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Cast films were thinner, more flexible and lasted longer. But many strides have been made in calendered films to challenge those traditional notions while maintaining an affordable cost. With today's advancements, the new calendered films have greatly improved performance and have overcome many prior insurmountable hurdles in the US market.

The production process for calendered film once resulted in an inexpensive yet thick material that was better suited for applications on flat surfaces; however, today's calendered films are thinner, glossier, conform better and with less shrinkage, while still maintaining that cost advantage. Today, a high-performance calendered film can satisfy sign makers' needs for a wide range of applications.

Different Components
To create calendered film, polyvinyl chloride (PVC) is mixed with plasticizer to make a flexible film along with other additives to achieve the desired physical properties, such as stabilizers, lubricants, pigments and processing aids. Although PVC is the primary ingredient in calendered films, each additive plays a vital role in changing the properties.

Production process of calendered film
Each film has its own formulation. Based on this formulation, the raw materials are mixed together to a dry blend and fed into the extruder where the mixture fuses together to form the melt. Via a conveyer belt the melt is transported to the mill.

The mill consists of two counter rotating rolls. Due to pressure and heat, it flattens out the melt, makes it more homogeneous and prepares it for the calender rolls. Before that, a metal detector detects if there is any metal contamination in the strip.

In the calender section, the strip goes through the first gap and will be flattened out into a film. After each gap the temperature and the uniformity will increase. The film also becomes thinner and wider - according to the customer's specifications.

Next comes the embossing station, where different patterns and gloss levels can be applied to the film. Each embossing requires a special embossing roll which needs to be installed for the desired final surface finish.

Now that the film has received its final dimensions and surface, it can be cooled down and transported to the last process stage of winding. Before the film can be wound, the thicker edges of the film need to be trimmed off.

The cooled and trimmed film is then wound to a master rolls and put in metal racks for further quality control and finally shipping.

Sophisticated production and process technology
Present-day's successful calendered film manufacturers have continuously refined and improved the whole production process. This started with the further development of the base formulation, which led to a higher film performance regarding mechanical properties, durability and color consistency.

Furthermore in the recent years investments in new equipment and process technology they have driven significant improvements in this complex manufacturing process. Today sensitive and intelligent control systems monitor and measure numerous parameters which are crucial to film quality. These parameters are related to the exact machine set up, but also to the film itself which runs through the calender. For example film properties like thickness, color, width, gloss level and so on are constantly controlled. As an result, the whole manufacturing process has gained much greater uniformity, and the films could be specified even tighter and the overall quality has become more consistent.

The results have boosted the performance of calendered vinyl: they have an excellent layflat, shrink less and are thinner (2.0mil) and glossier than ever before.

Both calendered and cast films certainly have their appropriate places in the market, but calendered films have especially made significant advancements. Applications that were once only reserved for cast films, are now open to calendered films. And while calendered vinyl films remain the more affordable option, they are not necessarily the inferior option anymore.