Paper Curl Control
Kadant delivers a high level of control with curl and moisture control systems. These patented products include the Steam-Foil® profiling system and Narrow Web Decurler™ profiling system.
Moisture and Curl Control Solutions
The feature that enables both the Steam-Foil and the Narrow Web DeCurler profiling systems to provide high levels of moisture and curl control is its patented Coanda® nozzle. The Coanda nozzle, derived from Kadant’s floatation dryer experience, has been utilized by the paper, converting, and printing industries for more than 25 years. It was the combination of the nozzle with Kadant steam shower technology that provided these breakthrough products.
In both the Steam-Foil and the Narrow Web DeCurler profiling systems the Coanda nozzle is designed to release steam over a curved surface, which is parallel and counter to the web flow. The design provides a high relative velocity between the sheet and the steam over the entire length of the shower. The steam velocity and long dwell time result in high heat transfer rates.
Through design innovation and the use of the Coanda effect, Kadant has overcome the problems typically associated with steam showers. The primary problem is air in the condensing space between the shower and the web, which drastically reduces heat transfer and increases the probability of dripping. The faster the speed of the paper web, the more entrained air will follow the sheet. Hence, larger and faster machines would be expected to feel the effects of entrained air more than smaller machines. Steam Foil and Narrow Web Decurler profiling systems eliminate these effects.
Counter flow steam application creates an incoming edge pressure wall that impedes entrained air. A profileable vacuum chamber is incorporated to remove any excess steam escaping from the leading edge. A preheated steam jacket insures that no dripping will occur. Further, the heated surfaces provide an "instant-on" capability, which allows immediate usage on start-up and after web-breaks. Examples of applications where these profiling systems have been used include:
- Silicone release liners
- Metallized paper
- Specialty coated sheets
- Beverage labels
- Pressure sensitive label