Selecting the right components for your gain-in-weight batching system is crucial to achieving your desired batching accuracy. To begin, you’ll need the following information about your batch:
•Ingredient bulk density. This is the bulk density, expressed in pounds per cubic foot or kilogram per liter, of each ingredient in your batch.
•Ingredient batch weight. This is the quantity of an ingredient, expressed in pounds or kilograms, that must be added to the batch to meet the batch recipe requirement.
•Batch time. You need to know two times: batch dispense time, which is the time available in your process for the entire batch to be emptied from the batch container into the downstream process, and time between batches, which determines how much time is available for dispensing all ingredients for a batch into the batch container. Both times depend on your downstream process, such as how long your mixer takes to mix a previous batch and discharge it before the mixer is ready to accept a new batch.
•Desired batch accuracy per ingredient. This accuracy, typically expressed as pounds or kilograms within a certain tolerance (such as 10 pounds ±0.05 pounds), will help you make calculations for selecting and sizing the batching system components.
Most automated batching systems can handle many ingredients. To help you design a complex system that that handles multiple ingredients and achieves the batching accuracy you need, follow these tips:
•Calculate each ingredient feeder’s feedrate based on the feeder’s coarse and fine feedrates and times.
•Choose a batch container scale with a resolution several times more accurate than your desired batch accuracy for the ingredient with the smallest batch weight setpoint.
•Select a batch time for each ingredient that’s long enough (for best results, 30 seconds or longer) to ensure that the preact can stop the feeder at a point that leaves a very small percent of the batch weight in flight.
•Choose ingredient feeders with a repeatable feedrate; if the feeders are screw feeders, they should also have a reliable ingredient agitation mechanism.
•Make sure that the dust collection system uses minimal airflow, and don’t allow the dust capture hood to touch the batch container scale.
•Choose a batch container that will empty completely.