In fact, the overall focus in crosslapped nonwovens manufacturing has been more focused on cross width weight uniformity than speed, due in large part to an overall stabilization of doffing speeds within a window of 90-120 m/min. This general range of doffing speeds is related to the capabilities of the crosslapper and the extended speed range required in crosslapping when using the advanced batt shaping technologies, which require the crosslapper to have lay-down speeds that are dramatically higher than the doffer speed.
The state-of-the art in dynamic batt forming with technologies such as ProDyn, WebMax and CV1 have brought the CD weight uniformity to CV values between 1-4%, depending on the technology employed, the finished weight, draft and needled parameters within the manufacturing line. As with the development of profiling technology, which was first introduced in 1991, the introduction of ProDyn dynamic batt shaping in 1999 was a technological leap relative to using profile technology.
One of the additional developments in crosslapping has been in the control of the web as it enters the top carriage. This ability to control the web at higher input speeds has eliminated web control problems associated with the top carriage as it moves toward the card, thus enabling higher doffer/feed-in speeds.
The focus in technology has actually focused in other areas where increases in operating efficiency or reduction in maintenance cycles has been where many advances have taken place; all of which help to reduce the manufacturing cost and hopefully enable the nonwoven manufacturer to maintain a competitive advantage of the competition.
Thus, with these dynamic batt shaping technologies, the overall focus has been on cost reduction via fiber savings generated through better CD weight uniformities and optimization of operating efficiencies through better fiber management systems in web forming and overall fiber processing.
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