Tablets are made by compressing a formulation containing a drug or drugs with or without excipients on stamping machine called presses.
Tablet presses are designed including following basic components:
· Hopper for holding and feeding granules.
· Dies that define the size and shape of the tablet.
· Punches for compressing the granules within the dies.
· Cam tracks for guiding the movement of the punches.
· A feeding mechanism for moving granules from hopper into the dies
Tablets presses are classified either single punch or multi-station rotary presses.
In the case of single punch machines, all of the compression is applied by the upper punch while lower punch acts as a supporter, making the single punch machine a “stamping press”.
1. Single punch tablet press is also called as an eccentric press or single station press.
2. It is the simplest machine for tablet manufacturing.
3. Single station tablet press employs a single tooling station that is a die and a pair punches (upper and lower punch).
4. This tablet press is available as both manually operated and power driven.
5. In this single punch tablet press, the compaction force on the fill material is exerted by only the upper punch while the lower punch is immovable such as action equivalent to hammering motion.
6. The tablet press contains fallowing compartments,
7. HOPPER: HopPer may be one or more in number which serves two purposes 1.Firstly to hold granulated feed 2. Secondly to pass it to the feed frame.
8. For subsequent compressing the hopper can be filled manually or by using mechanical equipment.
9. FEEDING MECHANISM: The feeding mechanism helps in the guiding granulated feed from the hopper into the die cavities.
10. In the single punch, a feed shoe which is connected to the hopper is laid down on die table.
11. Tooling set: The basic mechanical and functional unit of tablet presses is the tooling set which comprises of the die cavity and a pair of upper and lower punches.
1. The tooling set comprises a pair of upper and lower and a die cavity which is also called as a station.
2. Tooling sets are available in various shapes in following sizes,
3. Dies that define the size and shape of the tablet.
4. Punches for compressing the granules within the die.
5. Cam track guides the position of the punches there connected to the head of the punches.
6. The mechanism involved in tablet press is that the compaction of powder blend is accomplished by exerting the pressure via upper and lower punches, the resultant tablets are formed in the die cavity.
7. Working process can be divided into three stages,
· Filling: The lower punch falls in the die leaving a cavity into which granules flows under the influence a gravity from the hopper.
· Compression: The upper punch, drops, and its tip enters the die.
· The porosity of the contents of the dies progressively reduced, and the particles are forced into the over closer proximity to each other.
· Ejection: The upper punch is withdrawn from the die, lower punch rises upwards simultaneously feed shoe comes over die and moves the compressed tablet from the site.
· Cycle continues.