Rotary tablet press is a mechanical device that unlike the single punch tablet press has several tooling station which rotates to compress granules/powder mixture into tablets of uniform size, shape (depending on the punch design) and uniform weight. It was developed to increase the output of tablets.
In this article, I am going to briefly describe the working principle of the rotary tablet press machine. About the analysis concerning its working principle, it will be divided into three main processes:
- Powder filling.
- Tablet Discharge.
Powder Metering Process
Tableting process involves precise filling and compression of powder in the die cavity. Therefore, the machine should move excess powder that may be the source of any form of inconsistencies. At this stage, your rotary tablet press machine should ensure the accurate filling of the die cavities. This should include the desired volume and weight of powder that should be compressed into tablets. During this process, the lower cam of the turret moves upwards to a predetermined level. This results in excess powder that is scraped from the die surface.
Tablet Compression Process
The production capacity depends on the size of rotary tablet press machine’s turret. Normally, the upper and lower punches exert a predetermined amount of pressure that compresses tablets to the right size and depth. The pre-compression process removes any traces of air that might be within the powder particles. From the pre-compression stage, it then moves to the main compression. The main compressor exerts significant amount of force that compacts powder to a desired thickness and hardness. This is due to the pressure that is exerted on the punches by a series of pressure rolls. A complete revolution should produce the exact number of tablets as the number of punch tools on the turret.
At this stage, the upper cams will pull the top punches back to their initial position. On the other hand, the lower punches are lifted up. As a result, the lower punch pushes the already processed tablets out of the die cavity. The scraper will then remove the tablet from the compression machine to the discharge chute. Basically, this will mark the end of one complete cycle of the tablet compression machine.