Cross Direction). Because of the forming 

The level of fiber shrinkage strongly affects the final paper properties. In general, there are two possible strategies of paper drying  

Restrained drying results in the increase of stiffness, tensile strength and better dimensional stability. On the other hand, free drying results in higher paper stretch and roughness [79]. 

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