Tablet weight variation refers to inconsistent tablet weight or mass across samples taken from a single production batch. It is one of the most important quality control parameters in pharmaceutical manufacturing, as it directly ensures that each tablet contains the correct dosage of active pharmaceutical ingredients. Regulators such as the MHRA, EMA and the FDA require manufacturers to demonstrate that weight variation is within defined limits, typically assessed by accurately weighing a sample of tablets from each batch at regular intervals during production. Failure to control weight variation can lead to underdosed or overdosed tablets, presenting safety risks for patients and causing compliance issues for manufacturers, including the risk of needing to recall products. 

There are several common causes of tablet weight variation and addressing them requires both technical expertise and robust maintenance practices. One of the most frequent contributors to weight inconsistency is excessive variation in the working lengths of punches. When punch working lengths are non-uniform, the volume of granule compressed in each die cavity can vary, leading to tablets with different weights. To avoid this, manufacturers should validate the working length of all new or unused punches before use. Additionally, the working lengths of used tooling should be measured regularly, and any punch found to be outside the acceptable tolerance range should be reworked or replaced. A solid maintenance process that includes rigorous assessment of tools offers reliable and repeatable procedures for length measurement and punch maintenance.