Roller compaction advantages

An advantage of roller compaction is the increase in bulk density resulting in a reduced tablet size. It can also be used to improve the content uniformity of low-dosage compounds. Characteristics which afifect the tabletability of roller compacted formulas include over-lubrication and precompression of the compact. Typically, the powder is roller compacted between 15 and 40 kN of force prior to tablet compression. 

Compared to wet granulation and roller compaction, the direct compression platform allows tablet manufacture with fewer unit operations, as listed in Table 7.1. The sections that follow discuss several advantages and disadvantages of using direct compression for tablet manufacture. 

One big advantage of continuous processing arises from the demand for a precise and stable process control. Hereby, the IPC can be reduced and the surveillance of the process can be reduced. Therefore, continuous processes have a reduced need for control after reaching steady-state conditions (Fig. 18). Roller compaction described in another chapter of this book is also a good example of a continuous granulation technique. 

Therefore, it is likely that operating a briquetting roller press at the slowest possible speed consistent with economic throughput would be advantageous in reducing stress differences during compaction. Moreover, a slower roller speed will allow more time for any time-dependent recovery to attain equilibrium and plastic flow to reduce high stress concentrations. 

The advantages of using roller presses for such processes over tumble/growth agglomeration are that there are essentially no requirements on the fineness of the material to be agglomerated and that normally no binders are necessary. The compaction/... 

The continuous compaction between two rollers offers the advantages of large capacity and high apparent density. However, since an endless thin sheet is formed from elongated and often tortuous pieces, there is no hope of making individual compacts that can be easily charged into the remelting furnaces, similar to the cylindrical briquettes from the punch-and-die process. 

The advantage of vibrating rollers is that the desired compaction is achieved in less number of passes in contrast to all the other rollers. Furthermore, vibrating rollers can achieve better compaction or compact more effectively thicker layers (Nunn 1985 Tunnicliff 1977). 

The pneumatic-tyre roller is usually used at the intermediate and final phase of compaction. Using the pneumatic-tyre roller at the final compaction phase has the advantages of obtaining a better surface texture and eliminating hair cracks, which may be created when compacted with steel-wheel rollers. The latter is common when final compaction is carried out at a lower than appropriate temperature. 

In the hand lay-up technique the fibers are placed in a mold and the resin is later applied by rollers. One option is to cure using a vacuum bag. This removes the excess air and the atmospheric pressure exerts pressure to compact the part. The simplicity, low cost of tooling and flexibihty of design are the main advantages of this procedure. On the other hand, the long production time, intensive labor, and low automation potential are some of the disadvantages. 

---