Geotextile applications would benefit from IsoProDyn & IsoProfile

01 Apr '09

5 min read

The dynamic batt shaping technologies all work with methods to adjust the web weight prior to entry into the top carriage of the crosslapper and therefore we can assume that the batt will reflect the overall averaging of web alignment within the folds of the batt. It would seem logical to believe that if one were able to generate uniform cross directional weight uniformity that we would also generate uniform physical performance values, but this is an incorrect assumption.

This assumption that weight uniformity equates to physical performance uniformity (tensile) is indeed incorrect as dynamic batt shaping is focused on generating web weights which pulse between a min/max weight range to effect the development of a batt weight profi le to offset the effects draft has on fiber migration and the reduction in felt width generated from batt forming through bonding to the winder. The modulation of web weight to meet the desired batt weight profile does not significantly change fiber orientation in the web to have any impact on the tensile uniformity of the needled felt.

The orientation of fibers in the web is largely control led by the card although systems such as WebMax & CV1 draft the carded web (typically with one web condensed) to help create the required batt shape to counter the effects of draft whereas ProDyn adjusts the web weight on the doffer (parallel and/or condensed), thus maintaining the fiber orientation of the doffed web. It would be reasonable to assume that in applications where higher MD performance is required to equate a balance in MD/CD, or is required to achieve higher tensile strengths that more draft would be applied in the consolidation and bonding process to pull the fibers toward the MD orientation.

This of course will impact the batt width due to the tension differential between the fibers at the center of the batt and those who are closer to the edge of the batt. The balance in fiber tension decreases with distance from the center and proximity to the edge of the batt, thus impacting not only the weight distribution of the batt due to this imbalance in fiber tension and fiber migration but also the consistency in fiber orientation in the batt.

This variance in fiber tension and migration as the width shrinks due to draft translates into inconsistency of physical properties as measured across the width of the finished needlepunch felt.

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