The German company Sama, member of the Sacmi Group and leading international manufacturer of machines and systems for the tableware industry, is renowned for the high level of technology used in its products. A prime example is Sama’s vacuum extruder. Both in classical and technical ceramics vacuum extruders are used to obtain homogenous, compact bodies without air inclusions. These machines have two main ranges of application: the first is the extrusion of profiles, which are finished by heat treatment and cutting to length, the second is the extrusion of semi-finished products, known as pugs or blanks, which are shaped to the required geometry.
The essential qualities of vacuum extruders include a high drive power to ensure sufficient compaction of the body, despite its low plasticity, and high abrasion resistance of the augers achieved by treating them with abrasion resistant materials. Other advantages are good and quick accessibility of the augers for regular cleaning and cooling of the extrusion cylinder.
The largest and strongest vacuum extruders, equipped high drive powers, are used in the insulator industry. Optimal compaction during extrusion is only attained with an extruder which, in addition to having sufficient drive power, also enables the operating speed to be controlled and adjusted. This is why extruders for the insulator industry are equipped with frequency-controlled drives. During operation, overheating of the bodies is avoided by water cooling in the double jacket of the main extrusion cylinder. In order to achieve the high compaction that this technology is capable of, the pug diameter must be suitably proportional to the auger diameter.
To avoid the formation of air in the body, vacuum extruders are equipped with special measuring instruments for a precise and constant control process. The pressure and temperature of the body are measured at the cone before the mouthpiece.