External Lubrication of Punches and Dies - A Useful Alternative

➡️ Anhaltende Herausforderungen in der Tablettenproduktion

If sticking or overlubrication is a permanent problem during tablet production, a useful alternative can be the external lubrication of the punches and dies. It is a standard add-on for modern rotary tablet presses.

➡️ Persistent Challenges in Tablet Production

A nozzle sprays dry lubricant just before the feeder onto punches and dies. Therefore, the normal fill cam needs to be exchanged against a special fill cam, which pulls down the lower punch before the feeder. This allows also the die walls to be covered with lubricant. Spray rate and air pressure as well as the nozzle must be adapted to the needs in production. Punch size and tableting speed are important to find the right settings.

➡️ Key Benefits of External Lubrication

A lot of products can benefit from the external lubrication, for example:

- Sticky Products: For which an increase of lubricant is not possible. This might be due to:
- The negative impact of the additional lubricant on tablet strength or dissolution rate.
- Regulatory reasons preventing an increase of lubricant.

- Products Prone to Overlubrication: Products with borderline flowability often require higher paddle feeder speeds, turning the feeder into a blender. External lubrication simplifies manufacturing in such cases.

➡️ Drawbacks to Consider

Of course, there are also drawbacks to external lubrication:
- Additional equipment is needed.
- If not adjusted properly, spraying can lead to a very dusty environment.

➡️ A Targeted Solution

Nevertheless, external lubrication is a useful alternative. The lubricant is placed exactly where it should fulfil its function—on the punches and die surfaces—and not inside the product, where it is useless and only causes problems.