Converting companies are companies that specialize in modifying or combining raw materials such as polyesters, adhesives, silicone, adhesive tapes, foams, plastics, felts, rubbers, liners and metals, as well as other materials, to create new products.
Materials such as paper, plastic film, foil and cloth often are produced in long, continuous sheets that are rolled up for more convenient handling and transportation. These rolls of material vary significantly in size and weight — ranging from wide and weighing as much as several tons. The converting industry takes these continuous rolls of thin, flat materials — known as webs — threads them through processing machines (such as printing presses, laminating, coating and slitting machines) and converts or changes the web of material into an intermediate form or final product. For example, a converter’s equipment might take a web of plastic film, cut it into lengths, and fuse their edges, thus converting it into plastic bags. This activity is known as web processing.
Typical converting processes include coating, laminating and printing. Coating technologies can include hot melt coating, gravure coating, curtain coating and slot-die coating. The most common printing techniques are flexo printing and rotogravure (gravure) printing. Both print processes are suited to high speed roll-to-roll processing.
Many converting companies will process large diameter, wide rolls of material as this increases the converting efficiency by minimising changes. On completion of the converting process the rolls may be cut into smaller rolls on a slitting machine or a sheeter. These rolls or sheets are then a convenient size for handling on packaging and other machines. Further processes such as collation may occur after sheeting.
Depending on the specially of the converter, many other processes might be involved. These might include: shearing, die-cutting, laser cutting, heat sealing, laser converting, perforating, Ultrasonic welding, Surface finishing, etc.