Batch feeding is typically used to manufacture blended products that involves feeding individual ingredients or materials based upon their weight percentage in a blend. Ingredients are categorized as majors, minors and micros, depending on their weight percentage. Two types of feeding are used for batch feeding: Gain-in-Weight and Loss-in-Weight feeding.
A Gain-in-Weight (GIW) batching system is usually used to batch major ingredients. This type of feeding station features volumetric feeding equipment, such as screw feeders, vibratory feeders, or valves that feed the material (based on motor output) to a hopper on load cells.
The Loss-in-Weight (LIW) batching system is usually used to batch micro and minor ingredients. This type of feeding features gravimetric feeding equipment, such as loss-in-weight screw or vibratory feeders, which are mounted on individual load cells or scales.
Volumetric feeders are often used in GIW applications for controlled batch feeding and dry bulk materials. In some applications, the material is batched directly into IBCs (Intermediate Bulk Containers), hoppers or drums. Other times, material is batched into industrial blenders.
GIW batching involves volumetric feeders dispensing multiple ingredients in sequence into a collection hopper mounted on load cells. In most cases, the volumetric feeder dispenses approximately 90% of the batch at high speed, slowing down towards the end of the batch to dispense the last 10% at a reduced rate. Our feeders feature a “dribble mode” in order to ensure higher accuracy.
A controller monitors the amount of each ingredient being fed, and signals each volumetric feeder to start, increase or reduce speed, or stop according to the target batch amount. When all of the materials have been fed in their appropriate amounts, the batch is successfully complete.
If individual ingredients must be weighed and fed more accurately, then a LIW batching system is used. Another criteria that requires a LIW batching system is when batch cycle times must be very short. In this form of batching, gravimetric feeders simultaneously feed multiple ingredients into a collection hopper. The LIW controller “controls” the amount of material being dispensed by sending a signal to the motor depending on the current feed rate that the controller reads.
Since each feeder has a set of load cells, this method of batching produces highly accurate batches for each ingredient. When all of the materials have been fed in their appropriate amounts, the batch is successfully complete. This method is very valuable if the application involves expensive materials that can be saved by carefully weighing and feeding through the LIW controller. This form of batching meters all of the ingredients into the collection hopper at the same time, eliminating the layering effect (as seen in GIW batching) and the time and cost for further processing.
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