Quantifying the impact of press deformation on compression kinematics during tableting: An experimentally validated analytical approach

Compression speed is a critical parameter for the manufacturing of pharmaceutical tablets. Tableting scale-up often significantly increases compression speeds, frequently resulting in different final tablet characteristics or defects like capping or lamination. For this reason, compaction simulators are widely utilized to emulate the punch displacement cycles of production-scale rotary presses. While conventional simulator cycles rely on theoretical equations derived strictly from the geometric features of rotary equipment, they neglect structural frame compliance, which considerably alters the true velocity profile during tableting. The present work introduces a novel, universally applicable analytical methodology to calculate the actual, deformation-compensated compression speed by accounting for the deformation of the press and the compressibility of the tablet formulation. The method was experimentally validated against empirical punch kinematics during the loading phase on an instrumented compaction simulator. The model was then applied to a production-scale rotary press, quantitatively demonstrating that structural machine deformation reduces the actual compression velocity to nearly half of the theoretical value near peak force. The proposed method relies entirely on data readily determined in standard development and manufacturing environments, providing a highly practical tool for aligning compaction simulator profiles with production equipment, optimizing process scale-up, and troubleshooting compression speed-related production challenges.