Fournisseurs de lignes d'extrusion de film plastique

Blown film vs cast film extrusion — which process for your application?

Blown film extrusion produces tubular film by extruding a plastic melt through an annular die and inflating it into a bubble with internal air pressure. The bubble is cooled by external air rings and collapsed into flat tube, then wound onto rolls. Blown film is the dominant process for LDPE/LLDPE bags, agricultural mulch film, heavy-duty sacks, and multi-layer barrier film. Advantages: no edge waste (tubular film gives a bag directly), good biaxial orientation improving toughness, suitable for multi-layer co-extrusion with up to 9 or more layers. Limitations: slower output compared to cast film; thicker gauge control is harder below 15 microns. Cast film extrusion produces film by extruding a flat sheet through a T-die and quenching it on a chilled casting roll, then winding. Cast film is faster, produces better optical clarity (for stretch film, cling film, overwrap), and achieves thinner and more consistent gauge (down to 10 microns or below). Used for stretch wrap (LLDPE), cast polypropylene (CPP) film for lamination, and food wrap. Limitations: edge trim waste; less biaxial orientation limits toughness for heavy-duty applications. For agricultural film, refuse sacks, and heavy duty bags: blown film. For machine stretch wrap, CPP lamination film, and cling film: cast film.