Question: What conditions lead to a Divert Abort occurring on a Sliding Shoe Sorter?

What are the reasons for aborted cartons on sliding shoe sorters?

Why do items abort on sorters

Environment:

Sliding Shoe Sorter
BOSS 3 Control System
InControlWare Control System
MC4 Control System

Answer:

For the purposes of this article, the BOSS/ICW/MC4 system will be referenced as the Control System. Most Intelligrated systems have the same or very similar item abort logic.

In general, an item is Aborted when the system determines that product would not be able to successfully divert to a given lane, after the product has already entered sortation and after the product has already been given a lane assignment.  This is a protective measure for the sorter, so that an after-sort lane does not receive more product than it is physically capable of handling.  Should product be unable to fully fit in an after-sort lane and be stopped while still partially on the sorter, it could lead to damage of the product and/or damage to critical sortation components.

Divert Aborts are known to occur in at least two scenarios:

1) The intended after-sort lane has a full condition or is otherwise unable to receive product (Disabled, etc.).  Since the Control System is treating the lane as unable to receive product, any items already in sortation with that lane as a destination will be Aborted so as not to end up on a lane that cannot accept further product.

2) The control system determines that the rate of diverting items for a given location is too high in a period of time, and limits that rate by aborting items. With respect to the sorter status, the destination will not be labeled 'full', so this scenario is typically invisible to operators. The system maintains a threshold of total product inches assigned to a destination, and once that threshold is exceeded, items are aborted until the rate declines to below the limit again. This rate is different for each sorter and may even be different on different destinations within the same sorter. It can be roughly estimated by looking at the difference between the speed of the sorter vs. the speed of the after-sort destination line/s.

To prevent item aborts, it is important to clear product from after-sort lanes such that they do not trigger full conditions.  If product entering the sorter from a particular location (merge lane) is consistently destined for the same sorter lane/location, aborts of that product could be mitigated by controlling releases to the sorter from the location in question.