Why do we measure hardness of tablets?
Tablet hardness can serve as a guide for product development and as a quality-control specification. The tablets should not be too hard or too soft, as a hard tablet could prevent the dissolution of the tablet, which is needed for an accurate dosage.
How to test tablet hardness?
Compression testing and 3 point bend testing. For compression testing, the analyst generally aligns the tablet in a repeatable way, and the tablet is squeezed between a fixed and a moving jaw. The tablet hardness tester continually applied force with a spring and screw thread until the tablet started to break. When the tablet fractured, the hardness was read with a sliding scale.