Tsukigata feeding system
Tsukigata feeding is usually used on low-medium speed rotary tablet press like ZP-9 and other ZP machines. The Tsukigata feeder is fixed on the turntable with a certain clearance(0.05～0.1mm). When the middle dies successively run right below the feeder, the particles in the feeder will fall into die hole. Several separated areas on the feeder make it possible to fill powder continuously and repeated. The small scrapper on the end of feeder tightly closed to the turret will scrape off excessive materials so as to make tight but even pills.
This feeding model is dependent on the gravity of material particles to complete filling process, so high requirement on the materials(uniform size and good fluidity) is required. Repeated filling pattern makes the pills uniform with little weight variation. Two-sided pressure from upper and lower punch evenly compact the pills. In particular, double pressing rotary tablet presses is attached with 2 sets of filling system. Every station of tablet tooling will make 2 pills in every rotation of turret. Such kind of machine is, therefore, suitable for bulk production(eg. ZP-35D double-press rotary pill press can produce 2000 almost pieces pills per minute.)
Defects of Tsukigata feeding system come from 2 aspects.
Strict requirement on materials. Good fluidity, uniform size and other requirements increasing production cost.
‚ Particles filling needs enough time, which limits the turret speed. Too fast rotation of turret will possibly give rise to great weight variation, insufficient filling, etc.
★ Forced feeding system
Forced feeding system is optionally applied to high speed rotary tablet press machine, composed of hopper, motor, and forced filling feeder. Hopper is used for depositing materials, joint with the forced filling feeder. Motor creates power for filling. And the feeder was divided into gear case and feeder. Gear case transmit the power created by motor to the two impellers of feeder that spin to force materials into middle die.
Particles or powders can be pressed into pills through filling, scrapping, tabletting, and ejecting four processes. As materials are forced to fall into dies, filling time can be largely shortened, and turret speed is upgraded to 80r every minute.
Though it attracts customers with a lot of advantages, disadvantages should slao be taken into consideration:
As turret speed is increased, more powders coming from the hopper are flying away, causing a waist of materials and cross-contamination.
‚ Some materials with poor fluidity are difficult to flow from hopper. But fast pressing process continues, the weight of pills can not be well controlled.
Merits and demerits can be generalized as following table:
|Feeding system||Bucket feeder||Tsukigata feeding||Forced feeding|
|Applied machine||Single punch pill press||Low-medium speed rotary machine||High speed rotary tablet machine|
|Falling Way of material||By gravity||By gravity||Forced|
|Materials||Particles||Particles||Powders or particles|