Sometimes you are completely absorbed in your tasks. Everything is easy and seems to flow by itself – you are “in the flow“. Those who have ever dealt with the filling of powders can even better understand the metaphor behind this term. In order to make sure that the powder can be dosed at all, it must flow or be prepared to flow. Frequently, this is not an easy task, because as diverse as powders are, as different are their flow properties. Dosing systems have to be designed and adapted accordingly.
A suitable solution for many powders is the auger doser from Harro Höfliger. It provides precision, flexibility and is even capable of reliably advancing cohesive powders: Initially, it is located in a container, with the dosing unit – the eponymous auger – positioned in the center. Rotating movements convey the material to its destination, for example the reservoir of an inhaler.
Closing mechanism of the auger doser
In order to keep the powder moving, the hopper has a special stirrer for powder fluidization. Stirrer and auger have separate drives so that the powder can be better controlled during dosing stops. However, especially with very well flowing powders, such dosing stops are a real challenge for quite a few auger dosers; the powder may continue to trickle, causing contamination and inaccurate dosing results.
Closing sleeve lowered, discharge opening closed, no powder flow
Closing sleeve lifted, discharge opening open, powder flow is released
Therefore, for more than ten years, Harro Höfliger‘s system has included a special locking mechanism. The discharge opening of the dispensing cylinder is open during dosing and will close automatically when dosing stops. This is done by means of a sleeve which, when closed, rests on the closing cone of the dosing auger so that the powder cannot escape. That way, the powder is kept flowing when – and only when – it is desired.
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Photos: Helmar Lünig