Auger extruder

Single auger extruders. The single auger extruder with one auger shaft represents the standard design extruder. 

The following table shows the main components of a simple auger extruder and their most significant design versions ... 

In the 1960s Messrs. Uniceram SA of Marseille, France, built a hydraulically-driven piston extruder for the stiff extrusion of structural clay products, combined with a de-airing double-shaft mixer, was operated as a combined de-airing extrusion unit (Fig. 5). On the whole however the piston extruder has been of relatively little importance in comparison to the auger extruder within the field of structural ceramics. 

Frequently expression rolls were combined with an upright or horizontal pug mill or with an inclined-fitted auger extruder, so as to utilize the mixing and homogenising effect of these machines, which of course could not be achieved by the expression rolls (Fig. 7). The first vertical expression... 

There were essentially two reasons for the transition from an upright to a horizontal auger extruder feeding of an upright extruder, which at that time was still effected manually, was extremely strenuous, and the arrangement of the drive - whether at top or bottom - was not without problems. 

Since the introduction of auger extruders from 1855 onwards, that is to say for the last 150 years, the problem of textures/laminations in the extruded bricks has been the main issue in extrusion, even today still not entirely resolved a sometimes controversial subject permanently under discussion and the topic of numerous publications. 

The triumphal march of the auger extruder however was not to be stopped. For all that, a great deal of design work and detail development had to be undertaken to reach today s state-of-the-art technology, which will be dealt with separately in Chapter 2 in much more detail. Around 1870 vertical auger extruders, the so-called suspended extrusion machines , were brought onto the market, to become forerunners of the later sewer pipe presses (Fig. 18). 

For extrusion of very wide, flat clay ribbons the twin-shaft auger extruder was reintroduced in 1994 in the field of structural clay products, whereas co-rotating screw-extruders are used since the late 1970s in advanced ceramic for the production of honeycombs. 

Going back to the first auger extruders, the extruder machine body was separate from the open-type gearbox and drive section until, from 1865... 

Fig. 35 Auger extruder separate machine body and drive section...

Animals provided driving power for the first upright auger extruders. Initially this was in the form of direct drive using a tie beam that was fastened in a beam shoe at the top end of the auger shaft. This system of drive was... 

Fig. 40 Upright auger extruder with bottom drive using transmission and steam engine...

Fig. 41 Auger extruder with 3-step belt puUey...

Fig. 47 Combined de-airing extrusion machine comprising of vacuum doubleshaft mixer and auger extruder, 1937...

J. S. Spreckstruyff of Gouda, Holland, designs a clay mill for the preparation of pipe clay considered the embryo of the auger extruder... 

Horizontal twin-auger extruder with cutter by Randal Sander. Borie builds an extrusion machine in Paris... 

The Universal Patent Brickmaking Machine, a suspended auger extruder designed by Carl Schlickeysen (auger for plastic bodies)... 

First English auger extruder by Bennet Sayer Ltd., Nuns St., Derby... 

Rohrmaim succeeds in extruding cooling spirals on an auger extruder from a stoneware body... 

Handle are the first on the market in Europe with a combined deairing extrusion machine with a double-shaft mixer, shredder device, vacuum chamber and auger extruder... 

Why is the extrusion of ceramics using an auger such a widespread and successful technology Why is it that the auger extruder is of such interest to industry What do we know about it When will it work How does it happen that the auger, a type of well established equipment that certainly still lacks a complete scientific basis for its design, finds itself as the technology of choice in business for so many established and new products Questions such as these underlie the discussion here. 

So why is the extrusion of ceramics widespread and successful At first sight, the technical challenges seem considerable. For example, the particles used to form many well-shaped objects are frequently hard and abrasive. Sometimes the objects that are made need to be of very precise size or needing good mechanical or electrical properties specific to an application. The key to turning an abrasive material into a mouldable one that can be readily shaped by an auger extruder lies in the presence of, or addition of, a compound such as a clay. For some applications this compound is present naturally. Most other materials, including most synthetic ones, need to have added a clay or other additive to turn the material into one that can be moulded. 

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