In addition, the ellipsoidal shaped coating machine create optimal rotational movements of the drained tablets, accelerating and improving the coating conditions.
The draining machine rotates in a clockwise direction around an axis located at an inclination (vertical and horizontal mixing) to achieve good mixing. The diameter of the coating, most often made of copper, ranges from 0.7 to 1.5 meters.
The angle of inclination of the coating to the horizontal is 30°-45°, the optimum loading is 25-30 % of the coating volume. Optimum speed of rotation of the coating machine is 20-40 rpm, the number of revolutions are selected depending on the course of the technological process. Stages of the technological process of dragging tablets are as follows: enveloping, or priming; layering, or rolling, – the most important stage, as it is here is mainly the formation of the entire shell; smoothing, or polishing; glossing – the last stage of dragging, at which the tablets are given luster, marketable appearance.
Prof. PD. Pashnev in 1975 developed a new method of coating tablets – suspension method of dragees, the dispersion medium in which is 70% sugar syrup. Polyvinylpyrrolidone (PVP) as a plasticizer, magnesium carbonate as a filler, titanium dioxide as a dye and aerosil to stabilize the suspension.
PVP is a high molecular weight compound, the molecules of which, attaching to each other, form a spatial grid in solution. Sugar molecules dissolved in water are enclosed in the grid cells.

In the process of drying the processed tablets, the water in the individual cells is removed. The sugar remaining in the cells, crystallizing, does not have the ability to combine into agglomerates. Fine crystals with low brittleness and high plasticity are formed [2, 3]. BASF suggests the use of Collidon 25 and Collidon 30 in sugar dredging (see section 4.9). The physical characteristics of these substances, such as prevention of microcracking, adhesion of the sugar layer to the tablet core, uniform distribution of dye over the tablet coating, slower and more homogeneous crystallization of the sugar, favor the coating process and improve the quality of the coatings. Sugar coatings are particularly susceptible to cracking when applied to large batches of tablet cores that dry quickly. Since most medecine substances are hydrophobic, Collidon 25 and Collidon 30 are used as additives to prevent cracking-induced peeling of the tablet coating from the tablet core during manufacturing. Table 4.9 shows an example of a slurry composition for automatic sugar coating. The data are shown for 40 kg of 420 mg tablet nuclei in a conventional coating tank when 25 kg of the above-described slurry is atomized under the following conditions: duration of the atomization step – 5 s; interval – 10 min; hot air drying time – 10 min; total coating time -16 hr. A more modern way of sugar dredging process is offered by Glatt company, which uses for this purpose new generation drum machines.