- Binders hold the ingredients of a formulation together in a tablet. Binders ensure that tablets, powders, granules, and others can be formed with the required mechanical strength. Moreover, they give volume to low-active dose tablets.
- The term “Binding” describes when the tablet sticks/takes hold of the die or splits during the molding/pressing process.
- During the process, a film is built on the molding or die area, restraining the ejection of the tablet. If there is excessive binding, the sides of the tablet might become cracked and can crumble.
- Tablet manufacturing involves a series of processes all aimed at the result of a uniform fine piece of art tablet. This article aims at exploring the causes and remedies of binding in tablet manufacturing. The processes include sizing, milling, drying, and compressing among several other procedures. Well, in each of the processes, there are possibilities of defects that give rise to associated problems.
- For tablet compression, which is aimed at delivering tablets with designated hardness, the associated problem is binding. In other words, it could be regarded as binding to the die. Once the tablet binds to the die, it does not eject properly, resulting in a deformed tablet.
- The primary causes of the binding problem relate to lubricant and pressure on the die side and moisture on the end of the tablet. Expounding on the binding defect, it could be said that the tablet tends to bind to the die if the die is not sufficiently lubricated.
- On the other hand, too much moisture resulting from insufficient drying may cause binding regardless of proper die lubrication.
- Diving deeper into the lubrication cause of binding, inappropriate or little lubrication is bound to cause binding. The solution for binding related to lubrication is the use of the right type of lubricant or increasing the amount of lubricant in situations in which the lubricant is less.
- Binding usually occurs when there is little to no lubrication, too much moisture in the granules used, or when worn out or old dies are being used. Binding issues caused by the granulation process are summarized below, alongside potential solutions to these problems.
Problem | Solution |
Moist granules. Moisture can be seen around the lower punch. | Increase drying time of granules |
Noisy ejection (occasional cracking tablets) | Increase the quantity of lubricant used |
Overly Coarse Granules | Reduce granular size by adjusting mesh size on granulation machinery |
Excessively hard granules. Too hard for the lubricant to be effective | Reduce the mesh size of the granule. If using a wet granulation process, reduce drying time. |
Granular material abrasive and damaging tooling | Reduce the size and density of granules. If not possible then use higher-density tooling |
Granular material sticks to die | If too warm reduce the temperature. Increase clearance if it is extruding |
Problem | Solution |
Bad quality tooling | Polish to improve the finish or purchase new tooling |
Rough die surfaces due to abrasion | Replace tooling with higher-quality tooling |
Undersized dies. Too little clearance | Machine down dies to increase clearance |
Too much pressure | Reduce pressure or modify granulation |
