The geometry of the conveying elements enables a good transport of the product through the extruder. Each conveying element is characterized by its number of flights, its length in millimeters, and its pitch. The pitch is defined as the axial length in millimeters, required for a complete thread. Conveying elements with a large pitch have a greater conveying effect than those with a small pitch. These elements are used to forward the material e.g. at feed openings, in order to avoid that pressure increases excessively at the openings.
Kneading elements are mostly used for dispersive mixing, but they are also used for distributive mixing processes. They consist of kneading discs with a certain thickness. Like the conveying elements there are several parameters by which the kneading elements are characterized. These parameters include the number of flights, the staggering angle between sequential kneading discs (in degrees), direction (clockwise or counter-clockwise) and the element length (in millimeters) . Except for their mixing properties, kneading elements can also be used for devolatilizing and draining of the substance. Kneading elements with a small staggering angle are also capable to forward the material through the extruder, but therefore their axial mixing effect is less intense. In general, kneading elements with a smaller disc width provide a better distributive mixing than those with thicker discs, which provide a better dispersive mixing.
|Screw Diameter (mm)||22||35.6||41||51.4||62.4||71||93|
|Screw Speed (rpm)||600||600||600||600||600||600||600|
|Motor Power (kw)||4||18.5||30||55||90||132||315|