They are compact single screw dosers and are used generally to dose raw materials and additives in the plastics industry.

The products that can be processed with dosers G and GY have the shape of granules, pellet or lentils with dimensions that vary from 1mm until 6-7 mm. These products are constituted mainly by thermoplastic polymers. Their characteristic is to be very free flowing and easy to dose, given their characteristics.

The dosers G and GY are not suitable to dose powder products, flakes or fibers that can often present flowability issues. For this kind of product it is suggested to use powder dosers series CH, CHW, CHY, BH, BHW ,BHY, DFV, DFW and DFY or flakes and fibers dosers series VF, VFW and VFY.

These dosers can be volumetric (G) or gravimetric (GY).

In the gravimetric version (GY), the doser is hung to load cells with its hopper . The load cells are off-center or flexion type, made in aluminium or in stainless steel with protection grade up to IP67, available also with Atex certification when requested.

The dosers series G and GY are equipped with dosing screws quite similar to the ones used in dosers for powders. Given the good flowing of the products, these dosers do not need agitators inside. Therefore their dimensions are particularly small also for high flow rates.

The entire range of dosers G and GY is constituted by 13 standard sizes that allow to cover a capacity range from a minimum of 1 kg/h to a maximum of 5.000 kg/h.

The dosers G and GY have a compact design and construction. Their maintenance is simple and fast because they are constituted by triclamp fittings coupled together.

The dosing device G and GY is designed to house dosing screws with different dimensions and shape and also interchangeable with each other thanks to a suitable plastic adapter .

The transmission group that moves the dosing screw is constituted by a worm type gearbox and three-phase electric motor. In cases where a very wide throughput range is required (the range between the minimum and maximum dosage capacity is more than 1 to 10) brushless type motors are used, that allow very slow rotation speed so as to achieve very small capacities.

The shaft mechanical seals are made with shielded bearings and dust tight rings available in different materials such as NBR, SILICONE, PTFE EPDM and VITON.

Atex certified motors are available eventually equipped with a temperature probe and a anti-condensation heating devices when it is requested.

The dosing screws motor can be controlled by a frequency converter , and can be eventually servoventilated. The brushless type motors are controlled by their specific digital servo-drive. Using these controlling devices it is possible to regulate the rotation speed of the dosing screw in order to obtain the wanted capacity in a predefined minimum and maximum range. The real achievable capacity range depends also on the characteristics of the product to dose. Using asynchronous motors generally it can be covered a range from 1 to 8 between minimum and maximum. The adjustment range can increase until 1 to 30 using brushless motors.

Vertical T spouts complete the set of this kind of dosers. They are mounted at the end of the front outlet tube to vertically guide the product falling down while dosing.

It is possible to combine with the dosers a wide variety of standard loading hoppers with different capacity.

The loading hoppers have normally a truncated conical, symmetrical or skewed shape. They have easily removable lids and a round loading inlet for the automatic refilling. Above the loading hoppers it can be eventually installed storage hoppers with automatic discharging valves that are cyclically actioned to provide the doser refilling.

Both the loading hoppers and the storage hoppers can be equipped with wide transparent polycarbonate sight glasses.

The storage hoppers can be manually or automatically supplied. In this last case the use of vacuum loaders series ATS and AJS is frequent. They are installed directly on the hopper lids with flange coupling.

As accessories of the hoppers there are level sensors, to detect the presence of product and allow the automatic refilling cycles. The most used sensors are capacitive types, rotary level sensors, vibrating level switches to choose according to the product characteristics.

The most used construction materials are stainless Aisi 304 and 316L. For the plastic adapter of the dosing screw are used materials such as HDPE, PTFE and ACETAL.

The dosing screws can be simply pickled or also mirror-polished. It is possible to have the certifications of the contact materials on request.

The outer surfaces are satined 180 mesh. It is possible to have them also glass bead blasted, electro-polished or mirror-polished on request.

The gaskets are made in dust-tight rubber , such as SBR or NBR. They are available also with FDA certification on request.

The dosers G and GY and their loading hoppers can be completed by assembly structures properly dimensioned to house eventual storage hoppers with their vacuum loaders, in order to form an integrated and compact dosing group.

The construction materials used for the assembly structures are stainless steel Aisi 304 and painted carbon steel.

Sometimes the entire dosing group is installed on a mezzanine, placed over the production line and being integral part of an intermediate service floor, usually provided to house other machines for the line.

Both G dosers and gravimetric GY can be certified Atex 21/22 and Atex 21/21.

Electrical control panels can also be supplied including software specifically designed accordingly to the requested functionality.