Tablets are mainly developed on the basis of dispersions and pills, and their application has a long history. As early as in the late 10th century, there were molded tablets, and in 1872, Jonh Wyeth and others developed tablet presses, which led to the emergence of compressed tablets, which are the most widely used tablets nowadays. Since then, with the continuous progress of science and technology, the continuous development and improvement of tablet pressing machinery, the production and application of tablets have been developed rapidly, and now it has become one of the most widely used drug dosage forms in clinical application, and occupies an important position in the production of preparations in various countries in the world.
In the production of tablets, tablet press is the most critical and important equipment. There are more than 40 types of tablet presses, which can be used for the preparation of various tablets.
What Are The Different Types Of Tablet Presses
Tablet presses can be simply divided into single-punch tablet presses (single-punch tablet presses, basket presses) and multi-punch or rotary tablet presses (ordinary rotary tablet presses, sub-high-speed tablet presses, high-speed tablet presses, chip-packing tablet presses, all-powder direct tablet presses, etc.). Among them, the single punch tablet press is inexpensive, easy to operate, simple structure, and therefore widely welcomed by laboratories, research institutes and hospitals and colleges and other researchers. However, due to the many shortcomings of the single punch tablet press, sometimes the results of the laboratory trial and the actual production of rotary tablet presses obtained by the results of the difference is very large, and can not be directly copied for the practice of the production of its data. Rotary tablet presses, on the other hand, are limited in their application due to their complex structure, high price, and the need for operator training, and most of them are only used in pharmaceutical production.
Single Charge Tablet Press and Multi-Punch Tablet Press Features
| Parameter | Single Punch Press | Rotary Press |
|---|---|---|
| Pressure | Low (1.5 kN) | High (5–150 kN) |
| Pre-pressing Device | Not available | Available |
| Speed | Slow (fixed speed) | Fast (adjustable speed) |
| Overload Protection | Absent | Available |
| Material Fluidity | Non-observable | Observable |
| Compression Method | Impact force (uneven pressure distribution) | Gradual pressure (uniform distribution) |
| Compression Process | No dwell time (poor air exhaust) | Dwell time (effective air exhaust) |
| Product Quality | Average (prone to capping) | High-quality |
| Operation | Simple (open system, non-GMP compliant) | Complex (closed system, GMP compliant) |
The working principle and main structure of rotary tablet press machine
1, rotary table structure: the rotary table is the main executive part of the machine. There are upper and lower bearing components, spindle, rotary table and other major components. The main spindle is supported on the bearing, driven by worm gears and connected by splines to drive the main spindle and make the rotary table rotate.
2, track mechanism: track has upper track and lower track composed of cylindrical cams and plane cams, is the upper and lower punch rod movement track. The upper track consists of multiple tracks such as upward punching upward track, upward punching downward track, upward punching upward parallel track, upward punching downward parallel track, and pressing down road track. They are fastened to the upper track disk respectively. The lower track consists of downstroke upward track, downstroke downward track and filling track. They are installed on the lower rail seat.
3, filling adjustment device: filling adjustment is used to adjust the weight of tablets. The filling regulator is installed in the interior of the main body, and the moon shaped filling rail can be observed on the plane of the main body, which rises or falls by the action of the spiral to control the filling volume, and when the disk is turned to regulate, the filling volume decreases clockwise, and increases vice versa.
4. Thickness (pressure) adjustment device: the thickness (pressure) of the sheet is adjusted by adjusting the lower pressure wheel up and down. The lower pressure wheel is installed in the groove of the main body, which is set on the eccentric shaft, and the outer end is connected to the handwheel, when the external handwheel is adjusted, the eccentric shaft drives the pressure wheel to rise and fall, i.e., adjusting the thickness of tablets (pressure) to control the thickness and hardness of tablets, and the upper and lower adjustment of the upper and lower pressure wheels can be used as an adjusting device, but it is not adjusted under general circumstances.
5,Feeding device; the device consists of feeding hopper, adjusting screw, feeder and other parts. The feeder is a moon shaped grid feeder, which is installed on the turntable. The gap between the feeder and the working surface of the turntable and the height of the hopper are adjusted according to the fluidity of the particles.
6, transmission device: the transmission part of the machine is composed of motor, synchronous belt wheel and worm gear reducer, pilot wheel and so on. The electric motor is mounted on the motor seat of the bottom plate, and after the motor is started, the power is transmitted to the decelerating worm gear through a pair of synchronous belts. The electric speed is adjusted by AC frequency conversion stepless speed regulation. Open both sides or the back door, you can directly observe and contact with the belt these parts.
7,Hood part: the machine shell is fully enclosed, in line with GMP requirements. The upper part is surrounded by four windows for easy cleaning and maintenance. The lower half of the stainless steel door closed, in general is locked closed, only in the maintenance and installation of the mold to open the door. The front of the machine is fitted with an operator's desk. The press chamber is separated from the transmission part of the machine by a stainless steel enclosure, which ensures the cleanliness of the press chamber and protects the transmission parts from powder contamination and corrosion.
Installation adjustment and use
1,Installation and adjustment of punching mold:
1.1 Preparation work before the installation of punching mold: Remove the hopper and feeder. Open the right door, turn the handwheel to clean the working surface of the turntable, mold hole and the punch mold to be installed. Rotate the pressure adjustment closing wheel to minimize the pressure. Remove the lower punch loading and unloading rails.
1.2 the installation of the mold: turn the table in the mold fastening screws rotated out of the outer circle of the turntable 1 mm or so, pay attention to the powder suction nozzle and other parts do not touch, do not make the mold into the head of the screws when touching the appropriate. In the mold device is tight, placed in a smooth, will be punched through the bar into the upper punch hole, and then gently punched into. After the middle mold into the mold hole, its plane is not higher than the plane of the rotary table is qualified, and then the screws will be tightened.
1.3 Installation of the upper punch: firstly, remove the embedded tongue, then insert the upper punch rod into the hole, rotate the punch rod with the thumb and forefinger to check the flexibility of sliding up and down of the head into the middle mold, and no jamming phenomenon is qualified. Then rotate the handwheel to the neck of the punch rod to contact the parallel rail. After all the upper punch bars are installed, install the embedded tongue.
1.4 Installation of the lower punch: install according to the method of the upper punch, after the installation of the lower punch loading and unloading rail installed.
1.5 type running: a full set of molds installed, turn the handwheel, so that the turntable rotation 2 weeks, observe the upper and lower punching rod into the mold hole and run on the track. No jamming and collision phenomenon is qualified. To note that the highest point (i.e., out of the piece), should be 0.1 ~ 0.3 mm above the working surface of the rotary table. Close all the doors, start the motor, idle for 2 minutes, until smooth operation before use.
2, the installation and adjustment of the feeder: the feeder will be installed in the feeder support frame, and then screw the knurled screw, and then adjust the adjusting screw, so that the gap between the bottom surface of the feeder and the rotary table surface for 0.05 ~ 0.1 mm, tighten the knurled screw, and then adjust the height of the scraping board, so that the bottom plane and the rotary table working surface flush. Tighten the screws.
3, the filling amount of adjustment: filling adjustment by the right handwheel installed in front of the machine to control the adjustment of the handwheel on the side of the indication mark. When the handwheel is rotated in clockwise direction, the filling volume decreases and vice versa increases. Adjustment should be noted that there are enough particles in the filler, while adjusting the pressure so that the tablets have enough hardness for weighing.
4, tablet thickness (pressure) adjustment: tablet thickness (pressure) adjustment is controlled by the adjustment handwheel installed on the left side of the front of the machine, and there is an indication mark on the side of the handwheel. When the handwheel is rotated in the counterclockwise direction, the tablet thickness decreases (pressure increases), and vice versa the tablet thickness increases (pressure decreases). When the filling amount is adjusted, check the thickness and hardness of tablets, and then make appropriate fine-tuning until qualified.
5,Adjustment of the amount of powder delivery: when the filling amount is adjusted, adjust the amount of particles. First of all, loosen the screw on the side of the bucket frame, and then rotate the adjustment screw on the bucket frame, adjust the distance between the mouth of the hopper and the working surface of the rotary table, and its distance is generally observed in the feeding port of the accumulation of particles in the amount of storage do not overflow as qualified. After adjustment, the screw will be tightened.
6, the choice of speed: adjusting the speed method is relatively simple, as long as the rotary knob, clockwise for the speed increase, and vice versa, the speed decreases. The key is the choice of speed, the service life of the machine, the weight of the tablets, the quality of the tablets have a direct impact. Due to the nature of the particles, viscosity, moisture content, particle size distribution of particles and the size of the tablets, the pressure is different, so it can not make a uniform set, only according to the actual situation and the experience of technical personnel to determine. But in general, if the pressing of minerals, plant fiber content, large size, poor viscosity of the material, it is appropriate to use a low make pressure sheet. The highest speed generally does not exceed 25 rpm. On the contrary, if the suppression of viscosity, good fluidity, small diameter, easy to become particles, you can choose a higher speed. The speed of tablet pressing can be obtained by test pressing and adjustment. It is recommended that the speed for continuous tablet pressing not exceed 80% of the maximum rated speed.