Packaging manufacturing process
The granule is mixed with other additives using a blender, which is then sucked and transported to the hopper at the back of the extruder. The granule then passed down through the hopper which feeds into a screw and barrel that has various heating zones that melts the granule.
As the granule passed through the screw it is melted and forced through the die face as a molten material. This creates a ring of polythene which is pulled up from the bottom on the machine via some nip rollers at the top of the machine. In between the die face and the nip rollers, air is used to inflate the polythene to create a “bubble”, which dictates the size of the material.
At the nip rollers the polythene has solidified, and is folded into a layflat sheet. The layflat sheet then passes through a sequence of rollers and will pass through a corona treater if this is present on the machine. At this point the material will be wound onto a core.