As a consequence of a diverse range of properties, powders have proven to be highly functional materials, however they are notoriously difficult to handle. Powder behaviour is complex and cannot simply be categorised as universally “good” or “bad”. Powders can change their behaviour with a slight increase in ambient moisture, or if vibrated for a fraction of a second. Some have a tendency to stick to processing equipment, become electrostatically charged, change their characteristics if mixed at a different speed, or for an increased duration. These are complex materials, and if well understood their properties can be used to our advantage. However, if poorly characterised, a powder’s attributes can easily cause production problems and quality issues with the product.
The kinds of challenges confronted by industry vary enormously, but typical questions include: -
- Can I use this new grade of raw material in my existing formulation without introducing production or quality issues?
- What is the optimum water content required to ensure ideal final product attributes?
- Can blend uniformity be achieved using a slower mixing speed, perhaps for a longer mixing time?
- Will this powder flow out of my hopper in a consistent way?
- How can we enhance this formulation so that we can run the process faster and make more product, without compromising quality?
- Why is this batch giving us problems, when it should be performing as well as the last batch?
- Is this powder so cohesive we won’t be able to eliminate the agglomerates during mixing?
- Will this grade of raw material agglomerate and densify when passed through the screw feeder?
- Why are the tablets laminating after compression?
There are literally hundreds of questions routinely asked across formulation, development, production and quality departments, and solving these normally requires an understanding of the characteristics of the powder to quantify powder flow. Whilst the solution is not always easy to attain, having access to important properties of the material being processed is the starting point to understanding the problems and engineering a solution.