SML has developed winding shafts that help to considerably cut the costs and to minimise the carbon footprint of cardboard cores.

SML’s new winding shafts are especially designed for cardboard cores containing a high share of recycled paper as well as for cheaper paper cores. “The focus of this unique development is clearly on the reduction of costs by minimising the amount of cardboard that is needed for cores to wind LLDPE based stretch film”, Thomas Rauscher, product manager at SML, explains.

“Just to illustrate this idea: With this eco-friendly solution we were able to reduce the weight of the cardboard core by approx. 20 %. A conventional core for machine roll production weighs 1.2kg. Using the new shafts you can go down to 1kg or even less,” Rauscher explains. For hand rolls this would be quite similar: instead of conventional 310g cores, cores of just 250g could be used.

Centering the cardboard core on the shaft
The underlying concept of SML’s new and exclusive winding shafts sounds quite simple: The new shaft uses a lot more clamping devices to fix the cardboard core than conventional winding shafts. This makes it possible to center the core in a much better way. On top of that, the pressure to fix the core during the winding process can be reduced.

Due to the reduced pressure, the cardboard core requires less flat crush resistance. A lower requirement for the flat crush resistance can be utilised in different ways: by using more recycled paper for the core, by reducing the weight of cardboard core using cheaper paper or - very simply – by reducing the thickness of the core.

SML’s new types of winding shafts are available for 3-inch, 2.5-inch as well as 2-inch for the Winder W4000 and fit perfectly with the SML stretch film line brands MiniCast, EcoCompact and SmartCast.

Redlham, 16.06.2021