2 – Converting Processes

The purpose of the converting process is to transform raw materials in the form of polymer pellets or film substrates (including paper and foil) into a final packaging structure. This often involves more than one process or step that may include film formation, orientation, metallization, lamination, coating, printing, winding, and slitting. The basic processes include blown and cast film, extrusion coating and lamination, adhesive lamination, orientation processes (tenter frame, double bubble, and machine direction orientation), and printing. Often there is more than one way to make a functional structure, the choice of which depends on a number of factors such as run length and existing assets of the converter. This chapter briefly describes the major converting processes, their key components, and processing parameters that affect the properties of the final product.