Screw feeders or spiral feeders can be either continuous feeders or batching units.
Continuous feeding is characterised by releasing a constant amount of product over a set time.
Over a set time, the batching unit must release a set quantity of product over a series of programmable cycles.
Depending on the type of product and the application, you can opt for a batching element with a flexible rotating spiral or a screw feeder with central shaft.
By varying the rotation speed of the spiral or screw feeder a corresponding variation of flow is obtained: the precision obtainable is therefore volumetric.
The speed control can be achieved manually, usually with gear motors controlled by inverters or, more rarely, by mechanical or hydrostatic variators.
Gravimetric feeders, similar to volumetric feeders, may also operate in a continuous or batch basis.
In this case, measuring is optimised with precision weighing. During weighing operations load cells are used to detect the variation in weight of the measured product.
In the control panel a weighing processor is inserted which, by means of the signals coming from the load cells, suitably manages the rotation speed of the spiral.
The speed control is generally obtained automatically by means of a geared motor driven by a frequency inverter. In this case, the accuracy depends on the type of cells used and on the ratio of the tare to the single weighing wanted.
Depending on requirements controllers can be set up to manage multiple components and recipes. Systems can be designed for Loss-in-Weight dosing or Gain-in-Weight systems.
An important accessory used with Gimat’s powder feeders are Flat bottom agitators also known as Flat bottom extractors, used below hoppers and tanks for the discharge of powder, milled and mixed substances.
These bin dischargers become necessary and are particularly advantageous in the presence of products that clog with low fluidity, or if the installation is in a confined space.
The Flat bottom agitator quickly unloads laterally by means of a special conical blade with a section with uniform resistance and blades protected from wear and tear.
The special design of the blade allows you to completely empty the contents of the hopper of the powder feeder leaving minimum residue, making it particularly popular in the food industry and generally in all applications in which the subject of cleaning is very important.
In addition to the powder feeders described above, Gimat also produces vibrating feeders, also known as vibrating feeding system.
These are particularly suitable for transporting and measuring loose granular products in bulk or fragile substances that can damage if carried with a spiral or screw conveyor.
Vibration is achieved by means of electromagnets.
They are widely used in the chemical, pharmaceutical, food, plastics and packaging industries placed inside the packaging machines.
Thanks to a special controller with vibrating feeders it is possible to adjust the flow rate and therefore the measuring of the components in a precise and reliable manner.
The vibrating base is the “engine” of this type of feeder and is selected according to the needs of the customer.