Use of Mixer-Torque Measurements as an Aid to Optimizing Wet Granulation Process

Instrumentation designed for monitoring the wet granulation process is described. A Hobart mixer was instrumented with a slip ring torque sensor using a voltage of 5 volts D.C. to excite a strain gauge bridge. An amplifier was used to magnify the low signal levels produced by the strain gauge bridge and the gain was set at 179.6 so that 2 volts equals 200 inch ounce. The output was recorded using a Bascom-Turner recorder. The relative dynamic torque, was measured in millivolts as a function of granulating fluid added and time to optimize the granulation process using the planetary mixer. The instrumentation described in this paper has considerable potential for optimization and validation studies for wet granulation procedures.