Tablet Compression Process

Following the completion of granulation and blending, the granules are transferred to the compression stage. Prior to batch start-up, line clearance is performed and documented to verify that the compression room, tablet press, tablet deduster, metal detector, lifter, dust extraction system, and all auxiliary equipment are clean, assembled, identified with the correct equipment status labels, and ready for operation. The production area is verified to be free from product residues, labels, tooling, components, and documents from the previous batch, ensuring complete product segregation and preventing cross-contamination.

The approved Batch Manufacturing Record (BMR), Standard Operating Procedures (SOPs), equipment logbooks, cleaning records, calibration status, and production order are reviewed before compression begins. The correct D-Tooling, including the upper punches, lower punches, dies, punch tips, punch heads, punch barrels, punch keys, die bores, and die tables, are selected according to the product specification and inspected for wear, corrosion, scratches, sticking marks, deformation, excessive clearance, or mechanical damage. The tooling is installed on the rotary tablet press, followed by verification of the compression rollers, cam tracks, fill cam, ejection cam, take-off blade, force feeder, feed frame, hopper, turret, safety guards, interlock systems, and Human-Machine Interface (HMI).

The lubricated granules are transferred from the Intermediate Bulk Container (IBC) into the compression room using a lifter. After correct positioning and alignment above the machine hopper, the IBC butterfly valve is opened, allowing the granules to flow into the hopper by gravity. Throughout the transfer operation, operators monitor powder flowability, bulk density, bridging, rat-holing, segregation, powder level, and feeder performance to ensure continuous and uniform material feeding without interruption.

Inside the tablet press, the granules are conveyed from the hopper to the feed frame, where the force feeder paddles distribute the material uniformly across the rotating turret. During each turret revolution, the die cavities are filled with granules, and the powder volume is controlled by the fill cam and fill depth. Excess powder is removed during the metering stage, ensuring accurate die fill and minimizing tablet weight variation before the compression cycle begins.

Each compression cycle consists of die filling, metering, pre-compression, main compression, decompression, tablet ejection, and tablet take-off. During pre-compression, entrapped air is expelled from the powder bed, improving compact formation and reducing the risk of capping, lamination, and internal voids. During main compression, the upper and lower punches apply the specified compression force while the dwell time under the main compression rollers determines the consolidation of the powder into tablets with the required hardness, tensile strength, thickness, diameter, friability, disintegration time, and dissolution performance.

The critical process parameters (CPPs) include turret speed, feeder speed, fill depth, tablet weight control, pre-compression force, main compression force, compression force profile, dwell time, ejection force, tablet take-off position, machine output, and tablet rejection rate. These parameters are continuously monitored through the HMI and adjusted whenever necessary to maintain process capability, compression stability, and batch consistency.

Following ejection, tablets are removed from the die table by the take-off blade and transferred through the tablet deduster, where loose powder and adhering dust are eliminated by vibration and dedusting airflow. The dedusted tablets subsequently pass through an in-line metal detector, which automatically rejects tablets contaminated with ferrous, non-ferrous, or stainless-steel particles. Accepted tablets are discharged into a designated stainless-steel container, mobile bin, or directly transferred to the film coating process.

Throughout compression, In-Process Controls (IPC) are performed according to the approved sampling plan. Production personnel evaluate average tablet weight, weight variation, tablet thickness, tablet diameter, tablet hardness, friability, disintegration time, appearance, tablet temperature, compression force trend, and machine performance trend. Results are compared against the established acceptance criteria, alert limits, and action limits, and are immediately documented in the BMR to ensure complete data integrity and traceability.

Operators continuously monitor for compression defects, including capping, lamination, sticking, picking, binding, chipping, cracking, mottling, double impression, black specks, weight variation, hard tablets, soft tablets, high friability, punch seizure, die blockage, powder leakage, abnormal vibration, abnormal machine noise, high ejection force, and unstable compression force trends. When abnormalities occur, troubleshooting includes evaluation of tooling condition, granule flowability, particle size distribution, moisture content, lubricant distribution, machine settings, environmental conditions, and equipment performance before implementing appropriate machine adjustments or tooling replacement.

Upon completion of the batch, material reconciliation is performed by comparing the theoretical yield with the quantities of acceptable tablets, rejected tablets, IPC samples, dust loss, residual granules, and recoverable product. Following reconciliation, all product-contact parts are dismantled, cleaned according to the validated cleaning procedure, visually inspected, reassembled or stored appropriately, and documented in the equipment logbook. All production documentation, IPC records, deviation reports, CAPA records, and reconciliation records are reviewed to ensure completeness, accuracy, GMP compliance, and full batch traceability before release of the compressed tablets to the subsequent film coating or packaging operation.