During the loading operation, the top slider roller with punch is at the highest point of the upper caper (stage I). It then slides down the sloping kapir. The punch touches the matrix hole, plunges into it and compresses the material. The pressure builds up and reaches its maximum at the moment when the slider roller is under the pressure of the roll (pressing operation – stage II). After that, the roller with the punch starts to climb up the capir and reaches the maximum. The lower slider makes the following movements: in the loading stage, its roller is supported by the roller that regulates the volume of the matrix hole. The lower slider moves along the straight capir. During the pressing operation, its roller is lifted by the pressing roller, so that the lower punch exerts pressure on the tablet material from its side. The capir then moves slightly upward, causing the lower punch to push the tablet out (ejection operation – stage III).
After that, due to the lowering of the capir, the lower punch also goes downwards and everything is repeated again. Below is a description of the features of domestic rotary tablet machines. In general, RTMs can have from 12 to 55 dies (positions) in the rotor. Besides, they can be single-flow (with one feeding hopper) and double-flow (with two feeding hoppers). In the latter case, the entire production process is completed in half a rotation of the rotor and, as a result, the productivity of the PTM is dramatically increased. Such a high-performance machine is, in particular, RTM-41, which is a dual-flow machine with 41 pairs of press tools. This machine allows to produce tablets of 5-15 mm and 20 mm diameter. The RTM-300M machine is used to produce cylindrical-shaped tablets of small diameters with flat and spherical ends. Since in RTM the pressure is bilateral and increases (is removed) gradually, tablets are of high quality. These machines work evenly and do not dust. An agitator can be installed in the feed hopper. The rotating rotor allows the installation of devices for powdering the matrix hole before loading, as well as after it (to pollinate the surface of the filled matrix). Some designs have brush wiping or cleaning devices to keep the punches clean. Rotary press-automatic machines are produced, equipped with a vibrating feeder, which can, by adjusting the amplitude and frequency of vibrations of the vibrating, filling part of the feeder, break the forces of adhesion between powder particles, thus significantly increasing its mobility and compensating for the lack of bulkiness.

The productivity of automatic machines equipped with a vibrating feeder is increased. In this case, granulation is also required, but with slightly reduced requirements for granulate homogeneity. In domestic tablet presses, the tablet mass and possible mechanical inclusions are controlled during the tabletting process. For mass control there are automatic devices – in case of deviation of tablet mass from the preset one a signal lamp is switched on. Automatic control for metal inclusions is performed with the help of a device that detects and removes tablets with metal inclusions from the’flow. To remove from the surface of tablets coming out of the press, dust fractions are used dedusters. Tablets pass through a rotating perforated drum and are cleaned of dust, which is sucked out of the dedusters by special devices. Tableting of drugs usually occurs at pressures of 25-250 mPa; higher pressures are rarely used. Table 4.8 gives an example of the main technical parameters of rotary tabletting machines. Although RTMs are technically far superior to eccentric machines, they have some disadvantages, namely: complex construction; require more spare punches and dies. The quality of tablets is influenced by the amount of pressure, pressing speed, condition and wear resistance of the press tool, which is subjected to quite a lot of wear and tear, as it experiences heavy loads. The durability of dies is 2-3 times less than that of punches, which is explained by chemical interaction of the matrix material with the tablet mass, rigid loading of the matrix, friction of particles of the pressed material and the tablet against the walls of the matrix;
more difficult preparation for pressing; more labor-intensive cleaning; large variation in mass deviation from the nominal value due to the use of dozens of sets of press tools. Eccentric machines use only one set of press tools and therefore the variation in the mass of individual tablets is less than when pressing on RTM. Based on the above disadvantages it can be concluded that rotary tablet machines are cost-effective only for mass production. Before pressing, any tablet machine must be set up, calibrated and adjusted optimally. Before starting the process, a test tabletting process is carried out by starting the machine manually, which results in the required tablet weight, proper strength and disintegration as well as the elimination of external imperfections.