The Physics of Tablet Compression: IV. Relationship of Ejection, and Upper and Lower Punch Forces during Compressional Process: Application of Measurements to Comparison of Tablet Lubricants

Abstract

The relationship of the upper and lower punch forces and the ejection force during the process of tablet compression has been studied. Large differences may exist between the maximum force exerted by the upper punch and the maximum force obtained at the lower punch. When such differences exist, substantial forces are needed to eject tablets from the die. The magnitude of the difference between the maximum upper and lower punch force and the magnitude of the ejection force appear to be linearly dependent on the area of the tablet in contact with the die wall. The value of the ejection force and the difference between the upper and lower punch forces are both markedly affected b the presence of lubricants. With a well-lubricated granulation the force exerted by the upper punch is essentially the same as that transmitted to the lower punch and a negligible force is required to eject the tablets from the die. A quantitative method for evaluating lubricants on the basis of these observations is suggested.