Extrusion installation

In designing the accessories and choosing an injection and extrusion installation for low-pressure moulding1, it is important to evaluate the design procedure for determining the channel resistance to non-Newtonian liquid flow. Practically simple and convenient design procedures for pressure losses and hydraulic resistance of non-round channels for power liquids and liquids described by the three-parameter model may be found, e.g. in 68,69). 

The experiments used an industrial extruder ATL-45. The extrusion installation included a forming unit composed of a forming head to produce a square section 45 x 45 mm. Ultrasonic oscillations were produced in the forming head by two standard magnetostrictive transducers PMC-6-2 ultrasonic USF-1-4 oscillations. 

Fig. 37 shows a typical large extrusion installation, with multiple guns. Such equipments are used on automotive production lines, where several operators may apply adhesives or sealants in several places along the production line. 

Figure 37 (a) Extrusion installation with several guns and duel pump for high flow rate. Source Kremlin, France, (b) Apphcation of the adhesive by injection between the two parts to be bonded (sometimes used in aircraft construction). 

After this, the obtained suspension was processed in a homoge-nizer (Emulsiflex-C5, Avestin Inc., Ottawa) operated at a pressure at the homogenization valve of 300 kPa. The particle size was 230 nm after a homogenization period of 30 minutes. The final process step was extrusion using polycarbonate membrane Alters with a pore size of 100 nm installed in the... 

It is imperative that the processor utilize every advantage available to ensure success since the specification of equipment in an extrusion line also affects resin usage and labor. Thus, it is always more cost effective in the long run to design and install an extrusion line that (1) has a maximum rate capability of at least 25% more than the expected maximum rate, and (2) has a properly engineered line (that might have a higher capital cost) to achieve maximum profitability. 

It has been suggested by producers of brominated flame retardants that the health risks related to the extrusion of plastics containing PBB and PBDE could be avoided by strengthened worker protection measures In the recycling installations. As an example It was recommended that workers carry protection masks. Clearly, the substitution of the concerned substances would provide the best protection of the concerned workers." European Parliament and Council, 2002. 

Foamed PP is a new alternative material for processors of PP or PS thermoformed items for packaging applications. The joint R D programme of Italproducts, Reedy International and PP resin suppliers has made it possible for everybody involved in the packaging industry to install and run an extrusion and thermoforming line capable of producing medium density EPP items. The features of the equipment required are described. ITALPRODUCTS SRL REEDY INTERNATIONAL CORP. 

Fig. 8. Design of angular circular extrusion head with rotating core for manufacturing of tubes and hoses 1 — Single-screw extruder 2 — Adapter 3 — Core holder 4 — Separable core tip 5 — Alignment bolts 6 — Rotating core 7 — Plain bearing 8 — Stop flanging 9 — Head casing 10 — Electric heaters 11 — Place for installation of thermocouples...

The complete equipment usually consists of a mixer such as a Banbury mixer followed by the heated rolls, chilled rolls, and finally a windup roll.3 The windup roll controls the tension on the film or sheeting as it moves through the calender rolls. Calenders are generally designed to meet the specific needs of the customer. Once installed and operating continuously, the cost per pound of film or sheet is lower than by any other process such as extrusion. 

Extrusion-expelling technology is also being used in Russia, Latvia, Lithuania, and other newly independent states for extruding and expelling sunflower seed. The oil is being used for human consumption and meal for animal feed. Similar installations have been buUt to process rapeseed and peanuts (49). Table 6 shows the quality characteristics of soybean meals recovered in commercial practices by different oU-extraction processes. 

At the production lines for rubber profile extrusion as installed at the industrial partners site, most process values were already available from automatic control. Yet, these values were only available for direct display, but not recorded in any way. This is partially due to the fact that production lines in this domain usually run without major changes for several decades. Some important process values, e.g., the power consumption of the extruder engines, were not measured at all. Thus, a first important step of the project was the integration and recording of these values. Appropriate hard- and software had to be installed. Additionally, environmental conditions with possible influence on the properties of the raw materials and thus the process behavior had to be recorded, e.g., temperature, humidity and pressure. 

In Kahl flat die pellet presses, a unique feature is the hydraulic roller adjustment device. As depicted in Fig. 8.61, the roller assembly can slide up and down the main shaft and is supported by strong springs. A so called hydraulic nut , a hydraulic cylinder arrangement, with which the rollers can be pushed down or lifted, is installed at the end of the shaft. This allows to adjust the clearance or gap between the rollers and the die to optimize densification and extrusion characteristics for different materials and to modify the thickness of the predensified layer after the extrusion step. Since adjustments can be made anytime, even during operation, it is possible to optimize press performance as needed. 

Another modular system is often called laboratory equipment it can be used for small scale production and for the laboratory evaluation of small samples. Fig. 11.26 depicts the design and some of the accessories. In the most simple execution a hopper feeds a pair of rollers which are driven by a hand crank. The rollers can be solid and may be equipped with compacting or briquetting surfaces (see Section 8.4.3) or two perforated, geared, intermeshing pelleting rolls (see Section 8.4.2) are installed to accomplish medium pressure extrusion. In a modular fashion the rollers can be motorized, screw feeders can be added, and the rolls may be oriented vertical or horizontal or in any other direction. As shown in the photographs of Fig. 11.27 the roller frame can be totally enclosed for dust control if toxic or hazardous materials are processed. A panel includes controls and instrumentation for data display and collection. 

The above indicates that, while a feed mill may be equipped with one or more pellet mills that are selected to handle the production capacity with the most common feed type, conditioning, die design, extrusion speed, and, potentially, post-treatment must be variable. This is accomplished by controls, variable speed drives, the availability of various dies, and an adaptable flowchart with diverters (circles in Fig. 6.5-6) for different process path selections. Installation of redundant equipment helps to chose the most effective system and maintaining production during machine modifications and maintenance. 

Fig. 6.4-34 Sketch of the principle of smooth roll formers for the extrusion of pressure sensitive or aerated masses (courtesy Hosokawa Bepex, Leingarten, Germany) Fig. 6.4-35 Shape forming a) two-roll formers installed after, for example, a rotary bar roller press b) the roll surface carries molds that correspond to the product shape (courtesy Hosokawa Bepex, Leingarten,...

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