VIENNA, Dec. 12 -- Foam extrusion machine maker SMS Folientechnik Gmbh has developed an improved process for manufacturing foamed film and sheet. The key feature is two cooling extruders in parallel configuration, providing a cost-efficient solution to the increasing demand for higher cooling capacity � especially for the manufacture of foams with alternative foaming agents.
Cooling of the melt is critical in manufacturing foam products and conventional systems have been equipped with cooling extruders of larger and larger dimensions to increase throughput, according to SMS Folientechnik. Screw diameters of up to 400 mm are common in high-performance lines with an output of 1600 kg/h or more. Apart from the relatively high capital investment, the main drawback of this conventional solution is the lack of melt temperature homogeneity, says the supplier. Homogeneous melt temperature is said to be important for manufacturing a high-grade finished product.
In the new patent-pending process, the cooling of the melt is taken over by two extruders in parallel configuration. Upon leaving the primary extruder, the melt is divided into two-part streams, optimally cooled by the specially designed ExCool screws in the cooling extruders, and then the two separate streams are reunited.
SMS Folientechnik has delivered the first XPS foam sheet line equipped with the new technology. The line offers output of 1500 kg/h and is equipped with a 180-mm melting extruder. Through the two parallel cooling extruders, each with a 200-mm screw diameter, the melt is optimally processed and homogeneously cooled. It then passes into the die for manufacturing foam board at up to 200-mm thickness, the company said.
Besides new manufacturing, SMS Folientechnik offers the new process for retrofitting existing lines. The parallel cooling process is a cost-efficient option for manufacturing CO2-foamed boards which require high cooling levels.