Pressure roll

It follows from the relation obtained that the minimum electrically conductive additive content is directly proportional to the effective density of the additive. By "effective density" we understand the density of the material under real conditions of making the electrode (with allowance for the actual molding (rolling) pressure, humidity, temperature, etc). In this respect, TEG has unique advantages over all existing types of additives. The density of this material in free state (bulk density) is 0.05 g/cm3, which is about one-fourth of that for the ordinary graphite and one-fifteenth to one-twentieth of that for the metal powders (e.g. nickel, copper powders, etc.). 

Study determined the compact throughput, compact density, and fines (not compacted during vacuum deaeration) when using a new equipment feed system design. The parameters controlled and monitored during the compaction process were vacuum deaeration pressure, roll pressure, roll and screw speeds, room temperature, and humidity. 

Note Compactor parameters roll pressure = 62-65 bar, roll speed = 8rpm, horizontal screw feed = 52 rpm, de-aeration = —0.2 bar, sized by double rotary granulators 4 mm and 1.2 mm screens. 

Trial no. Vacuum deaeration (15 in. Hg) Roll pressure (kN) Roll speed (rpm) Screw speed (rpm) Compact density (g/cm ) Compact rate (g/min) Fines not compacted (%)... 

Different spectral preprocessing and transformations available in SIMCA P-p (version 10.0, Umetrics, Sweden) were evaluated and the best approach for data handling and manipulation was determined. Data collected on the surrogate tablets were divided into a training set to generate the PLS models, and prediction set to test the PLS models. MCC powder, equilibrated at different RH, was also roller compacted at different roll speeds on a Fitzpatrick IR220 roller compactor fitted with smooth rolls. Powder feed rate and roll pressure were kept constant for all experiments. The key sample attributes measured on the surrogate tablets were also measured for the samples prepared by roller compaction. 

The 10% w/w APAP powder blend was roller compacted. Different moisture contents were achieved by equilibrating and roller compacting the above powder blend under 24, 45, and 65% RH conditions, representing 3.3, 5.0, and 6.3% w/w moisture content, respectively. Compacts were prepared at 5.0, 6.0, and 7.2 rpm roll speeds with the powder feed rate and roll pressure kept constant. Compaction run time was four minutes at each roll speed. Samples were also collected for off-line measurements of... 

Figure 6.22 depicts schematically the flow configuration. Two identical rolls of radii R rotate in opposite directions with frequency of rotation N. The minimum gap between the rolls is 2H0. We assume that the polymer is uniformly distributed laterally over the roll width W. At a certain axial (upstream) location x = X2 (X2 < 0), the rolls come into contact with the polymeric melt, and start biting onto it. At a certain axial (downstream) location x A), the polymeric melt detaches itself from one of the rolls. Pressure, which is assumed to be atmospheric at X2, rises with x and reaches a maximum upstream of the minimum gap location (recall the foregoing discussion on the pressure profile between non-parallel plates), then drops back to atmospheric pressure at X. The pressure thus generated between the rolls creates significant separating forces on the rolls. The location of points A i and X2 depends on roll radius, gap clearance, and the total volume of polymer on the rolls in roll mills or the volumetric flow rate in calenders. 

Roll pressure Auger screw rate Roller surface type Compression profile... 

The major disadvantages of dry granulation are the reduction in tablet compressibility, formulation-dependent process optimization, and inconsistency of equipment types with respect to the process parameters being measured (e.g., roll force vs roll pressure), thus complicating transfer between equipment types. In spite of these... 

For the above reasons, processes that involve combinations of heat and pressure are the most widely used. This is normally accomplished by hot-roll pressure devices in which at least one roll is heated with a quartz lamp (Lee, 1975 Prime. 1983 Kuo. 1984 Hiraoka et al.. 1993). Offset of the toner to the fuser roll can be avoided by the use of special oils wicked onto the surface of the roll. Most roller fusing devices use heated rolls coated with silicone or fluorocarbon elastomers. Composite layer structures with multiple layers for improved process lifetime are becoming more common. Figure 17 shows a cross-section of a typical fuser roller and Fig. 18 shows a typical fusing process. For a review of fusing materials, see Gruber et al. (1989). For a discussion of the effects of paper properties on fusing, see Sanders et al. (1996). 

Certainly, a key enhancement that highlights today s pharmaceutical industry s state-of-the-art roller compactors, is programmable logic controllers (PLCs). They are used to control and monitor mechanical parts that regulate screw feed rate, roll speed, roll pressure, roll gap, vacuum deaeration, and mill speed. This section will not discuss PLC designs as it relates to compactor design features and advancements. 

The compaction rolls operate at different speeds and are supported on heavy-duty bearings in such a way that the lower roll is fixed and the upper roll is slightly movable in the vertical plane. The deaerated material passes through the roll pair, which is under infinitely variable hydraulic pressure. The deaeration, auger feed screws design and speed, roll speed, and hydraulic roll pressures are the main factors in producing a compact with specified properties. 

Miller s experiments evaluated the effects of powder density, screw feed speed, roll speed, roll pressure, vacuum deaeration pressure, compaction rate, and... 

The Fitzpatrick Co. roller compactor (Fig. 20) features two feed screws in series one horizontal and the second vertical. This system is designed to transfer powder bulk into a set of cantilevered rolls positioned in the horizontal mode one is fixed, the other floats. Operator interface allows for on-line monitoring and controlling feed screw speeds, roll pressure, and roll gap. Features such as on-line help and diagnostic functions, maintenance, and calibration screens are displayed. All functions are interfaced and adjustable by PLC for process control and report generating. The machines have vacuum deaeration and roll cooling capabilities. The sizing unit is separate from the compactor and is either a rotor bar or a hammer mill. 

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