Soft extrusion

Designation used in structural ceramic industry Soft extrusion Semi-stiff extrusion Stiff extrusion ... 

Conventional Combination Pressure Head and Die Assembly for Soft Extrusion of Common Bricks... 

Fig. 10 Standard combination pressure head and die assembly for soft extrusion...

Experience shows that the impact deformation heights according to Pfefferkorn for bodies to be extruded lie within a span of approx. 25 mm for soft extrusion and approx. 37 mm for stiff extrusion. 

The plasticity of the samples was measured fi om the Atterberg Limits (Plastic Limit, LP, and Liquid Limit, LL) and Plasticity Index (TP). The amount of added water in the mixer depends on the clay plasticity an on the consistency at which the extrusion is performed. The moisture content for stiff extrusion is 15-20 %, and 21-26 % for soft extrusions [36]. In the present work, FW, OW or OOW was added to 22 wt %, the results indicated that the plastic limit or amoimt of minimal water to mold the mixture decreased when using OW (19.7 %) or OWW (20,1 %) as mixing water. These results demonstrated that the volume of OW or OWW amount needed to produce the optimum extrusion performance is smaller than that the fresh water was used (21,9 %). This would be attributed to an additional lubricating effect performed by the addition of the wastes. Similar results were previously found in the extrusion effect when adding olive oil mill wastewater (OMW) [31, 32]. However, the plasticity index that establishes a range of moisture content in which the clay is moldable, decreased when FW is replaced by OW or OOW from 9.6 % to 6.1 % and 5.9% respectively. 

Extrusion Resins. Extmsion of VDC—VC copolymers is the main fabrication technique for filaments, films, rods, and tubing or pipe, and involves the same concerns for thermal degradation, streamlined flow, and noncatalytic materials of constmction as described for injection-molding resins (84,122). The plastic leaves the extmsion die in a completely amorphous condition and is maintained in this state by quenching in a water bath to about 10°C, thereby inhibiting recrystallization. In this state, the plastic is soft, weak, and pHable. If it is allowed to remain at room temperature, it hardens gradually and recrystallizes partially at a slow rate with a random crystal arrangement. Heat treatment can be used to recrystallize at controlled rates. 

Being either brittle or soft, these resins do not have the properties for moulding or extrusion compounds. These are, however, a number of properties which lead to these resins being used in large quantities. The resins are chemically inert and have good electrical insulation properties. They are compatible with a wide range of other plastics, rubbers, waxes, drying oils and bitumens and are soluble in hydrocarbons, ketones and esters. 

In Section 4.2.7 we considered the process of extrusion blow moulding which is used to produce hollow articles such as bottles. At that time it was mentioned that if molecular orientation can be introduced to the moulding then the properties are significantly improved. In recent years the process of injection blow moulding has been developed to achieve this objective. It is now very widely used for the manufacture of bottles for soft drinks. 

Thermoplastic elastomers (TPES), as the name indicates, are plastic polymers with the physical properties of rubbers. They are soft, flexible, and possess the resilience needed of rubbers. However, they are processed like thermoplastics by extrusion and injection molding. 

Ballast mats, raw material of degrading regenerated rubber The raw material of regenerated rubber Products of molding and extrusion, rubber mats, soft pipes for irrigating, vases, modihed asphalt for paving Used in renewal of tire (under 20 p.m, 30 phr)... 

Multilayer sheet extrusion, VDC copolymers in, 25 725, 734 Multilayer soft lithography, for lab-on-a-chip valves, 26 975... 

Charge Air Cooling Duct on 2004 Ford Super Duty F-Series Truck is produced from soft and hard durometer Hytrel (TPEE) grades in sequential co-extrusion process. Three plastic pieces replace seven metal pieces. 

Unicellular foams are used for insulation, buoyancy, and flotation applications, while multicellular foams are used for upholstery, carpet backing, and laminated textiles. Expanded PS (Styrofoam), which is produced by the extrusion of PS beads containing a volatile liquid, is used to produce low-density moldings such as foamed drinking cups and insulation boards. Foamed products are also produced from PVC, LDPE, urea resins, ABS, and PU. PU foams are versatile materials, which range from hard (rigid) to soft (flexible). These are produced by the reaction of a polyol and a diisocyanate. 

The major difference between injection and extrusion blow molding is the way the soft hollow tube (called a preform or parison) is made. In injection blow molding, two different molds are used. One mold forms the preform and the other mold is used in the actual blow-molding operation to give the final shaped article. In the molding process, the softened material preform, from the preform mold, is introduced into the blowing mold and blow-molded to... 

Using a melt extruder with only feed screw elements (similar to wet extruder), a dense extrudate was obtained at 20 rpm that became soft and powdery at 50 and 100 rpm (42). At a lower speed, the material resides longer within the chamber and that could lead to greater homogeneity of binding fluid (water) in the material. In addition, the slower rate of extrusion provides a more uniformly dense extrudate. 

Basic operations such as mastication, mixing, calendering and extrusion are similar for ebonite and soft rubber. The problems, especially in the compounding and vulcanization process which arise in the manufacture of ebonites, are quite different from those with soft rubbers and different tests are used for control of manufacture and for the assessment of the quality of the product. The outstanding differences between ebonites and soft rubbers are detailed below. 

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