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Rev. May 2001 GraviMaster-FGB-M05 (S) Page 3
Gravimetric Blender
1.0 INTRODUCTION
GRAVIMETRIC FEEDING
An effi cient materials blending system is an essential feature of the modern plastics
processing industry. Dosing each component on the basis of weight shows distinct
advanta ges over traditional volumetric systems. The quantity of material delivered is
precise and unaffected by variations in bulk density, fl ow characteristics and particle size.
Ferlin Plastics Automation now have a range of more than twenty blenders that deliver
the benefi ts of gravimetric blending at a price that makes other gravimetric ... and most
volumetric systems ... look distinctly expensive.
FGB SERIES GRAVIMETRIC BLENDERS
“GraviMaster” blending systems are available in more than twenty diffe rent models with a
throughput capacity range from 10 to 750 kg/hr for the standard units. The number of
components on the standard unit is two to six. But purpose-built units may designed for
additional feeds up to a maximum of ten and a throughput capacity up to 1500 kg/hr.
The blending units may either fl ow-control-valve design or have a combination with
auger-feeders. The proven “GraviMaster” blending systems are being used successfully in
Injection-moulding, Blow-moulding, Sheet-extrusion and Film-extrusi on.
ACCURATE WEIGH SYSTEM
Each component is dispensed into a weigh-pan using one set of load cells. When all the
components are correctly weighed, the blend is discharged into a mixing chamber. A high
effi ciency horizontal mixer is programmed to give a uniform blend which discharges to a
storage bin with suction device, or directly into the processing machine hopper.
The system is capable of extremely accurate measurements of additive, even at very small
percentages or ratios. Load cells of the highest accuracy are used, weighing to within
0.01 gm. The accuracy of the process is enhanced by the software system which is
designed to compensate in a subsequent batch for any errors arising in a prece ding batch.
Overall accuracy of 0.1% can be achieved.
COMPACT AND MODULAR CONSTRUCTION
The units are designed and built as a modular construction using standard components
where possible, so that all components are readily obtainable. All components which
are in contact with the raw material are made in stainless steel. This includes hoppers,
valves, augers, weigh pan, mixer and mixing chamber. When auger feeders are instal led,
these can be quickly accessed for easy cleaning. The mixing chamber and weigh pan can
be removed easily for cleaning and access. The construction is in accordance with the
essential require ments under the CE regulations.