3 Important Points to Consider
For Packaging Powders
Free-Flow or Non-Free-Flow...
Are the particles of a powder product cohesive?
Free-flowing powder products are not cohesive such as table salt or granulated sugar. In theory these should 'flow freely' when dispensed. By adding extra pressure these types of powders will not usually compact or hold their shape when manipulated.
On the other hand, brown sugar or milk powder are non-free-flowing as the particles are cohesive. They hold their shape when manipulated and can be compacted when under pressure.
If you are looking to succeed in your powder packaging project (we are certain you are!), then careful consideration should be taken to determine whether your product is free-flowing or non-free-flowing. Once you have determined this, the best filling machine for your application can be specified which will ensure your product can be properly dispensed into its packaging.
Free-flowing products fall easily under gravity while on the other hand non-free-flowing products require more help to move due to their cohesive properties.
As a general rule of thumb, free-flowing powder products can be filled using volumetric or free-flow auger type filling machines. Non-free-flowing powder products require an auger filler specifically designed to dispense cohesive products.
The importance of Bulk Density
Much like determining between a free-flowing powder and a non-free-flowing powder, the bulk density of a powder product conveys both the 'flowability' of the powder and how much it can compact under pressure. One way of calculating the bulk density of a product is to divide the total volume from the total mass, giving a bulk density in a representative form of g/cm3.
As we discussed earlier, granulated sugar is a typical free-flowing powder product that will not compress much and has a low bulk density. Brown sugar is quite the opposite, a cohesive powder product which has a higher bulk density and will become harder when compacted.
So how does bulk density impact the specification of powder packaging equipment?
Consider packing 100g of compacted brown sugar vs 100g of dried herbs. Both products weigh the same but the package sizes will be considerably different due to the amount of empty space around and inside of the products. The brown sugar contains less empty space and is more compressed inside the package allowing for a smaller package to be used. Whereas the dried herbs contain much more empty space and do not compress much, requiring a much larger package.
This is how bulk density has a direct impact on the size and type of package or pouch required, the type of filler required, as well as flow rates and speeds that can be achieved.
Handling dusty products
We've all seen the affects of pouring a non-free-flow powder such as flour, dust just seems to get everywhere as well as creating a 'dust cloud'. Inevitably dust continues to appear on surfaces long after and far from where the product was originally poured out.
These dusty powder products can cause serious mechanical failures to powder packaging equipment if not fully considered and preventative measures taken to handle them. Therefore certain options on powder packaging equipment are recommended when a powder product is dusty:
- IP rating to be dust protected will prevent particles from getting into equipment enclosures.
- A dust extraction system will help to pull the dust away from the source, and is best positioned at the filling head.
- High speed continuous motion packaging maintains a constant downward airflow which helps to keep stray particles flowing directly into the package below.
Experts in powder packaging...
In conjunction with G Webb Automation, we Proquip Solutions consider powder packaging equipment one of our strongest areas of expertise. Having successfully installed and commissioned many powder packaging lines into sectors such as:
- Dairy powder
- Pharmaceutical / Nutraceutical
- Health & Nutritional