Chris Radley Danaher Motion Wood Dale, Ill.

In a typical sorting operation, packaged products stream or merge onto a common conveyor where they are identified (inducted) and gapped and then sorted into takeaway lines. Motion components making up each subsystem include motors, gears, belts, pulleys, bearings, controllers, and sensors.

Sorting is the act of merging, identifying, inducting, and separating products to be conveyed to specific destinations. This discussion focuses on the sorting of products packaged in containers, such as cartons, boxes, and plastic bags. The sorting of bulk materials is ignored because it's usually accomplished with little motion control.

Sorting systems typically consist of four subsystems. Each subsystem performs a specific operation: merge, induct, sort, and post-sort or takeaway. In the merge process, packaged products are moved from the picking area on an accumulation conveyor line and consolidated for presentation at the induct area.

The induct process involves determining the destination of each product (by inspection) and then creating the proper gap between them as they are released to the sorter. Common inspectionmethods include visual, automatic identification, bar code, weight, and machine vision.

In the sort process, products are diverted to the outbound post-sort or takeaway subsystem (sort lines). It would be easy to equate the entire sorting operation to just this step in the process, but without prior and subsequent steps, the sort step would be viewed simply as separation or diversion.

The final operation in a sorting system, post-sort or takeaway, moves the product to shipping, palletizing, staging, or on for additional sorting.

Sort it out

Merge and sort operations typically incorporate diverters, which require a fair amount of motion control. Diverters shift products from one path (or conveyor) to another. They have to be very fast in order to alter the path of selected products without disturbing others.

The challenge can be likened to switching trains from one track to another. Some trains are diverted to the side track, while others are permitted to pass through on the main track. In high-speed sorting machines, however, "trains" ( products) are comparatively close together and moving very fast. Diverters therefore must be equally fast, acting and then returning to the starting position, so that only the paths of selected products are altered.