Broadly defined, accumulation is the collecting or gathering of packages, product, totes, etc, in preparation for the next step in processing.
Accumulation, in general, performs several vital functions in a material handling system:
• It can act as buffer, or temporary storage area, regulating the flow of packages moving toward downstream processes.
• It can regulate the frequency and quantity with which packages are released. For instance, before a conveyor merge or induction to hold groups of packages until it is their turn to enter.
• It can also be used for any role which requires the product to slow down or stop.
• Accumulation is essential in high speed production lines to ensure generating units continue to run during the malfunction or downtime of downstream equipment.
• And due to the inherent real-world unpredictability of what items are needed and when, the accumulation of items while waiting for other operations to receive them is a necessity to any material handling system.
When operating in an accumulative mode, an ECC’s firmware is reliant on input from photo eyes, the PLC, and operations downstream to determine when to start and stop motor driven rollers. A photo eye that is located within a zone is said to be the local photo eye of that zone, or ‘local to the zone’.
And every zone operating in an accumulative mode should have a local photo eye feeding input to the zone’s ECC. Photo eyes communicate whether a zone is empty, or occupied. And keep in mind, if a zone is set to operate in an accumulation mode, but the zone has no local photo eye, it will be logically relegated to operating in transportation mode.