Gain-in-Weight
Gain-in-weight (GIW) is a gravimetric feeding method in which a container's weight gain is measured during material feed.
What is gain-in-weight used for?
In contrast to the loss-in-weight method, not the material loss of a feeding system is measured, but rather the amount of material introduced into a weighing container.
Gain-in-weight is primarily used for batch feeding. In this processing method, one or more components are dispensed into a common container one after another, where they are combined into a defined batch.
How does gain-in-weight work?
In the gain-in-weight method, the receiving or weighing container rests on load cells. A feeder dispenses the material, while the weight gain is continuously recorded. Once the target weight has been reached, the material feed is stopped.
If several components are measured out, they can be introduced into the same weighing container one after another. The control system monitors the respective weight gain for each component. After completion of the feeding process, the finished batch can be conveyed to the downstream process.
To achieve the target weight as precisely as possible, the feed rate can be reduced towards the end of the feeding process. This combination of coarse and fine feeding allows for a high initial throughput followed by a more precise approach to the defined target weight.
Loss-in-weight or gain-in-weight?
Both methods are gravimetric, but they differ in their measurement principles and applications. In loss-in-weight feeding, the feeding system's decrease in weight is measured to determine and regulate a continuous mass flow. In contrast, the gain-in-weight method measures the weight gain of a receiving container to provide a defined quantity – or batch – of material.
Which method is suitable depends on whether a process requires a continuous material feed or the feeding of defined batches.