Using rotary tablet press punches of consistent length is critical because their length directly relates to the uniformity of the hardness, weight, and thickness of compressed tablets. If you don’t understand how length and cup depth affect tablet quality, you may attribute tablet defects to the wrong source. Thus, it is important to establish a punch inspection and maintenance program that will enable you to verify that all punch lengths and cups are within dimensional tolerances.
This paper describes how to understand punch length, how to measure it correctly, and how wear affects length and tablet consistency. It also addresses the importance of specifying cup-depth tolerances.