| Tech Tip For Coating: Aiming The Spray Pattern Into The Rotating Tablet Bed |
Aiming the spray pattern correctly is a very important part of the overall Gun Geometry phase of setting up a coating
pan. If you aim the guns too high onto the bed some or even most of the coating solution may be drawn directly over the
bed without coating the main portion of the tablet body. Aiming the guns too low and you risk having the surface too wet
as it folds under the main bed on its way back. For if you look closely you can see that the rotating bed of tablets is like
a waterfall and with many potential gun positions it is possible to make a mistake. In this photograph we see a set of
guns that is probably aimed too low in the bed:
Aim the guns for the “bottom of the waterfall” Why such a non technical term for a technical process? Well because a
tablet bed is not standardized. Beds will take different appearances due to differences in tablet size, tablet shape, the
compressing yield, the number of baffles in the pan, the use of anti slide bars and so on. So there really is no set
position for all coating performed. But once you have successfully coated a new product for the first time, then you can
use some of the newer codified systems (example: the bar system provided by Thomas Engineering, USA) and
standardize the gun position description on the worksheet. In the photo below we see a more optimized gun position in
an Accela Cota 48” pan. Always aim for the “bottom of the waterfall!”.
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| Solid Dosage Training, Inc. FREE TECHNICAL HELP Coating |
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