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Common Problems Of Tablet Pressing Machine

Feb 27, 2020

Common problems of tablet pressing machine


(1) Tablet pressing machine: a machine for pressing dry granular or powdery materials into tablets through a mould.

(2) Single punch tablet press: a tablet press with vertical reciprocating motion of a pair of dies.

(3) Rotary tablet press: a tablet press with multiple dies evenly distributed on the rotary table and vertical reciprocating motion according to a certain track.

(4) High speed rotary tablet press: rotary tablet press with the linear speed of the mould axis rotating with the turntable not less than 60m / min


There are many kinds of dies, but we can distinguish them according to different equipment, materials, standards and shapes


1.1 According to the different equipment used, there are single punch die, rotary press die, basket press die and press die;

1.2 According to different materials, there are alloy steel die, hard alloy die, ceramic die, chrome plating die and titanium plating die; the most common alloy steel materials of domestic die are: GCr15, Crl2MoV, crwumn, 9mn2v, 9CrSi; the most common materials of imported die are: A2, O1, S1, S7, PHG. S, phg-p.

1.3 According to different standards, there are ZP standard (gb12253.90) dies, IPT international standard dies, EU standard dies and various non-standard special tablet press dies and battery ring dies; (the standard of high-speed tablet press dies JB / t20080.1-2006 (T Series) recently passed the joint examination)

Because of the different standards and machine styles, there are two kinds of die for single punch and rotary press. According to the different specification, diameter and tablet shape, the stamping dies of single punch and rotary tablet press can be divided into circular punch and special punch.

Round punch: shallow arc round punch, deep arc round punch, oblique flat round punch, pure flat round punch special-shaped punch: in addition to the round geometry, such as ellipse, key shape (capsule shape), triangle and other specific needs of what kind of punch, can be customized according to the requirements of the demander.

Die model: according to the size of the punching rod, there are four types: B type, BB type, BBS type and D type; according to the adopted standards, there are four types: ISO, tsm5, tsm7, EU, GL, etc. (among them, ISO is the international standard, tsm5 and tsm7 are the North American Standard, EU is the European Union standard, GL is the national pharmaceutical Longli standard.

The odd punch is relative to the double feeding tablet press, the purpose is to avoid the co vibration of the symmetrical pressure wheel and the pressure at the same time; if it is a high-speed rotary tablet press with unilateral feeding, the odd punch and even punch are available.


The first is the packing. Generally, the packing of the single punching machine only relies on the gravity for blanking. When the material fluidity is not good, there will be filling problems. Rotary tablet press has a forced feeder, which is better than a single sheet press.

Then it is the sheet forming time. The single punch forming time is long, and the maximum hardness that can be pressed out is high. Because of the fast rotation speed and short sheet forming time of rotary tablet press, the maximum hardness that can be pressed out is not as good as that of single punch.

Then there is preloading. Many rotary tablet presses have preloading wheels, which can help to discharge the gas in the powder and particles first and prevent powder discharge, etc., which can not be achieved by single tablet press.


Nowadays, among the commonly used circular punches in China, generally speaking, the film coated tablets generally choose the shallow concave circular punches, while the sugar coated tablets generally choose the deep concave circular punches, while the flat punches are relatively less used. However, many foreign films have chosen flatting, including some film coated films and dispersive films. The difference between flat punching and shallow concave punching is not great, but the difference between flat punching and deep concave punching is large. If the material's compressibility is not very good, but it can be pressed with flat punch or shallow concave punch, it may not be pressed with deep concave punch, and it will crack. The reason may be that the difference between the edge and the middle of deep drawing is too large, which leads to uneven stress. Crispness and coating effect, the middle of the deep concave punch is too prominent, easy to wear. It will affect the crispness and coating effect.



Types and properties of excipients

The choice of excipients in direct tablet pressing is very important. In addition to the performance of general tablet excipients, the most important requirement is that excipients should have good fluidity and compressibility, as well as appropriate bulk density and large drug capacity (that is, adding more drugs without significant adverse effects on their fluidity and compressibility). The auxiliary materials commonly used for direct tablet pressing are:

Microcrystalline cellulose is a white or almost white powder, odorless, tasteless, insoluble in water, ethanol, acetone or toluene, with very good compressibility, certain fluidity and disintegration. It is a good filler and effective dry adhesive for tablets, with good hardness after being pressed into tablets, and does not affect disintegration. This variety has a large capacity for drugs, and its dosage can be from 5% to 65%. But it has hygroscopicity. Now there are products on the market in China.

Pre gelatinized starch is a white powder, odorless, tasteless, and has good fluidity. The repose angle of the national product is 36.6 degrees, with good compressibility; it has the function of lubrication, reducing the force of the tablet from the mold hole; it has good disintegration and dry adhesion, increasing the hardness of the tablet, reducing the brittleness. This product is an ideal multi-functional auxiliary material for direct powder compression, the dosage is generally 5% - 20%.


Lactose spray dried lactose is used as a supplementary material for direct compression of powder. It is white crystalline powder with no hygroscopicity. The tablets are smooth, beautiful, fast release, fluidity, and good adhesion. It is an ideal filler for tablets. When the dosage is more than 50%, the hydrophobicity of the drug can be improved.

Carboxymethyl starch sodium is a good disintegrating agent for tablets. It is a white or almost white powder, odorless, hygroscopic in the air, dispersing in water to become sticky