Extrusion Shaping
This shaping technique is mainly used to manufacture ceramic items with a constant cross-sectional area: the length of the items is established by cutting the extruded material at right angles to the direction of outflow.
The body used in this process is completely different from that used in pressing: extrusion-ready bodies have, in fact, a moisture content higher than 14–15% and, depending on the raw materials, that figure can be as high as 20–22%.
The extrusion process generally consists of passing a column of body through a shaped (or profiled) opening, known as the extrusion mouth (sometimes referred to a “last mouth of the machine”). From here, then, a shaped material of constant cross-section flows out: this is then cut to obtain the pieces that will be put through the subsequent stages of the ceramic production process.
To be contd…..
