Ohio-based Nordson Corporation has released the PolyStream™ Assembly, a new patent-pending motorized back pressure valve assembly for extrusion coating and laminating, a system designed to provide closed-loop control, minimizing human error and the possibility of injury when making manual adjustments.
The drive for the valve responds to a controller that receives a continuous flow of signals from a pressure transducer, causing the valve to open at varying degrees in accordance with whether back pressure is trending too high or too low. When the valve reaches its limit of opening as a result of excessive contaminant buildup on the filtration screen, an automated warning indicates that it is time to change the screen.
A human / machine interface (HMI) enables the operator to specify process conditions or to use specifications from a recipe. The valve assembly can be run manually, although Nordson recommends automated closed-loop operation.