The Different Types Of Tablet Coating Machines
Tablet coating machines work on the simple principle of applying the coating ingredients in the form of a solution to a group of tablets in a bed that may move horizontally or vertically. A concurrent flow of heated air helps to evaporate the solvent. The coating is equally distributed to the tablets through the movement of the bed.
There are several types tablet coating machines currently in the market today. The three principal types are described below.
1.Standard Coating Pan
This consists of a circular metal pan between about 15 and 200 cm (6 to 80 inches) in diameter that is tilted on a benchtop stand. The pan can be rotated with an electric motor.
A batch of tablets are loaded into the pan which is set to rotate. The rotating motion causes the tablets to tumble within the pan. Coating solution is applied to the rotating tablet bed by spraying in atomized form which can produce a faster and more even distribution than simply introducing it as a liquid.
Drying efficiency can easily be achieved by
1.an immersion sword-the drying air is distributed through a perforated metal sword that is immersed in the bed.
2.use of a baffled pan and diffuser (as marketed by Pellegrini) which allows the distribution of drying air uniformly over the surface of the tablets.
3.an immersion tube system – the tube is immersed in the bed where the tube delivers heated air through the spray nozzle.
This equipment consists of a partial or full perforated drum that rotates on its horizontal axis, the whole system being enclosed in a sealed housing. Examples are:
1.Accela-cota/Hi-coater Systems - with this equipment, the drying air is directed to the drum, passing through the tablet bed and is released through the perforations in the drum.
2.Driacoater – Similar to the Accela-cota in the Driacoater, channels for directing the supply and exhaust air the drying air are integrated into the drum wall as reinforcing elements. is introduced through a hollow area located inside the drum’s periphery. During the drying process, the drum rotates the dip into the tablet bed and dry air passes up through and fluidizes the tablet bed with the air exhausting through the back of the pan.
3.Glatt coater – this design uses fully perforated drums – a feature which combines maximum spray rates and extremely short process times. The horizontal process air flow minimises turbulence in the nozzle area and therefore also contributes to a perfect coating result. The drum geometry and the Glatt Fischer baffles mix and protect the product at the same time, guaranteeing a very even and exceptionally high-quality coating. The drum is integrated in the unique GC Smart housing, where all points are extremely easy to access; it is fully welded and the suspended drum is mounted at the rear without any front support to get in the way.
The coating solution in all of the perforated pan systems is applied through spraying nozzles which are positioned inside the drum.
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