Weight uniformity

Simulation Approach The numerical simulations were carried out using program SIMGAUSS, see data file TABLET C.dat for content uniformity, respectively TABLET W.dat for weight uniformity. The mean weights and contents were varied over a range covering the nominal values. 

The prediction power of the shear cell measurement for powder flow as judged by tablet weight uniformity is shown in Figure 2. Discrepancies, especially among powders with good flow, are observed. 

Figure 2 Shear cell index versus weight uniformity from a B3B tablet press.

Despite the diligent use of predictive studies, compaction simulation, pilot scale work, the state of the art of tablet scale-up still provide opportunities for problems to arise. The issues typically encountered are those that have multiple factors involved, and are difficult to predict and simulate at smaller scale. Of these problems, tablet mixture flow, including weight uniformity and segregation, and sticking and picking of the tablet mixture to the tools and tablet specks, are common occurrences. 

During scale-up of a bilayered tablet, it is necessary to determine the range of tamping that can be tolerated for a product. Typically, the tamping force and overall compression force are varied and the tendency to laminate is observed. In addition, the other tablet characteristics are also determined, e.g., hardness, thickness, weight uniformity, disintegration, and dissolution. 

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.

Greater weight uniformity is achieved with coarse powders or granules as feed. Too large a proportion of fines may cause the tablets to come apart upon ejection. Satisfactory feed can be prepared by first making large tablets in another machine and then... 

Appearance Hardness Tablet weight Friability Disintegration Weight uniformity... 

The systems to control weight uniformity are not able to control uniformity of the mixture. When during filling of the die the tableted material demixes, tablet weight... 

There are other factors that could contribute to weight uniformity issues. Fill-weight variation owing... 

Upper punch lowering cam The upper punches are lowered into the die cavity by the upper-punch lowering cam. This cam is typically CAD optimized to minimize the acceleration and velocity of the upper punch as it enters into the die cavity. In this way, the upper punch travels in a smooth and controlled manner as it enters the die cavity, thus improving weight uniformity. 

Dished or Conical Bottoms "Supports must be so located as to support the vessel and its extra weight uniformly and completely without distortion of the vessel. Thus ... 

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