volumetric and gravimetric feeders

We produce feeders and micro feeders (single-screw and twin-screw) for precision dosing of powders and granules.

Gravimetric feeders (screw and spiral feeders) for batch and continuous dosing.

Dosage is achieved with accuracy by volume or weight.

In case of continuous volumetric feeding, there is no immediate monitoring of capacity, but this is based on the initial parameter settings, assuming that the hourly capacity is constant. The error inherent to a system of this kind is on the order of +/- 5%.

In case of continuous gravimetric feeding, there is constant monitoring of the hourly capacity set in the control software and using a closed-loop PID controller to adjust the speed of the doser depending on the output reported by the weighing system. The error inherent to a system of this kind is less than +/- 2% and also depends on the correct choice of the doser depending on the product to be measured.

Powder feeders design

In the weighing function, load cells are used to add or subtract weight depending on the function required and whether batch or continuous type.

The accuracy, in this case, also depends on the type of load cells used and the incidence of the tare on the individual weight desired.

The RPM and the flow rate can be adjusted by means of:

  • Three-phase induction motors driven by vector inverters and additional servo-ventilation, minimum flow rate equal to 1/10 of maximum flow rate.
  • Brushless motors with dedicated drives, for an even wider dosing range, with a minimum flow rate equal to 1/20 of the maximum flow rate.

The capacities and dosages obtainable with both volumetric and gravimetric feeders vary from a few grams per minute to hundreds of kilos per hour depending on the models chosen during the design stage, based on the customer’s requirements.

The feeder programmers used can manage several components and formulas, depending on the configuration. In case of multiple dosages or components, dedicated PLC software can be developed with recipe setting via HMI user friendly touch panels for integration in industry 4.0 system.

Upon request the screw feeders can be designed and built in conformity to ATEX 2014/34/EU Directive Zone 2 – 22 / Zone 1 – 21