Question

During compression of tablets, dwell time is:

• A. Time it takes for the punches to punch tablet
• B. Time it takes for the punches to stop moving vertically and to achieve maximum penetration in the die under the primary compression rollers
• C. Time it takes for the punches to eject the tablets
• D. Time it takes for the punches to eject tablet under the primary compression rollers

Answer 1

The Correct Option is B

The correct option is (B): Time it takes for the punches to stop moving vertically and to achieve maximum penetration in the die under the primary compression rollers.

Answer 2

The question asks for the precise meaning of dwell time during tablet compression on a rotary press. Let's check each description against what actually happens at each stage of the punch cycle.

1. Time it takes for the punches to punch tablet: This phrase is too broad to describe dwell time on its own, since it covers the whole compression stroke rather than the specific moment the punch stays at its deepest point in the die.
2. Time it takes for the punches to stop moving vertically and to achieve maximum penetration in the die under the primary compression rollers: This describes the exact moment the punch head is flattened between the compression roller and the punch, holding still at maximum penetration into the die. This brief pause is precisely when the compaction force is transmitted to the powder bed, which is the definition of dwell time.
3. Time it takes for the punches to eject the tablets: Ejecting the finished tablet from the die happens after compression is complete and belongs to the ejection phase of the cycle, a separate stage from dwell time.
4. Time it takes for the punches to eject tablet under the primary compression rollers: This again describes ejection rather than dwell, and it additionally places ejection under the compression rollers, which is not correct, since ejection happens later, away from the compression rollers, at the ejection cam.

Dwell time refers specifically to the pause at maximum die penetration under the compression rollers, not to the punching action broadly or to ejection.

The correct answer is Time it takes for the punches to stop moving vertically and to achieve maximum penetration in the die under the primary compression rollers.