In recent years, films have become thinner to improve quality and performance and the line speed is getting faster than ever. These films are very sensitive and fine scratches of the film are no longer acceptable in the market. Such scratches are often caused by slippage between the film and the rollers when air is trapped in between.
Micro-grooved roller surface allows air to escape from the grooved space, so the running speed gap between the film and the roller rotation is minimized. Because the grooves are in micron sizes, it will not leave grooved marks even to the sensitive film surface.
Normal flat surface Roller (Movie Left): Roller rotation remains slow (film is slipped) even at higher conveyance speed. Micro-grooved Roller (Movie Right): As the conveyance speed increases, the roller rotation also becomes faster (the slip of the film is suppressed)
A number of rollers are built into the equipment that produces and processes films. If there is no parallelism between the rollers, a tension difference is generated in the width direction, and wavy wrinkles (troughs) are generated diagonally with respect to the traveling direction of the film.
In the transport of thin film, when the transport tension is set to the same level as that of thick film, the film extends in the transport direction, causing wavy wrinkles parallel to the transport direction. These wavy wrinkles may break when passing through the rollers, which greatly reduces the commercial value of the film.
Concave rollers are inverted crown-shaped rollers with a narrow center and thick end. Compared with the center part, the peripheral speed becomes faster as it goes to the end due to the difference in outer diameter. Film has the property of moving toward the edge with a high peripheral speed. The film also has the property of entering in a direction perpendicular to the roller on the downstream side. These two effects widen the film and reduce wrinkles.
Concave Roller is available both with rubber rollers and metal rollers. We can also propose an installation position from the roller layout drawing. Please feel free to contact us.