Continuous gravimetric dosing of powdered products AZODOS® product family

4 Dec 2019  |
OSTERBURKEN - AZODOS® type P … DV dosing unit is used for volumetric metering of powdered products in weighing and finishing processes. The machine can be used in the food, pharmaceuticals, chemicals and plastics industries for feeding production processes with a constant mass flow in coarse or fine flow.

By adding a weighing device, the machine can be extended to form the AZODOS® type P… DW dosing system for gravimetric feeding of processes. The machine can be used as loss-in-weight scales to dose small quantities into the downstream system with gram accuracy.

Continuous gravimetric dosing of powdered products AZODOS® product family
AZODOS® P50/2 DV dosing unit

The AZODOS® P… DW is used with the AZO®CONT dosing controls for feeding continuous gravimetric processes, resulting in a DDW loss-in-weight feeder.

Key advantages

  • stainless chrome nickel steel design with various surface finishes
  • high grade dosing screws
  • easy-to-clean system for rapid changeover of components
  • compact design
  • easy to extend thanks to modular design
  • maximum dosing accuracy thanks to coarse/fine dribble feed
  • double screw version for bulk materials with poor flow properties
  • a range of screw geometries, adapted to product properties


  • used as loss-in-weight feeder
  • precise online adjustment control and quick correction in case of any deviations from target values
  • absolute weight registration
  • no falsification due to bulk density fluctuations
  • no intricate calibration work
  • measurement value logging with high resolution

Design of AZODOS® types P … DV and DW

The basic machine consists of a housing where, depending on the model, one or two dosing screws are installed. The dosing screws are driven by frequency-controlled gear motors. An upstream discharge agitator serves to ensure that the dosing screws are evenly filled from surge bins. The surge bins are available in a variety of models and sizes and, depending on the model, can be filled under gravity, pneumatically or manually. An extraction device can be used to remove the dosing screws from the back of the housing, which makes cleaning or replacing individual components very simple.

If the basic machine is expanded with a platform load cell or a 3-point weighing frame, this forms an AZODOS® type P … DW dosing system that can be used as loss-in-weight scales. Flexible connections at the supply hopper inlet and screw outlet decouple the system thus preventing force shunts. If the AZODOS P….DW is combined with the AZO®CONT dosing controls, this creates a loss-in-weight feeder. The controls continuously regulate the mass flow in terms of target and actual throughput.

Operating principle of AZODOS® type P … DV, DW, DDW

The AZODOS® Type P … DV operates in volumetric mode. The powder bulk products flow out of the supply hopper into the dosing screw. An agitator is used to ensure uniform discharge. With a frequency-controlled motor, the dosing screw can be switched from coarse to fine flow for precision dosing in the downstream weighing process.

In the case of dosing scales, the basic machine is mounted on a platform load cell or integrated in a 3-point weighing frame. It can be mounted in a frame structure on the floor or suspended from the ceiling. The dosing screw meters the bulk material in coarse/fine flow to the downstream process. The amount of product that is metered out of the AZODOS® is weighed. The system operates gravimetrically in accordance with the negative weighing principle.

AZODOS® P70/1 DW dosing unit with 3-point weighing unit
AZODOS® P70/1 DW dosing unit with 3-point weighing unit

The AZODOS® type P … DW becomes a loss-in-weight feeder if an appropriate control system (e.g. AZO®CONT) is provided. The bulk material is discharged by the dosing screw and the resulting loss in weight per unit of time is registered by the weighing and control system. The actual loss in weight per unit of time (actual throughput) is compared against the required setpoint, which is defined by the downstream process, e.g. extruder. Differences between the actual decrease in weight and the decrease in target weight over time are corrected by adjustments to the batch controller’s throughput.

Once the product reaches a predefined level in the AZODOS®, the control process is paused briefly and the surge bin is refilled. During the refill time the dosing screw output is set to a value based on empirical weight and output data gained from previous dosing cycles.

Operation and control

Up to 10 dosing stations can be controlled with the central AZO®CONT controller. The system is displayed and its parameters set on an operator control panel. A PC-based visualisation system (Intouch, WinCC, etc.) can be connected corresponding to requirements. An interface for the KASTOR process control system is additionally integrated in the controller. Extensive work flows such as balancing and recipe handling can be implemented with this process control system. The material feed for replenishing the dosing units can be additionally controlled with the AZO®CONT controller. AZO®CONT can control up to four independent collective feeding system with max. 32 receivers.

The most diverse requirements can now be configured with a single AZO®CONT control unit. This is regardless of whether this involves controlling up to 10 AZODOS® dosing units or whether up to an additional four collective feeding systems are to be controlled with a maximum of 32 receivers in total.

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AZO provides innovative bulk material handling, raw material handling, pneumatic conveying systems,mixer feeding, screeners & bulk containers for the reliable automation of production processes for the industry in foodstuff, pharmaceutical, chemical and plastic. We plan,...

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