Tablet edge thickness

The compression subsets comprise the upper roller assembly and the lower roller assembly. The upper roller assembly is located on the roof plate of the press and utilizes an adjustment system for the regulation of the insertion depth. The lower roller assembly is located on the underside of the die table and utilizes a device for the regulation of the tablet edge thickness. 

The force control systems assume a linear relationship between tablet weight and compression force for a particular granulation, tooling set, and machine tablet edge thickness (i.e., distance between compression rollers). By establishing the relationship between compression force and tablet weight at a specific machine tablet edge thickness (as shown in Fig. 8), a force... 

While in the automatic mode, the machine tablet edge thickness is increased or decreased to increase or decrease the tablet weight, respectively. For example, by increasing the machine tablet edge thickness, the measured compression force is decreased. The force control system will then increase fill depth to return the compression force to its previous value thus increasing tablet weight. 

The weight control systems that change the force control setpoint result in a change of the compression force throughout the run with a relatively constant tablet thickness. On the other hand, by changing the machine tablet edge thickness, the compression force remains relatively constant throughout the run while the tablet thickness varies. Since these adjustments are usually relatively small, both methods of machine adjustment typically produce similar results. 

Figure 10.23 (a) Coating thickness of 2D map from a nonembossed side of a tablet showing layer thickness decreasing from the center to the edges, (b) The curved dark blue line in the cross section reflects this thinning of the coat toward the edges. 

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