Feeder force

Crammer-feeder (force feeder) n. A device fitted to the inlet port of an extruder that precompacts a low-density feedstock and propels it into the feed section of the extruder screw. As originally produced by Prodex Corp (now a division of HPM), the crammer-feeder consisted of a conical shell within which turned a decreasing-diameter screw driven independently of the extruder. 

For fine powders that tend to bridge or stick and are of low bulk density, some form of forced feed, such as the tapered screw feeder shown in Figure 9, must be used to deaerate, precompact, and pressurize the feed into the nip. Large machines are available with up to five screw feeders to spread the flow across the roUs, and vacuum hoppers are also used to remove air when densifying low density feeds. 

Although there are laboratory tests that one can perform to quantitate the flow of a fmal lubricated granulation, such as angle of repose and flow time through a funnel 7], they are best used as comparison techniques to choose between two or more formulations. If one considers the many different tablet presses available, the use of force feeders on most modem presses, and the fine-... 

It is the authors experience that with a formulation compressed without a forced feeder in R D, the scale-up in a different country, but by gravity feed and without a forced feeder, was perfect. In a second country, however, all production presses operated with forced feeders, and the target tablet hardness was not achieved. It was possible to conclude that press speed was not the cause of the problem but it was much later (and based on laboratory experiments) that it was possible to conclude that the lubricant was ovennixed on the tablet press, resulting in a softer tablet. Fortunately, the drug was very soluble and no dissolution problem resulted, but slower dissolution could be a problem with a drug of low solubility. 

Tablet weight uniformity will provide a measure of the efficiency of the powder flow, tlie force feeder, or the automated weight control system. Weight monitoring by the press operator is usually the weight of a 5- or 10-tablet sample. Uniformity of individual tablets, which after all does relate to dose, will be more informative. The powder flow may not be sufficiently good, even with forced feeders.

Model Roll dia./mm Max. roll Position of width/mm rolls/feeder Max. force/ metric tons Overload system Approx. capacity/ kg 1 Feeder type Press drive/ kW Feeder drive / kW Roll shapes Max. feed temp./ °C... 

Schwartz [23] suggests special consideration for the compression process. Press speed for material that compact by plastic deformation, overmixing of lubricant in the force feeder, heat buildup on long compressions runs, material abrasiveness, and tooling care are important variables for consideration. Dwell time and compression and ejection forces are other variables identiLed for monitoring process. 

Compression speed The formulation should be compressed at a wide range of compression speeds to determine the operating range of the compressor. The adequacy of the material s flow into the dies will be determined by examining the tablet weights. Is a force feeder required to ensure that sufficient material is fed into the dies Compression/ejection force The compression profile for the tablet formulation will need to be determined to establish the optimal compression force to obtain the desired tablet hardness. The particle size/size distribution or level of lubricant may need to be adjusted in order to have a robust process on a high-speed compressor. 

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