What is Dwell Time:
Dwell time means the time the tablet is pressed under full force during making. When powders are squeezed into a tablet, the punches (top and bottom parts of the machine) come together and press hard. Dwell time is how long they stay pressing at the hardest point. If the dwell time is too short, the tablet might not form properly and could break or fall apart. If it is the right amount, the tablet will be strong and even. Controlling dwell time helps make sure every tablet is good quality and safe for people to use.
The Dwell Time Calculator built by LFA is designed to help you work out how long your tablet is under maximum compression. Understanding this will help you scale up from small scale R&D to batch production of your tablets.
The dwell time is calculated in the following way:
Where:
rpm = revolutions per minute (turret speed)
dt = dwell time (milliseconds)
Dhf = head flat diameter (millimeters)
Dpc = pitch circle diameter of turret (millimeters)
Benefit of Dwell Time:
- The dwell time calculation helps to understand how long your tablet is under maximum compression.
- Less Dwell Time may cause Softning, Cracking or breakage of tablet layer.
- High Dwell Time may cause high hardness or increase the disintegration time.
Factors Impacting on Dwell Time:
- The head flat diameter of the punch directly impacts dwell time. The extended surface area of the head punch leads to an increase in the dwell time, and it’s suitable for large-sized tablets. A short, flat head punch leads to a decrease in the dwell time, and production speed also increases.
- The pitch circular diameter of the turret is indirectly proportional to dwell time. A higher diameter of the turret can decrease the dwell time, and a lower diameter of the turret can lead to an increase in the dwell time.
- High speed of the machine decreases the dwell time, and low speed of the machine increases the dwell time.
You Can Also Read:
Machine Capacity Calculation in Pharmaceutical Industry
Batch Yield Calculation in Pharmaceutical Production