Tablets are probably the most common pharmaceutical dosage form and they may vary in size, shape, colour and coating.
There are four stages in the compression cycle but they occur so quickly it is not possible for the human eye to pick them up. These are filling, metering, compression and ejection. A tablet machine makes tablets by trapping specially-formulated powder into a cavity and then compressing it.
This machine is a 37-station, double-sided tablet press having two compression stages, two hoppers each feeding a separate feed-frame and therefore, in every revolution, it can produce twice as many tablets as the number of punches (2Χ37=74). The revolutions per minute (RPM) and therefore the number of tablets produced per hour, was controlled by the operator via the electronic panel at the front part of the machine.
It has variable upper punch penetration which allows compression to occur at various depths inside the die. It is also fitted with a slotted turret where each punch cavity has a slot on the side and can accommodate slotted punches which are necessary for the production of any other shape except round. This feature prevents the punches from rotating in the cavity and therefore ensures that the punches always go into the die the right way round avoiding a catastrophic rotation which would result in the punches crashing on impact.
A double-sided tablet press in operation in the 1990s. The machine was fed by the pneumatic conveying equipment that was mounted at the top and transferred the powder from the stainless-steel semi-conical container on the left-hand side of the picture. The tablets would fall into tablet de-dusters positioned at the exit chutes on each side of the machine to remove any excess dust before being collected in stainless-steel containers at the front of the machine.
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