Winding is a crucial step during film production. The best film quality can be ruined if the winding process is not perfect. Moreover different film types have various characteristics and consequently require different solutions for an optimal winding result:
Brückner uses the “Oscillating Edge Trim” method in order to provide best winding results, e.g. for PP, PET and PA films.
Upgrading older or non-Brückner lines with the Oscillating Edge Trim and/or Winder Oscillation is a good way of improving winding results.
PP film sometimes comes along with high edges on the mother roll, since film edges tend to raise depending on the sharpness of the cutting. The deformation which therefore arises at the edge can cause flutes on the contact roll. The Oscillating Edge Trim technology avoids this situation.
What’s behind all this? The edge trim knife is not fixed, but oscillates approximately 5-10 mm to the left and the right. It cuts waves along the film edges which then prevent the edges of the layers on the mother roll from lying directly on top of each other. During the winding process the film edges are shifted between the layers and therefore do not build up. Consequently, there are no flutes on the contact roll. It can evenly press on the winder across the whole width for best winding results.
Oscillating Edge Trim is mandatory for PET and PA film production; however, these films pose an additional challenge: Die lines on the film may build up to visible elevations at the winder since they are always in the same position on the mill roll.
Brückner’s recommendation is to synchronize the oscillating edge trim unit with the winder, i.e. they both move parallel to the left and to the right. Since the film comes in a straight line and the edge trim knife and the winder are both shifting, the existing die lines can be distributed more evenly across the roll width, which avoids any elevations on the film.